IS 15884 : 2010

IS 15884 : 2010

and substantially continuous enclosure made wholly In addition, where a real-time clock is fitted, the
of insulating material, including the terminal cover, battery shall be capable of providing reserve power
which envelopes all metal parts, with the exception for the minimum operation life of the meter, on the
of small parts, for example, nameplate, screws, basis of an initial 2 years of continuous reserve use.
suspensions and rivets. If such small parts are Thereafter, the RTC battery shall be capable of
accessible by the standard test finger (as specified providing reserve power for one week per year for a
in IS 1401) from outside the case, then they shall be minimum of 8 further years.
additionally isolated from live parts by supplementary
insulation against failure of basic insulation or The meter shall display current account information
loosening of live parts. The insulating properties of in terms of balance amount left for consumption in
lacquer, enamel, ordinary paper, cotton, oxide film on terms of energy units or monetary value.
metal parts, adhesive film and sealing compound, or Where multiple values are presented by a single
similar unsure materials, shall not be regarded as display, all relevant values shall be available via
sufficient for supplementary insulation. appropriate selection (choice of selection shall be
For the terminal block and terminal cover of such a general, for example keypad or push button). When
meter, reinforced insulation is sufficient. displaying the values, each tariff register shall be
identifiable and the active tariff rate shall be
4.2.8 Resistance to Heat and Fire — The terminal indicated. (This can be done either by legends or by
block, the terminal cover, the insulating material display headers before the actual parameter.)
retaining the main contacts in position and the meter
NOTE — For testing purpose; a means of reading the
case shall ensure reasonable safety against the energy register to within 0.01 kWh resolutions shall be
spread of fire. They should not be ignited by thermic provided. This may be via the display or by other means
overload of live parts in contact with them. The (for example. Meter reading instrument). For monetary
displays the resolution shall be one rupee. For tariff rates
material of the terminal block should not deflect under
the resolution shall be 1 paisa.
heating. To comply therewith they must fulfil the
tests as specified in 5.2.4 of this standard. The register shall be able to record and display
starting from zero, for a minimum of 1 500 h, the
4.2.9 Protection Against Penetration of Dust and energy corresponding to maximum current at
Water — The meter shall conform to the degree of reference voltage and unity power factor. The register
protection IP51 as per IS 12063, but without suction shall not roll over during this duration.
in the meter.
NOTES
If a token carrier acceptor is fitted to the meter, then
1 Values higher than 1 500 h should be the subject of purchase
the tests shall be carried out without any token carrier
contract.
in place in the token carrier acceptor.
2 It shall be impossible to reset the indication of the
Immediately after the tests and without disturbing cumulative total of electrical energy during use. The regular
roll over of the display is not considered as a reset.
the meter, the payment meter shall operate correctly
and a valid token shall be accepted on the first or 4.2.10.3 Minimum character size — The height of
subsequent presentation, up to a maximum of 4 the display characters for the principal parameters
attempts. values shall not be less than 5 mm.
For testing, see 5.2.5. 4.2.10.4 Minimum displa y ca pa bility — The
following information shall be capable of being
4.2.10 Display of Measured Values
displayed on the prepayment meter:
4.2.10.1 General
Cumulative kWh energy registers (energy
The display shall be visible from the front of the consumption)
meter. The display shall be electronic and when the
Available credit value
meter is not energized, the electronic display need
not be visible. The principal unit for the measured In addition for virtual token systems, the prepayment
values shall be the kilowatt hour (kWh). meter shall be able to display details of the last
purchase transaction token.
4.2.10.2 Retention time of the non-volatile memory
4.2.10.5 Additiona l displa y r equir ements for
For long outages, the payment meter shall be
prepayment meter operating in monetary units —
designed such that any data necessary for correct
The prepayment meters where the available credit
operation shall be retained for a minimum period of
register operates in monetary units, the following
10 years without an electrical supply being applied
information shall be capable of being displayed:
to the meter.

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IS 15884 : 2010

a) The price per kWh, and The distance of the optical pulse output from further
b) Any time-based charge settings such as for adjacent ones or from an optical status display shall
standing charges or debt recovery. be sufficiently long that the transmission is not
affected. An optimum pulse transmission is achieved
In the case of a multi-rate prepayment meter, the when, under test conditions, the receiving head is
following additional information shall also be capable aligned with its optical axis on the optical pulse output.
of being displayed:
The rise time (tT) given in Fig. 4 in Annex F shall be
a) The price per kWh for each tariff rate, and verified by a reference receiver diode with rise time
b) Cumulative kWh for each tariff rate. (tT) < 20 μs.

For multi-rate tariff the active tariff rate shall be 4.2.10.9 Optical characteristics — The wavelength
indicated. of the radiated signals for emitting systems shall be
between 550 nm and 1 000 nm.
Where a multi-rate prepayment meter is operated from
an internal real time clock, the time shall also be The output device in the meter shall generate a signal
capable of being displayed. with a radiation strength ET over a defined reference
surface (optically active area) at a distance of a 1 =
4.2.10.6 Display indicators — The following shall 10 + 1 mm from the surface of the meter, with the
be indicated as a minimum and shall be visible from following limiting values:
the front of the prepayment meter (in the form of
parameter selection on display): a) ON-condition: 50 μW/cm2 < ET < 1 000 μW/
cm2, and
a) Indication of rate of kWh consumption
b) OFF-condition: ET < 2 μW/cm2 (see also
(instantaneous loading), and
Fig. 5 in Annex F).
b) Indication of token acceptance (for all manually
transported token types). 4.2.11 Marking of Meter

4.2.10.7 Output device — The meter shall have a 4.2.11.1 Nameplates

test output device accessible from front and capable
Every meter shall bear the following information as
of being monitored with suitable testing equipment.
applicable:
The operation indicator, if fitted, shall be visible from
the front. a) Manufacturer’s name and/or trade-mark and
the place of manufacture;
Output devices generally may not produce
homogeneous pulse sequences. Therefore, the b) Designation of type;
manufacturer shall state the necessary number of c) The number of phases and the number of wires
pulses to ensure that measurement uncertainty factor for which the meter is suitable (for example
due to repeatability of meter is less than 1/10 of the single-phase 2-wire, three-phase 4-wire); these
error limits specified at different test points and markings may be replaced by the graphical
consistent with desired resolution. symbols given in IS 12032 series;
The resolution of test output in the form of pulses or d) The number and year of manufacture. If the
high resolution register, whether accessible on the serial number is marked on a plate fixed to the
meter through external display, shall be sufficient to cover, the number shall also be marked on the
conduct satisfactorily accuracy test at lowest test meter base;
point defined in particular requirements in less than e) The reference voltage in one of the following
5 min and starting current test in less than 10 min. forms:
1) The number of elements if more than one,
4.2.10.8 Mechanical and electrical characteristics —
and the voltage at the meter terminals of
An optical test output shall be accessible from the front.
the voltage circuit(s); and
The maximum pulse frequency shall not exceed 2.5 kHz. 2) The rated voltage of the system or
secondary voltage of the instrument to
Modulated and unmodulated output pulses are
which the meter is intended to be
permitted. The unmodulated output pulses shall have
connected.
the shape shown in Fig. 4 in Annex F.
Examples of voltage markings are shown in
The pulse transition time (rise time or fall time) is the
Table 4.
time of transition from one state to the other state,
including transient effects. The transition time shall f) Principal unit in which the meter reads, for
not exceed 20 μs (see Fig. 4 in Annex F). example kWh;

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 IS 15884 : 2010

Table 4 Voltage Marking

(Clause 4.2.11.1)

Sl M et er Volta ge at t h e Ter m in a ls of th e Rated System Voltage

No. Volt a ge C ir cu it (s) V
V
(1) (2) (3) (4)

i) Single-phase 2-wire 230 V 230 230

ii) Three-phase 4-wire 3-element 3 × 230 (400) 3 × 230/400
(230 V phase to neutral)

g) Basic current and the maximum current, for The prepayment electricity meter shall have a
example, 10-60A or 10(60) A for a meter having mechanism for transferring tokens. The token may
a basic current of 10A and a maximum current be entered by keypad or smart cards. The credit
of 60A; transfer device shall be intrinsically safe and provide
h) Reference frequency in Hz; protection from damage by means of dust, water,
sharp objects and electrostatic discharges.
j) Meter constant, for example in the form: Wh/
imp or imp/kWh; 4.2.12.3 Keypad interface
k) Class index of the meter;
Where a keypad interface is fitted, it shall be designed
m) Reference temperature if different from 27°C; to operate for a minimum of 20 000 operations of each
n) Sign of the double square for insulating individual key.
encased meters of protective Class II;
4.3 Climatic Requir ements
p) Battery symbol, if the meter has an inbuilt
battery and its chemical symbol (for example, 4.3.0 General
Li, if Lithium);
The tests shall be carried out with the payment meter
q) Ratings of any auxiliary switch shall be marked in the prepayment mode, and with the load switch
on the nameplate in case the system uses an closed, unless otherwise stated.
auxiliary switch;
r) Meter can also be marked with the BIS Where a token carrier acceptor is fitted, then the tests
Standard Mark (if certified by BIS); and shall be carried out without any token carrier
acceptor during these tests.
s) Country of manufacture.
4.3.1 Oper ation Within the Specified Opera ting
Information under (a), (b), (c) and (p) may be marked
Range
on an external plate permanently attached to the meter
cover. This is the range of ambient temperature (that is from
–10 to +55°C) forming part of the payment meter’s
NOTE — Information under (m) to be mutually agreed
between the manufacturer and the customer.
rated operating conditions for metrological and
functional purposes, with limits of variation in meter
4.2.12 Token Carrier Interface error with ambient temperature specified in terms of
maximum limits for the mean temperature coefficient.
4.2.12.1 General
Within this temperature range, the operation of the
Where a physical token carrier interface is fitted, it power supply circuits, the display and any push
shall comply with the following mechanical buttons, the meter accounting process and any
requirements. associated registers and parameters, the load
switches, the token interface and/or any local or
4.2.12.2 Token carrier acceptor remote communications interface, plus any multi-rate
Where a token carrier is fitted, an insertion force facility and any auxiliary input and output circuits
required to insert a token carrier into the token carrier shall all be correct; a valid token shall be accepted,
acceptor shall not exceed 10N. The force required to and an invalid token shall be rejected or ignored
remove a token carrier from the token carrier shall without damage or cancellation.
not exceed 10N. The meter shall be designed such Where an internal real-time clock is fitted for internal
that under normal circumstances, and with a properly tariff control or time-based credit release, then
maintained token carrier, the minimum number of reference to Annex D shall be made. Within this
insertions for which a token carrier acceptor shall temperature range and when there is no supply
operate is 10 000. voltage applied to the payment meter, the status of

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IS 15884 : 2010

all registers, values, and parameters associated with functional characteristics of the meter when
the meter accounting process shall continue to be the supply voltage is subsequently restored.
valid and free from corruption and there shall be no Where an internal real-time clock is fitted for
changes to the metrological and functional internal tariff control or time-based credit
characteristics of the meter when the supply voltage release then reference to Annex D shall be
is subsequently restored. made. Correct operation of all aspects of the
payment meter shall resume when the supply
4.3.2 Operation Within the Limit Range of Operation voltage has returned to within the extended
a) Outside the specified operating range but operating range. However, where the meter is
within the limit range of operation (that is from fitted with a real-time clock for tariff purposes
–25 to +60°C) and when the supply voltage and this no-supply-voltage condition persists
applied to the payment meter is within the for a time period longer than the operational
extended operating range (see 4.4.2.1 and reserve, then it is permissible that the time may
4.4.2.3), the following operational need to be reset.
requirements shall apply: c) Storage and transport outside the limit range
The status of all registers, values, and of operation — Outside the limit range of
parameters associated with the meter operation, but within the limit range for storage
accounting process shall continue to be valid and transport (that is from –25 to +70°C) and
and free of corruption. Where an internal real- without any supply voltage applied to the
time clock is fitted for internal tariff control or payment meter, the following requirements
time-based credit release, then reference to shall apply:
Annex D shall be made. No discrepancies The status of all registers, values, and
between the cumulative kWh register(s) and parameters associated with the meter
available credit value shall become evident as accounting process shall continue to be valid
a result of any such ambient temperature and free from corruption and there shall be no
excursions outside the specified operating range. resulting damage or degradation to the
metrological and functional characteristics of
A valid token need not be accepted when
the meter. Under these conditions the
presented, but the information on the token
operation and time-keeping accuracy of any
carrier shall then not be altered or invalidated.
time-keeping facility with an operation reserve
However, when a valid token is accepted, the
that is incorporated in the payment meter are
credit amount shall be transferred correctly to
not specified. When the ambient temperature
the meter and the credit information of the
of the payment meter has returned to the
token itself shall have been invalidated. An specified operating range and stabilized and
invalid token shall not be accepted, altered or after the supply voltage has been connected
damaged by presentation to the meter. and then commissioning (including the
The display need not operate, or is permitted resetting of any time-keeping facility) has
to operate erratically. The state of the load been completed, the meter shall operate
switch shall not alter without appropriate normally.
conditions prevailing in the meter accounting 4.3.3 Temperature Range
process, and any otherwise permissible
restoration to the on state shall not occur The temperature range of the meter shall be shown
without additional manual intervention. in Table 5. For testing, see 5.3.

Correct operation of all aspects of the payment Table 5 Temperature Range

meter shall resume when the ambient Indoor Meter Range
temperature has returned to within the °C
specified operating range. (1) (2)
Specified operating range –10 to 55
b) Outside the specified operating range, but Limit range of operation –25 to 60
within the limit range of operation, and when Limit range for storage and –25 to 70
transport
there is no supply voltage applied to the
payment meter the status of all registers, NOTES
1 For special application, other temperature values can be
values, and parameters associated with the used according to purchase contract.
meter accounting process shall continue to be 2 Storage and transport of the meter should only be at the
valid and free from corruption and there shall extremes of this temperature range for a maximum period of
be no changes to the metrological and 6 h.

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 IS 15884 : 2010

4.3.4 Relative Humidity 4.4.1.2 Current circuits

The meter shall be deemed to meet the relative humidity The apparent power taken by each current circuit of
requirements of Table 6. For combined temperature and a direct-connected payment meter at maximum
humidity testing (see 5.3.3). current, reference frequency, and reference
Table 6 Relative Humidity temperature shall not exceed a value in VA equivalent
to 0 08 percent of Vref in volts multiplied by 100
Annual mean <75 percent percent of IMax in amperes (for example 230 V and
For 30 days, these days being spread <95 percent 60 A gives 11 VA; 230 V and 100 A gives 18.4 VA).
in a natural manner over one year
Occasionally on other days <85 percent The internal heating test shall also be met.

The limits of relative humidity as a function of These values include consideration of the load switch.
ambient air temperature are shown in Annex C. 4.4.2 Influence of Supply Voltage
4.4 Electr ical Requir ements 4.4.2.1 Voltage range
Where relevant, and unless otherwise specified, the Payment meters shall comply with the requirements
tests shall be carried out with the payment meter in of Table 7.
the prepayment mode.
Table 7 Voltage Ranges
The load switch shall be in the closed position for
each of these tests, unless otherwise specified. Specified operating range 0.9 to 1.1 Vref
Limit range of operation 0.0 to 1.2 Vref
Where a token carrier acceptor is fitted to the Extended operating range 0.7 to 1.2 Vref
payment meter, then the tests shall be carried out Withstand range 0.0 to 1.9 Vref
without a token carrier in place in the token carrier
acceptor, unless otherwise specified. For verification of voltage range, see a lso 4.6
and 5.6 (including any sub-clauses).
Where these requirements permit a temporary
degradation of performance or loss of function during 4.4.2.2 Specified operating range
the tests then within a maximum period of 15s after
the end of the tests the payment meter shall operate This is the range of supply voltage forming part of
correctly in accordance with the relevant the payment meter’s rated operating conditions for
requirements without and external intervention. No metrological purposes, with specified limits of
change of actual operating state or stored data is variation in percentage error with supply voltage.
allowed. No change of actual operating state or stored 4.4.2.3 Extended operating range
data is allowed. See 6.2 for checks at the beginning
and end of tests. Where an internal real-time clock is This is the range of supply voltage over which the
fitted for internal tariff control or time-based credit payment meter shall operate correctly. Within this
release then reference to Annex D is also to be made. range, the operation of the power supply circuits,
the display and any push buttons, the meter
4.4.1 Power Consumption accounting process and any associated registers,
The measurement of power consumption in the values, parameters, and timekeeping, the load
voltage and current circuits shall be determined as switches, the token carrier interface and/or any local
given in this clause. or remote communications interface, plus any multi-
rate facility and any auxiliary input and output circuits
4.4.1.1 Voltage circuits shall all be correct; a valid token shall be accepted,
and an invalid token shall be rejected without damage
The active and apparent power consumptions in each
or cancellation. Outside the specified operating range
phase of a direct-connected prepayment meter at
of supply voltage, but within the extended operating
reference voltage, reference temperature, and
range, the limits of variation in percentage error of
reference frequency shall not exceed 3 W and 10 VA,
the meter are three times the values applicable within
including the auxiliary power supply consumption.
the specified operating range.
Short-term increases in consumption due to the
4.4.2.4 Limit range of operation
reading/writing of a token or the operation of a
switch are permitted. Where the meter is fitted with a Outside the extended operating range of supply
token acceptor and the token can be retained in the voltage but within the limit range of operation and
payment meter then these power consumption when the ambient temperature is within the specified
requirements shall also be met with a normal token operating range the following operational
retained in the meter in quiescent operation. requirements shall apply:
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IS 15884 : 2010

The status of all registers, values, and parameters apply to single-phase three-wire payment meters,
associated with the meter accounting process shall where the maximum withstand voltage shall first be
continue to be valid and free of corruption. The error applied to test the first line voltage and current, and
of the meter may vary between +10 and –100 percent then repeated to test the second line voltage and
and no discrepancies between the cumulative kWh current – in each case without any supply voltage
register(s) and available credit value shall become applied to the unused line terminal. No load current
evident as a result of any such supply voltage flows through to the neutral terminal in any of these
excursions outside the extended operating range. testing arrangements.
A valid token need not be accepted when presented, For three-phase four-wire polyphase types, the
but the information on the token carrier shall then payment meter shall withstand, without a safety
not be altered or invalidated. However, when a valid hazard arising, the maximum withstand voltage (1.9
token is accepted the credit amount shall be Verf) applied to any two phases and neutral with a
transferred correctly to the meter and the credit phase angle of 60° between the two phase voltages.
information of the token itself shall have been The maximum withstand voltage shall be applied for
invalidated. An invalid token shall not be accepted, a period of 4 h together with a current of 50 percent
altered or damaged by presentation to the meter. of IMax and unity power factor in each of the two
phases under test. A total of three test runs is
The display need not operate, or is permitted to required to cover the pairs of phases, with a cooling
operate erratically. The state of the load switch shall period of 1 h between each run. This supply voltage
not alter without appropriate conditions prevailing withstand requirement does not apply to three-phase
in the meter accounting process, and any otherwise three-wire direct-connected payment meters.
permissible restoration to the ‘on’ state shall not
occur without additional manual intervention. For all polyphase types, the payment meter shall
continue to operate with any combination of one or
Correct operation of all aspects of the payment meter more phases remaining connected and supplying
shall resume when the supply voltage has returned power when the supply voltage is within the
to within the extended operating range. However, extended operating range. In the case of a three-
where the meter is fitted with a real-time clock for phase, three-wire network (where the meter is
tariff purposes and the supply voltage is below designed for this service), this requirement shall be
0.8 Vref for a time period longer than the operational met when any two of the three phases remain
reserve, then it is permissible that the time may need connected. Any internal timekeeping facility shall
to be reset. continue to maintain timekeeping under these
NOTE — Where requirements for a meter function that conditions, without having to run on any operational
specifically opens the load switch during low or high supply reserve fitted.
voltage conditions are agreed between purchaser and
supplier of the payment meter, it shall be possible for this 4.4.2.7 Voltage dips and short interruptions
function to be inhibited when assessing compliance with
this clause, without changing any relevant firmware. Voltage dips and short interruptions shall not
4.4.2.5 Withstand range produce a change register of more than X units and
the test output shall not produce a signal equivalent
Outside the limit range of operation, but within the of more than X units. The value X is derived from the
supply voltage withstand range, the payment meter following formula:
may sustain permanent damage and degradation to
its metrological and functional characteristics, but X = 10-6.m.Vref.IMax
this shall not give rise to a safety hazard (for example where
exposure of live conductors, fire, explosion, or m = number of measuring element;
undesirable restoration of the supply).
Vref = reference voltage, in volts; and
4.4.2.6 Abnormal voltage conditions IMax = maximum current, in amperes.
For single-phase types, the payment meter shall Where the payment meter is fitted with a token carrier
withstand, without a safety hazard arising, the acceptor and the token carrier can be retained in the
maximum withstand voltage (1.9 Vref) applied between meter then these tests shall be carried out with and
the line voltage and neutral terminals. The maximum without a customer token carrier inserted in the meter
withstand voltage shall be applied for a period of 4 h during the tests. Where the token carrier cannot be
together with a current of 50 percent of IMax and unity so retained these tests shall be performed without
power factor (in the case of two-element single-phase any token carrier in place in the token carrier acceptor
two wire meters 50 percent of IMax in each measuring during the test. No tokens shall be presented to the
element simultaneously). This requirement shall also meter for action during these tests.

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 IS 15884 : 2010

Voltage dips and short interruptions shall not 4.4.4 Influence of Self-Heating
produce any loss or corruption of data in the payment
meter, whether a token carrier is inserted in the meter The variation of error due to self-heating shall not
or not. Data on the token carrier shall not be exceed the values given in Table 9.
corrupted when the latter is inserted and retained in Table 9 Variations Due to Self-Heating
the meter for the duration of these tests. (Clauses 4.4.4 and 5.6.5)
After the tests, a valid credit token shall be presented. Sl Va lu e of P ower Limits of Var iation in
The token and payment meter shall then operate No. C u r r en t Factor Per centage Er r or for Meter s
correctly, including operation of the load switch off of Class
and on. 1.0 2.0
(1) (2) (3) (4) (5)
The test shall be carried out first with the load switch
i) IMax 1 0.7 1.0
closed and it shall be in or resume the closed position
ii) IMax 0.5 1.0 1.5
at the end of the test. The test shall be repeated with
inductive
the switch open and it shall remain open throughout
the test. The test shall be carried out as follows: after the
voltage circuits have been energized at reference
4.4.3 Influence of Short-Time Overcurrents voltage for at least 2 h for Class 1 and 1 h for Class 2,
Short-time overcurrent shall not damage the meter without any current in the current circuits, the
and the switch shall remain operative. The meter shall maximum current shall be applied to the current
perform correctly when back to its initial working circuits. The meter error shall be measured at unity
conditions and the variation of error shall not exceed power factor immediately after the current is applied
the values shown in Table 8. For testing (see 5.4.3). and then at intervals short enough to allow a correct
drawing to be made of the curve of error variation as
The meter shall be able to carry a short-time over- a function of time. The test shall be carried out for at
current of 30 IMax for one half-cycle at rated frequency. least 1 h, and in any event until the variation of error
during 20 min does not exceed 0.2 percent.
The load switch may open under the test conditions,
but it should be possible to close it by simple manual The same test shall then be carried out at 0.5
operation on the meter by the user. (inductive) power factor. The cable to be used for
Table 8 Variations Due to Short-Time Overcurrent energizing the meter shall have a length of 1 m and a
(Clauses 4.4.3 and 5.4.4) cross-section to ensure that the current density is
between 3.2 A/mm2 and 4 A/mm2.
Sl Va lu e of P ower Limits of Var iation in
No. C u r r en t Factor Per centage Er r or for Meter s 4.4.5 Influence of Heating
of Class
Under rated operating conditions, electrical circuits
1.0 2.0 and insulation shall not reach a temperature, which
(1) (2) (3) (4) (5)
might adversely affect the operation of the meter.
i) Ib 1 1.5 1.5
The temperature rise at any point of the external
Short-time overcurrents shall not damage the load surface of the meter shall not exceed 20 K with the
switch. The switch shall still operate under specified ambient temperature at 45°C.
conditions, the surroundings of the payment meter The cable used for energizing the payment meter
shall not be endangered and protection against shall be insulated copper and have a minimum length
indirect contact shall be assured in all cases. of 1 m and a cross section to ensure that the current
Testing shall be carried out with the meter energized density is less than 4 A/mm2.
and with the load switch closed and the switch 4.4.6 Insula tion
contacts shall remain closed after the test
overcurrent has been applied. The meter and its incorporated auxiliary devices
including any tokens carrier that may be inserted
The open-circuit source voltage of the generator into the token carrier acceptor shall be designed such
used to provide the current waveform for this test that they retain adequate dielectric qualities under
shall be Vref ± 5 percent. The period of time for which normal conditions of use. Where a token carrier
the generator voltage is maintained at the terminals acceptor is fitted the meter shall withstand both the
after the overcurrent has occurred shall be one impulse voltage test and the ac voltage test with a
minute. For polyphase payment meters and load metallic token in the token acceptor or, if the token
switches, the test may be performed on a phase-by- carrier cannot be retained, a suitable electrical
phase basis. connection to the token carrier interfaces. Such

15
IS 15884 : 2010

metallic tokens or electrical connections shall then 4.5.3 Radio Interference Suppression
be connected to the ground reference for the
purposes of these tests. After these tests, and when The meter shall not generate conducted or radiated
the payment meter has been restored to reference noise, which could interfere with other equipment.
conditions, the payment meter shall operate For testing (see 5.5.5).
correctly. 4.6 Accur acy Requir ements
4.5 Electr omagnetic Compatibility (EMC) 4.6.1 Limits of Error Due to Variation of the Current
4.5.1 General Test Conditions The requirements given in 5.6.1 shall apply, without
Any time-based charging shall be set to zero for the a token inserted in any token acceptor fitted to the
duration of these tests. The initial available credit payment meter. If a token acceptor is fitted and a
and any settings in the payment meter shall be such token can be retained in the payment meter then
that the load switch is not expected to operate during additional accuracy tests shall be carried out under
these tests. The load switch shall not operate during reference conditions at Vref and unity power factor,
these tests, but for other functions a temporary with balanced loads, and at both 0.05 Ib and IMax. The
degradation or loss of function or performance is limits of variation in percentage error compared to
acceptable unless stated otherwise. the same load point and no token present in the token
acceptor shall then be 0.3 for meters of Class 1, and
4.5.2 Immunity to Electromagnetic Disturbance 0. 5 for meters of Class 2. The payment meter shall be
mounted as for normal service.
The meter shall be designed in such a way that
conducted or radiated electromagnetic disturbance When the meter is under the reference conditions
as well as do not damage or substantially influence given in 5.6.1, the percentage errors shall not exceed
the meter. For testing, see 5.5. the limits for the relevant accuracy class given in
NOTE — The disturbances to be considered are: Tables 10 and 11.
a) electrostatic discharges, The difference between the percentage error when
b) electromagnetic HF fields, the meter is carrying a single-phase load and a
c) fast transient burst, and balanced poly phase load at basic current and unity
d) surge immunity test. power factor shall not exceed 1.5 percent and 2.5

Table 10 Percentage Er ror Limits

(Single-Phase Meters and Polyphase Meters with Balanced Loads)
(Clauses 4.6.1 and 5.6.6)
Sl Value of Cur r ent Power Factor Per centage Er r or Limits for M eter s of Class
No.

1.0 2.0
(1) (2) (3) (4) (5)
i) 0.05 Ib < I < 0.1 Ib 1 ±1.5 ±2.5
ii) 0.1 Ib < I < IMax 1 ±1.0 ±2.0
iii) 0.1 Ib < I < 0.2 Ib 0.5 inductive ±1.5 ±2.5
0.8 capacitive ±1.5 —
iv) 0.2 Ib < I < IMax 0.5 inductive ±1.0 ±2.0
v) When specially requested 0.25 inductive ±1.0 —
by the user: from 0.2 Ib < 0.8 capacitive ±3.5 —
I < IMax ±2.5 —

Table 11 Percentage Er ror Limits (Polyphase Meter s Car r ying a Single-Phase

Load, but with Balanced Polyphase Voltages Applied to Voltage Circuits)
(Clauses 4.6.1, 5.6.6 and D-3.1 and Table 12)
Sl Value of Cur rent Power Factor Per centage Er r or Limits for M eter s of Class
No.

1.0 2.0
(1) (2) (3) (4) (5)
i) 0.1 Ib < I < IMax 1 ±2.0 ±3.0
ii) 0.2 Ib < I < IMax 0.5 inductive ±2.0 ±3.0

16
 IS 15884 : 2010

percent for meters of Classes 1 and 2 respectively. The additional percentage error due to the change of
influence quantities with respect to reference
NOTE — When testing for compliance with Table 10, the
test current shall be applied to each element in sequence. conditions, as given in 5.6.1 shall not exceed the limits
for the relevant accuracy class given in Table 12.
4.6.2 Limits of Error Due to Other Influence Quantities

Table 12 Influence Quantities

(Clauses 4.6.2, 5.5.3, 5.5.4 and 5.6.2.4)
Sl Influence Quantity Va lu e of C u r r en t Power Factor L im it of Va r ia t ion in
No. (Ba la n ced Un less Per centage Er r or for
O t h er wise Sp ecified ) M et er of C la ss
1.0 2.0
(1) (2) (3) (4) (5) (6)
i) Voltage variation ±10 % (see Note 1) Ib 1 0.7 1.0
0.5 inductive 1.0 1.5

ii) Frequency variation ±5 % Ib 1 0.5 0.8

0.5 inductive 0.7 1.0

iii) Wave form; 10 % of 3rd harmonic in current Ib 1 0.6 0.8

(see Note 2)

iv) Reverse phase sequence 0.1 Ib 1 1.5 1.5

v) Voltage unbalance (see Note 3) Ib 1 1.5 1.5

vi) Continuous magnetic induction of external Ib 1 2.0 3.0

origin 67 mT (see Note 4)

vii) Continuous abnormal magnetic induction Ib 1 4.0 4.0

of external origin 0.2 T (see Note 4)

viii) Magnetic induction of external origin 0.5 mT Ib 1 2.0 3.0

(see Note 4)

ix) Abnormal ac Magnetic induction of external Ib 1 2.0 3.0

origin (10 mT) (see Note 4)

x) Electromagnetic HF fields (see Note 5) Ib 1 2.0 3.0

xi) Fast-Transients burst test (see Note 5) Ib 1 4.0 6.0

xii) Operation of accessories (see Note 6) 0.05 Ib 1 0.5 1.0

xiii) dc and even harmonies in the ac current 0.5 IMax 1 3.0 6.0
circuit (see Note 7)

NOTES
1 For the voltage ranges from –30 percent to –10 percent and +10 percent to +20 percent the limits of variation in percentage
errors are three times the values given in Table 11.
Below 0.7 Vref the error of the meter may vary between +10 % and –100 %.
2 The distortion factor of the voltage shall be less than 1 %. The variation in percentage error shall be measured under two
conditions. The peak of third harmonic in first measurement in phase and in second measurement in anti-phase of the peaks
of the fundamental current. For polyphase meter, the voltage circuit shall be energized in parallel and current in series.
3 Polyphase meters with three measuring elements shall measure and register, within the limits of variation in percentage error
shown in this table, if the following one or two phases of the 3-phase network are interrupted, provided the reference phase
is available that is Y-phase for 3-phase 3-wire meters and neutral for 3-phase 4-wire meters. However the operation of the
meter shall not be affected by such removal of reference phase.
4 The test conditions are specified in 5.6.2.1 to 5.6.2.4.
5 Test conditions are specified in 5.5.3 and 5.5.4.
6 Such an accessory, when enclosed in the meter case, is energized intermittently, for example, the electromagnet of a multi-
rate register.
7 Test condition is specified in Annex K.

17
IS 15884 : 2010

4.6.3 Limits of Error due to Ambient Temperature homogeneous pulse sequences. Therefore, the
Va r ia tion manufacturer shall state the necessary number of
pulses to ensure a measuring accuracy of at least
The mean temperature coefficient shall not exceed 1/10 th of the accuracy limits of the meter at different
the limits given in Table 13. test points.
The determination of the mean temperature 4.6.6 Requirement of Time Keeping
coefficient for a given temperature shall be made over
a 20 K temperature range, 10 K above and 10 K below 4.6.6.1 Crystal controlled clock
that temperature, but in no case shall the temperature
be outside the specified operating temperature range. Where fitted a crystal-controlled time clock shall have
timekeeping accuracy better than 0.5 s/day at
Table 13 Temper ature Coefficient reference temperature. The variation of time-keeping
(Clause 4.6.3) accuracy with temperature shall be less than 0.15 s/
Sl Value of Power Mean Temper atur e °C/24 h. Test requirements and the influences of
No. Cu r r en t Factor C oefficien t P er cen t / supply voltage, frequency, and harmonics on
K for Meter s of Class timekeeping are under consideration.
4.6.6.2 Load switching capability
1.0 2.0

(1) (2) (3) (4) (5) 4.6.6.2.1 Performance requirements for load switching
utilization category UC1
i) 0.1 Ib to IMax 1 0.05 0.10
ii) 0.2 Ib to IMax 0.5 inductive 0.07 0.15 The load switch shall be designed and rated to make
and break at Vref, IMax with a linear resistive load and
4.6.4 Starting and Running with No-Load at Vref, I b , 0.4 inductive power factor for 3 000
operations.
For these tests, the conditions and the values of the
influence quantities shall be as stated in 5.6.1 except For the purposes of the requirements and tests given
for any changes specified below. in this clause, the load switch shall be considered as
an integral part of the payment meter and each test
4.6.4.1 Initial start-up of the meter shall be performed on the payment meter as a
Metering shall be functional within 5 s after the rated complete unit.
voltage is applied to the meter terminals. Unless otherwise specified, the supply input
4.6.4.2 Running with no-load terminals and the load output terminals of the
payment meter shall be taken to be the effective
When the voltage is applied with no current flowing terminals of the load switch.
in the current circuit, the test output of the meter
shall not produce more than one pulse. For testing In the case of a polyphase payment meter, the tests
(see 5.6.3). and test values given shall apply to each phase.

4.6.4.3 Starting The temperature rise for the load switch under high
current values is not specifically tested, but the
The meter shall start and continue to register at the complete meter shall pass the heating test given
current shown in Table 14. in 4.4.5.
Table 14 Star ting Cur rent There is no specific test for this requirement, but
precautionary measures shall be taken to protect the
Sl Power Factor C la ss of M et er
No.
load switch from adverse effects resulting from the
ingress of vermin into the payment meter.
1.0 2.0
(1) (2) (3) (4) There is no specific test for this requirement, but the
reading process of a valid token shall not be
i) 1.0 0.004 Ib 0.005 Ib
adversely affected by coincident switching of the
load switch while making or breaking currents under
4.6.5 Meter Constant rated operating values of voltage and current. If the
The relation between the test output and the token is not accepted due to the disturbance caused
indication in the display shall comply with the by the load switch, then it shall not be invalidated
marking on the nameplate. and shall be accepted when presented to the
payment meter subsequent to the disappearance of
Output devices generally may not produce the disturbance.

18
 IS 15884 : 2010

Once the load is interrupted by low credit in the meter Applicable to payment meters rated at maximum
accounting process, the load switch shall only be currents up to 100 A. There are no other particular
operable to restore the load after a further appropriate performance requirements for load switching apart
manual intervention, for example by pressing a from the short-time overcurrent withstand requirements
pushbutton or by manually presenting a further in 4.4.3. There is no requirement for the load switch
credit token. In the case of virtual-token-carrier- to also switch the neutral circuit.
operated meters, the acceptance of sufficient credit NOTE — Where the payment meter load switching
token value while in the interrupted state shall result capability is also used as part of the main circuit protection
in a change of load switch state to “enabled”. The or isolation at the customer’s premises then such additional
requirements may be specified through reference to other
load switch shall then be operable to restore the load
specifications or standards.
after appropriate manual intervention, for example
by pressing a pushbutton. 5 TESTS AND TEST CONDITIONS
4.6.6.2.2 Performance requirements for load switching 5.1 Gener al Testing Procedur es
utilization categories UC2 and UC3
5.1.1 Test Conditions
Where a payment meter has additional load switching
performance capabilities that meet the requirements All tests are carried out under reference conditions
for load switching utilization category UC2 or UC3 unless otherwise stated in the relevant clause.
such a payment meter shall comply with the relevant 5.1.2 Classification of Tests
requirements of Annex G.
The schedule and recommended sequence shall be
4.6.6.3 Specified rating as given in Table 20 in Annex E. In case of
These ratings do not apply to the load switch as a modifications to the meter made after the type test
component, but shall apply to the payment meter as and affecting only part of the meter, it will be
a complete unit, thus as applied between the supply sufficient to perform limited seats on the
input and load output terminals of the payment meter. characteristics that may be affected by the
modification.
The load switch shall remain correctly operable by
the payment meter for all values of supply voltage 5.1.3 Number of Sa mples a nd Cr iter ia for
present at the input terminals within the extended Conformity
operating voltage range of the payment meter. Type tests shall be applied to three test specimens;
The payment meter shall be able to make, carry and in the event of one specimens failing to comply in
break all values of currents between the minimum any respect, further three specimens shall be taken
switched current rating to the rated breaking current care of all of which shall comply with the requirements
for all values of the rated operating voltage range of the standard.
and the specified operating temperature range of the 5.1.4 Schedule of Acceptance Test
payment meter.
Required tests are marked with A in Table 20 in Annex E.
The rated breaking current (Ic) shall be equal to IMax
of the payment meter. 5.1.5 Recommended Sampling Plan and Criteria
for Acceptance
The minimum switched current shall be equal to the
nominal starting current of the payment meter. A recommended sampling plan and the criteria for
acceptance of the lot are given in Annex H of
The rated breaking voltage (Vc) shall be equal to the IS 13779.
upper limit of the extended operating voltage range
of the payment meter. 5.1.6 Schedule of Routine Tests

4.6.6.4 Performance requirements for load switching Required tests are marked with R in Table 20 in
Annex E.
The payment meter shall be capable of making and
breaking currents for 3 000 contiguous make-and- 5.1.7 Type Test
break operations at (Vc, Ic) with a linear resistive load,
All tests are carried out under reference conditions
together with 3 000 contiguous make-and-break
unless otherwise stated in the relevant clause.
operations at (Vc, 10A), with power factor 0.4 inductive.
The type test defined in Table 20 in Annex E shall be
Note that 1 operation is 1 make and 1 break, and the
made on three specimens of the meter, selected by
total of 6 000 make-and-break operations must be
the manufacturer, to establish its specific
met using a single specimen.
characteristics and to prove its conformity with

19
IS 15884 : 2010

the requirements of this standard. c) Pulse shape : Half sine wave

A recommended test sequence is given in Table 20 in d) Duration of the pulse : 18 ms
Annex E. e) Number of shocks : Two in both
directions of
In the case of modifications to the meter made after three mutual
the type test and affecting only part of the meter, it perpendicular
will be sufficient to perform limited tests on the axes (total of 12
characteristics that may be affected by the shocks)
modifications.
After conclusion of test, the meter shall show no
A detailed testing plan will need to be drawn up for damage or change in information and the variation
the specific type of payment meter to be tested. The of meter error shall not exceed 50 percent of accuracy
testing plan should take into consideration the class index at basic current , 5 percent basic current
following guidelines: and maximum current at Cos ij = 1 and shall satisfy
Several identical specimens of the meter are likely to the limits of error. Immediately after this test a valid
be required, the actual number being dependent upon token shall be accepted.
the interfaces and functionality of the specific 5.2.3 Vibration Test
payment meter, the testing facilities and time
constraints available, and the extent of any further The meter shall be subjected by the method specified
specific type-testing that may also be applicable in IS 9000 (Part 8) to vibration as detailed below:
under Annexes D or G of this part of this standard.
a) Meter in non-operative condition, without the
NOTES packing;
1 For some tests, it may be appropriate to test two b) Frequency range : 10 to 150 Hz;
specimens in parallel, with one to check accounting
consistency and the other to check the operation of the c) Transition frequency : 60 Hz,
load switch (such as for testing of climatic requirements).
[f< 60 Hz, constant amplitude of movement:
2 Where a specimen is subjected to any of the tests in 5.5
0.15 mm (0.3 mm p-p)
and its sub-clauses, then the matching requirements of D-5.1
may also be applicable. f > 60 Hz, constant acceleration: 2 × 9.8 m/s2.
(2 g)];
5.2 Tests of Mechanical Requirements
d) Single point control; and
5.2.1 Spring Hammer Test e) Number of sweep cycles per axis: 10.
The mechanical strength of the meter case shall be NOTE — 10 sweep cycles = 75 min.
tested with a spring hammer (see 12.3.3 of IS 13779 ).
The test shall be conducted on a different specimen
The meter shall be mounted in its normal working for each direction of vibration.
position and the spring hammer shall act on the
outer surfaces of the meter cover (including After conclusion of test, the meter shall show no
windows) and on the terminal cover with a kinetic damage or change in information and the variation
energy of 0.22 ± 0.05 Nm. of meter error shall not exceed 50 percent of accuracy
class index at basic current , 5 percent basic current
The result of this test is satisfactory if the meter
and maximum current at Cos = 1 and shall satisfy
case and terminal cover do not sustain damage which
the limits of error. Immediately after this test a valid
could affect the function of the meter and it is not
token shall be accepted.
possible to touch live parts. Slight damage which
does not impair the protection against indirect 5.2.4 Test of Resistance to Heat and Fire
contact or the penetration of solid objects, dust and
water is acceptable. The test shall be carried out according to IS 11000
(Part 2 / Sec1), with the following temperatures:
5.2.2 Shock Test
a) Terminal block and insulating material
The meter shall be subjected to shock test by method retaining the main contacts of the load switch:
specified in section 1 of IS 9000 (Part 7/Sec 1) to 960 ± 15°C;
shocks as described below: b) Terminal cover and meter case: 650 ± 10°C;
a) Meter in non-operating condition, without the and
packing c) Duration of application: 30 ± 1 s.
b) Peak acceleration : 400 m/s2 (40 g) The contact with the glow wire may occur at any

20
 IS 15884 : 2010

random location. If the terminal block is integral with a) Meter in non-operating condition;
the meter base, it is sufficient to carry out the test b) Temperature: + 70 ± 2°C; and
only on the terminal block.
c) Duration of the test: 72 h.
5.2.5 Tests of Protection Against Penetration of
5.3.2 Cold Test
Dust and Water
The test shall be carried out according to IS 9000
The tests shall be carried out according to IS 12063
(Part 2/Sec 1 to 4), under the following conditions:
under the following conditions:
a) Meter in non-operating condition;
a) Protection against penetration of dust b) Temperature: – 25 ± 3°C; and
1) Meter in non-operating condition and c) Duration of the test: 72 h.
mounted on an artificial wall;
5.3.3 Damp Heat Cyclic Test
2) The test should be conducted with sample
lengths of cable (exposed ends sealed) a) The test shall be carried out according to
of the types specified by the manufacturer IS 9000 (Part 5/Sec 1 and 2), under the
in place; following conditions:
3) If a token carrier acceptor is fitted to the 1) Voltage and auxiliary circuits energized
meter, then the tests shall be carried out with reference voltage;
without any token carrier in place in the 2) Without any current in the current
token carrier acceptor; circuits;
4) The same atmospheric pressure is 3) Variant 1:
maintained inside the meter as outside
4) Upper temperature: +40 ± 2°C for indoor
(neither under - nor over-pressure); and
meters;
5) First characteristic digit: 5 (IP5X).
5) No special precautions to be taken
Any ingress of dust shall be only in a quantity regarding the removal of surface moisture;
not impairing the operation of the meter and and
its token acceptor and its dielectric strength 6) Duration of the test: 6 cycles.
(insulating strength).
b) 24 h after the end of this test the meter shall
For testing, see 5.4.6.4 be submitted to the following tests:
b) Protection against penetration of water 1) Insulation tests according to 5.4.6, except
that the impulse voltage shall be multiplied
1) Meter in non-operating condition; and
by a factor of 0.8;
2) Second characteristic digit: 1 (IPX1).
2) A functional test. The meter shall show
Any ingress of dust shall be only in a quantity not no damage or change of information and
impairing the operation of the meter and its token shall operate correctly. Valid tokens should
acceptor and its dielectric strength (insulating accept normally.
strength).
c) The damp heat test also serves as a corrosion
For testing, see 5.4.6.4 test. The result is judged visually. No trace of
corrosion likely to affect the functional
Immediately after the IP51 tests without disturbing properties of the meter shall be apparent.
the meter, the prepayment meter shall operate
correctly and a valid token shall be accepted on the 5.4 Tests of Electr ical Requir ements
first or subsequent presentations up to a maximum
5.4.1 Test of Power Consumption
of four attempts.
The power consumption in the voltage and current
5.3 Tests of Climatic Influences
circuit shall be determined at reference values of the
After each of the climatic tests, the meter shall show influence quantities given in 5.6.1 by any suitable
no damage or change of the information and shall method. The overall accuracy shall be better than 5
operate correctly. After each of these tests, valid percent.
token shall be accepted by the meter.
5.4.1.1 Test of power consumption of voltage circuit
5.3.1 Dry Heat Test
For requirements, see 4.4.1.1.
The test shall be carried out according to IS 9000
5.4.1.2 Test of power consumption of current circuit
(Part 3/ Sec 1 to 5), under the following conditions:

21
IS 15884 : 2010

For requirements, see 4.4.1.2. voltage for at least 2 h for class 1, without any current
in the current circuits, the maximum current shall be
5.4.2 Tests of Influence of Supply Voltage applied to the current circuits. The meter error shall
5.4.2.1 Test of volta ge r a nge be measured at unity power factor immediately after
the current is applied and then at intervals short
For requirements, see 4.4.2.1. enough to allow a correct drawing to be made of the
5.4.2.2 Tests of the effect of voltage dips and short curve of error variation as a function of time. The
interruptions test shall be carried out for at least 1 h, and in any
event until the variation of error during 20 min does
a) The test shall be carried out under the not exceed 0.2 percent.
following conditions:
The same test shall then be carried out at 0.5
1) Voltage and auxiliary circuits energized (Inductive) power factor.
with reference voltage; and
2) Without any current in the current circuits The variation of error, measured as specified, shall
not exceed the value given in Table 8 (see also 4.4.4).
b) Voltage interruptions of Vref = 100 percent
5.4.5 Test of Influence of Heating
Interruption time: 1 s;
Number of interruptions: 3; and With each current of the meter carrying maximum
Restoring time between interruptions: 50 ms current and with each voltage circuit (and with those
(see also Fig. 6 in Annex H). auxiliary voltage circuits which are energized for
periods of longer duration than their thermal time
c) Voltage interruptions of Vref = 100 percent constants) carrying 1, 15 times the reference voltage,
Interruption time: 20 ms; number of the temperature rise of the external surface shall not
interruptions: 1 (see also Fig. 7 in Annex H). exceed 20 K, with an ambient temperature of 45°C.
d) Voltage interruptions of Vref = 50 percent During the test, the duration of which shall be 2 h,
Dip time: 1 min; and the meter shall not be exposed to draught or direct
solar radiation.
Number of dips: 1 (see also Fig. 8 in Annex H).
After the test, the meter shall show no damage and shall
e) Voltage dips and short interruptions shall not
comply with the dielectric strength test of 5.4.6.4.
produce a change register of more than x kWh
and the test output shall not produce a signal 5.4.6 Tests of Insulation Properties
equivalent of more than x kWh. The value x is
derived from the following formula: 5.4.6.1 General test conditions

x = 10 -6.m.Vref.IMax The meter and its incorporated auxiliary devices

including any tokens that may be inserted into the
where
token acceptor shall be designed such that they
m = number of measuring element; retain adequate dielectric qualities under normal
Vref = reference voltage in volts; and conditions of use. Where a token acceptor is fitted
I Max = maximum current in amperes. the meter shall withstand both the impulse voltage
test and the ac voltage test with a metallic token in
f) There shall be no change in the currency the token acceptor or, if the token cannot be retained,
registers. a suitable electrical connection to the token interface.
Such metallic tokens or electrical connections shall
5.4.3 Test of Influence of Short-Time Overcurrent
then be connected to the ground reference for the
The test circuit shall be practically non-inductive. purposes of these tests. After these tests, and when
the payment meter has been restored to reference
After the application of the short-time overcurrent conditions, the payment meter shall operate
with the voltage maintained at the terminals, the meter correctly.
shall be allowed to return to the initial temperature
with the voltage circuit(s) energized (about 1 h). The tests shall be carried out only on a complete
meter, with its cover (except when indicated hereafter)
For requirements, see 4.4.3. and terminal cover, the terminal screws being
5.4.4 Test of Influence of Self-Heating screwed down to the maximum applicable conductor
fitted in the terminals. Test procedure in accordance
The test shall be carried out as follows: After the with IS 2071 (Part 1).
voltage circuits have been energized at reference

22
 IS 15884 : 2010

The impulse voltage tests shall be carried out first 5.4.6.2 Impulse voltage test
and the ac voltage tests afterwards.
The impulse of 6 kV is applied. For waveform and the
During type tests, the dielectric strength tests are generator characteristics, see 12.7.6.2 of IS 13779.
considered to be valid only for the terminal
arrangement of the meter, which has undergone the For each test, the impulse voltage is applied ten times
tests. When the terminal arrangements differ, all the with one polarity and then repeated with the other
dielectric strength tests shall be carried out for each polarity. The minimum time between impulses shall
arrangement. be 3 s.

For the purpose of these tests, the term earth has the a) Impulse voltage tests for circuits and between
following meaning: the cir cuits — The test shall be made
independently on each circuit (or assembly of
a) When the meter case is made of metal, the circuits) which is insulated from the other
‘earth’ is the case itself, placed on a flat circuits of the meter in normal use. The
conducting surface. terminals of the circuits, which are not
b) When the meter case or only a part of it is subjected to impulse voltage, shall be
made of insulating material, the “earth” is a connected to earth.
conductive foil wrapped around the meter and Thus, when the voltage and the current circuits
connected to the flat conducting surface on of a measuring element are connected together
which the meter base is placed. Where the in normal use the test shall be made on the
terminal cover makes it possible, the whole. The other end of the voltage circuit
conductive foil shall approach the terminals shall be connected to earth and the impulse
and the holes for the conductors within a voltage shall be applied between the terminal
distance of not more than 2 cm. of the current circuit and earth. When several
c) In case of meters with apertures for token voltage circuits of a meter have a common
acceptors, a metal token inserted into the token point, this point shall be connected to earth
acceptor shall be construed as earth. and the impulse voltage successively applied
between each of the free ends of the
During the impulse and the a.c. voltage tests, the
connections (or the current circuit connected
circuits, which are not under test, are connected to
to it) and earth.
the earth as indicated hereafter. No flashover,
disruptive discharge or puncture shall occur. When the voltage and the current circuits of
the same measuring element are separated and
After these tests, there shall be no change at
appropriately insulated in normal use (for
reference conditions in the percentage error of the
example each circuit connected to a measuring
meter greater than the uncertainty of measurements.
transformer), the test shall be made separately
In this clause, the expression all the terminals means on each circuit.
the whole set of terminals of the current circuits,
During the test of a current circuit, the terminals
voltage circuits and, if any, auxiliary circuits having
of the other circuits shall be connected to earth
a reference voltage over 40 V.
and the impulse voltage shall be applied
These tests shall be made in normal conditions of between one of the terminals of the current
use. During the test, the quality of the insulation circuit and earth. During the test of a voltage
shall not be impaired by dust or abnormal humidity. circuit, the terminals of the other circuits and
one of the terminals of the voltage circuit
Unless otherwise specified, the normal conditions under test shall be connected to earth and the
for insulation tests are: impulse voltage shall be applied between the
a) Ambient temperature: 15-25°C; other terminal of the voltage circuit and earth.
b) Relative humidity: 45-75°; and The auxiliary circuits intended to be connected
c) Atmospheric pressure: 86 kPa-106 kPa. either directly to the mains or to the same
voltage transformers as the meter circuits, and
The requirement of the impulse voltage test shall with a reference voltage over 40 V, shall be
also be met (see 5.4.6.2). For the purpose of these subjected to the impulse voltage test in the
requirements, metallic objects of the same size and same conditions as those already given for
shape as the token carrier are inserted into the token voltage circuits. The other auxiliary circuits
carrier acceptor. This metallic token shall be shall not be tested.
considered to represent an auxiliary circuit with a
reference voltage below or equal to 40 V.

23
IS 15884 : 2010

b) Impulse volta ge test of electr ic cir cuits insulation tester to have come practically to rest.
relative to earth — All the terminals of the
electric circuits of the meter, including those 5.5 Tests for Electromagnetic Compatibility (EMC)
of the auxiliary circuits with a reference voltage 5.5.1 General Test Conditions
over 40V, shall be connected together.
For all these tests the meter shall be in its normal
The auxiliary circuits with a reference voltage working position with the cover and terminal covers
below or equal to 40 V shall be connected to in place. All parts intended to be earthed shall be
earth. In case of prepayment electricity meter earthed.
with token acceptor a metallic part need to
connect to earth shall be inserted into the After the application of EMC testing the payment
aperture. The impulse voltage shall be applied meter shall revert to normal function and performance
between all the electric circuits and earth. within a period of 1 min, without any external
intervention. After these tests, the meter shall show
5.4.6.3 ac voltage test no damage and operate correctly
The ac voltage test shall be carried out in accordance 5.5.2 Test of Immunity to Electrostatic Discharges
with Table 15.
a) The test shall be carried out first with the load
The test voltage shall be substantially sinusoidal, switch closed and repeated with the load
having a frequency between 45 Hz and 55 Hz, and switch open, and the load switch shall not
applied for 1 min. The power source shall be capable operate during the tests. Where the payment
of supplying at least 500 VA. meter is fitted with a token interface the tests
During the test no flashover, disruptive discharge, shall include air discharges to the keypad or
puncture shall occur. to a customer token inserted into the token
acceptor where such a token can be retained
During the tests relative to earth, the auxiliary circuits in the meter.
with reference voltage equal to or below 40 V shall
be connected to earth. In case of prepayment meter b) The test shall be carried out according to
with token acceptor a metallic part need to connect IS 14700 (Part 4/Sec 2) under the following
to earth shall be inserted into the aperture. conditions:

5.4.6.4 Insulation resistance test 1) Contact discharge;

2) Test voltage: 8 kV;
The insulation resistance test shall be carried out in
3) Test severity level: 4; and
accordance with Table 16.The voltage shall be applied
for a minimum of 1 min or more for the pointer of the 4) Number of discharges: 10.

Table 15 ac Voltage Tests

(Clause 5.4.6.3)
Sl Test Voltage Points of Application of the Test Voltage
No. (r ms)
(1) (2) (3)
i) 2 kV Tests to be carried out with the case closed, the cover and terminal covers in place
a) Between, on the one hand, all the current and voltage circuits as well as the auxiliary circuits
whose reference voltage is over 40 V, connected together, and, on the other hand, earth; and
b) Between circuits not intended to be connected together in service.
ii) 4 kV Additional tests for insulating encased meters of protective Class II
[for test in
item (a)]
a) Between, on the one hand, all the current and voltage circuits as well as the auxiliary circuits
whose reference voltage is over 40 V, connected together, and, on the other hand, earth;
b) A visual inspection for compliance with the conditions of 4.2.7; and
40 V [for test c) Between, on the one hand, all conductive parts inside the meter connected together and, on
in item (c)] the other hand, all conductive parts, outside the meter case that are accessible with the test
finger, connected together.
NOTES
1 The test in item (a) of Sl No. (ii) is to be carried out with the case closed, and the cover and terminal covers in place.
2 The test in item (c) of Sl No. (ii) is not necessary if the test in item (b) leaves no doubt.

24
 IS 15884 : 2010

Table 16 Insulation Resistance test

(Clause 5.4.6.4)
Test Voltage Point of Application of the Test Voltage I n su la t ion R esist a n ce
(1) (2) (3)
500 ± 50 V dc a) Between, on the one hand, all the current 5 MŸ
and voltage circuit as well as auxiliary circuits
whose reference voltage is over 40 V,
connected together, and, on the other
hand, earth
b) between circuit not intended to be 50 MŸ
connected together in service
NOTE — Where two or more voltage circuits are permanently joined together, the combination may be treated as one circuit
for this test.

c) If contact discharge is not applicable because IS 14700 (Part 4/Sec 3) under the following
no metallic parts are outside, then apply air conditions:
discharge with a 15 kV test voltage.
1) Voltage and auxiliary circuit energized
d) Meter in non-operative condition: with basic voltage,
2) Frequency band : 80 MHz to 2 000 MHz,
1) Voltage, current and auxiliary circuits shall
3) Test field strength : 10 V/m and
be unenergized
4) Test severity level : 4.
2) The aperture for the token acceptor, if
present, shall have a metal token inserted b) Without any current in the current circuit and
into it. current terminal shall be open circuit.
3) All voltage and auxiliary terminals shall be c) The application of the RF field shall not
connected together and the current produce change in register of more than x kWh
terminal shall be open circuit. and the test output shall not produce a signal
equivalent of more than x kWh. The value x is
e) After application of the electrostatic discharge derived from the following formula:
the meter shall show no damage or change of
information and shall stay within the accuracy x = 10-6.m.Vref.IMax
requirements of this standard.
where
f) Meter in operative condition: m = number of measuring element,
1) Voltage and auxiliary circuits energized with Vref = reference voltage in volts, and
reference voltage; and IMax = maximum current in amperes.
2) Without any current in current circuits and d) With basic current Ib and power factor equal
the current terminal shall be open circuit. to unity, at sensitive frequencies or frequency
g) Electrostatic discharge shall not produce a of dominate interest, the variation of error shall
change register of more than x kWh and the be within the limit given in Table 12.
test output shall not produce a signal 5.5.4 Fast Transient Burst Test
equivalent of more than x kWh. The value x is
derived from the following formula: The test shall be carried out according to IS 14700
(Part 4/Sec 4) under the following conditions:
x = 10 -6.m.Vref.IMax
a) Tested as table top equipment.
where b) Meter in operating condition:
m = number of measuring element, 1) Voltage and auxiliary circuits energised
Vref = reference voltage in volts, and with reference voltage.
IMax = maximum current in amperes. 2) With basic current in current power factor
unity.
h) Valid token shall be accepted.
c) Cable length between coupling device and
5.5.3 Test of Immunity to Electromagnetic HF Fields EUT : 1 m.
a) The test shall be carried out according to d) The test voltage shall be applied in common

25
IS 15884 : 2010

mode ( line to earth) to: impedance: 2;

1) the voltage circuit; g) Test voltage on auxiliary circuits with a
reference voltage over 40 V: 1 kV;
2) the current circuits, if separated from
voltage circuit; and h) Generator source impedance: 42;
3) auxiliary circuits if separated from voltage j) Number of tests: 5 positive and 5 negative;
circuit in normal operation. and
k) Repetition rate: maximum 1/min.
e) Test voltage on current and voltage circuit: 4 kV;
This test shall first be performed with the load switch
f) Test voltage on auxiliary circuits with a closed.
reference voltage above 40 V : 2 kV
The test shall then be repeated with the load switch
g) Duration of test: 60 s at each polarity. open.
The test shall be carried out first with the test load The application of the RF field shall not produce
and limits of variation in percentage error as given in change in register of more than x kWh and the test
Table 12. output shall not produce a signal equivalent of more
The test shall be repeated with the load switch open than x kWh. The value x is derived from the following
and therefore no test current flowing and with the formula:
load cables still connected. No change of the actual x = 10 -6.m. Vref.IMax
operating state or stored data is allowed. The meter
where
shall continue to operate correctly after the test
without any external intervention. m = number of measuring element,
Vref = reference voltage in volts, and
5.5.5 Radio Interference Measurement
IMax = maximum current in amperes.
The test for radio interference shall be carried out
according to IEC 62052-11. During the test, a temporary degradation or loss of
function or performance is acceptable.
The test shall be carried out with the load switch
closed and test current flowing. During the test the 5.6 Tests of Accur acy Requirements
normal behavior of the payment meter shall not be 5.6.1 General Test Conditions
disturbed.
To test the accuracy requirements as fixed under 4.6,
The test shall be repeated with the load switch open the following test conditions shall be maintained:
and therefore no test current flowing and with the
load cables still connected. No change of the actual a) The meter shall be tested in its case with the
operating state or stored data is allowed. The meter cover in position; all parts intended to be
shall continue to operate correctly after the test earthed shall be earthed;
without any external intervention. b) Before any test is made, the circuits shall have
been energized for a time sufficient to reach
5.5.6 Surge Immunity Test
thermal stability;
The test shall be carried out according to IEC 61000- c) In addition, for polyphase meters:
4-5, under the following conditions with meter in
operating condition: 1) The phase sequence shall be as marked
on the diagram of connections;
a) Voltage and auxiliary circuits energized with 2) The voltages and currents shall be
reference voltage; substantially balanced (see Table 17).
b) Without any current in the current circuits
and the current terminals shall be open 5.6.2 Test of Influence Quantities
circuit; It shall be verified that the influence quantity
c) Cable length between surge generator and requirements as fixed under 4.6.1 and 4.6.2 are satisfied.
meter: 1 m;
Tests for variation caused by influence quantities
d) Tested in differential mode (line to line);
should be performed independently with all other
e) Phase angle: pulses to be applied at 60° and influence quantities at their reference conditions (see
240° relative to zero crossing of ac supply; Table 18).
f) Test voltage on the current and voltage
5.6.2.1 Continuous magnetic induction of external
circuits (mains lines): 4 kV, generator source
origin 67 mT
26
 IS 15884 : 2010

Table 17 Voltage and Current Balance

(Clause 5.6.1)
Sl No. Polyphase Meter s C la ss 1 Class 2
(1) (2) (3) (4)
i) Each of the voltages between line and neutral or between ±1 percent ±1 percent
any two lines shall not differ from the average corresponding
voltage by more than
ii) Each of the current in the conductors shall not differ from the ±2 percent ±2 percent
average current by more than
iii) The phase displacement of each of these currents from the ±2° ±2°
corresponding line-to-neutral voltage, irrespective of the power
factor, shall not differ from each other by more than

The continuous magnetic induction of 67 mT ± 5 the magneto-motive force to be applied shall be

percent shall be obtained at a distance of 5 mm from generally 10 000 ampere-turns. However, considering
the surface of the pole by using the electromagnet the non-linearity of magnetization of the core, the
according to Annex J, energized with a dc current. ampere-turns might require slight adjustment to
This magnetic field shall be applied to all accessible achieve the desired output. This magnetic field shall
surfaces of the meter. The value of the magneto- be applied to all surfaces of the meter when it is
motive force applied shall be 1 000 AT (ampere-turns). mounted as for normal use. The influence of abnormal
magnetic fields shall not cause the meter to run slower
5.6.2.2 Continuous magnetic induction of external than 4 percent in comparison to normal condition.
origin 0.2 Tesla
NOTE — In the event of logging of abnormal magnetic
DC magnetic field of 0.2 tesla ± 5 percent may be induction with date and time, the positive variation may
obtained at a distance of 0.5 cm from the surface of be beyond the limit of 4 percent, but not exceeding a
power value equivalent to product of rated voltage and
the pole, by using the electromagnet according to
maximum current
Annex J, energized with a dc current. The value of

Table 18 Reference Conditions

(Clause 5.6.2)
Sl No. I n flu en ce Q u a n t it y R efer en ce Va lu e P er m issib le Toler a n ce for M et er s of C la ss

1.0 2.0
(1) (2) (3) (4) (5)

i) Ambient temperature Reference temperature ±2°C ±2°C

or, in its absence, 27°C
ii) Voltage Reference voltage ±1.0 percent ±1.0 percent
iii) Frequency Reference frequency ±0.3 percent ±0.5 percent
iv) Wave-form Sinusoidal voltages Distortion factor less Distortion factor less
and currents than: 2 percent less than: 3 percent
v) Magnetic induction Magnetic induction Induction value Induction value which
of external origin at the equal to zero which causes a causes a variation of
reference frequency variation of error not error not greater than
greater than 0.2 0.2 percent but should
percent but should in any case be smaller
in any case be smaller than 0.05 mT
than 0.05 mT
NOTES
1 If the tests are made at a temperature other than the reference temperature, including permissible tolerances, the results shall
be corrected by applying the appropriate temperature coefficient of the meter.
2 The test consists of:
a) for a single-phase meter, determining the errors first with the meter normally connected to the mains and then after
inverting the connections to the current circuits as well as to the voltage circuits. Half of the difference between the two
errors is the value of the variation of error. Because of the unknown phase of the external field, the test should be made
at 0.1 Ib at unity power factor and 0.2 Ib at 0.5 power factor; and
b) for a three-phase meter, making three measurements at 0.1 Ib at unity power factor, after each of which the connec-
tions to the current circuits and to the voltage circuits are changed over 120° while the phase sequence is not altered.
The greatest difference between each of the errors so determined and their average value is the value of the variation
of error.

27
IS 15884 : 2010

5.6.2.3 Magnetic induction of external origin 0.5 mT Imax and UPF. Although this verification is not
required for meters having test output in the from of
Magnetic induction of external origin of 0.5 mT high resolution register, a long period registration
produced by a current of the same frequency as that test shall be performed at this test point to verify
of the voltage applied to the meter and under the conformity of registration error, as indicated by the
most unfavorable conditions of phase and direction display of the meter and as distinct form any other
shall not cause a variation in the percentage error of external display used for testing purpose within the
the meter exceeding the values shown in this table. limits specified in Table 9.
The magnetic induction shall be obtained by placing
the meter in the centre of a circular coil, 1 m in mean 5.6.6 Interpretation of Test Results
diameter, of square section and of small radial
thickness relative to the diameter, and having 400 AT. During type tests, certain test results may fall outside
the limits indicated in Tables 10 and 11, owing to
5.6.2.4 Magnetic induction of external origin 10 mT uncertainties of measurements and other parameters
capable of influencing the measurements. However,
ac magnetic induction of 10 mT produced by a current if by one displacement of the zero line parallel to
of the same frequency as that of the voltage applied itself by no more than the limits indicated in Table
to the meter and under most unfavourable conditions 19, all the test results are brought within the limits
of phase and direction shall not cause a variation in indicated in Tables 10 and 11, the meter type shall be
the percentage error of the meter exceeding the considered acceptable.
values shown in the Table 12.
Table 19 Inter pretation of Test Results
ac magnetic induction shall be obtained in a circular Sl No. C on d it ion of C la ss of M et er
coil and the meter shall be placed in various Accep t a b ilit y
orientation in the center of a circular coil (O.D.: 1 2
400 mm, I.D.: 320 mm, depth: 45 mm, Ampere-turns: (1) (2) (3) (4)
2800, 10 SWG Copper wire) produce magnetic i) Permissible displacement 0.5 1.0
induction of 10 ± 10 percent milli-Tesla in the central of the zero (percent)
region (covering an area of half the diameter of either
of the coil surface. The influence of abnormal 5.6.7 Repeatability of Error Test
magnetic fields shall not cause the meter to run slower Test shall be carried out at 0.05 Ib and Ib at UPF load
than 4 percent in comparison to normal condition. under reference conditions. Twenty error samples
NOTE — In the event of logging of abnormal magnetic shall be taken at time intervals of 30 min. Identical
induction with date and time, the positive variation may test condition shall be maintained through out the test
be beyond the limit of 4 percent, but not exceeding a
power value equivalent to product of rated voltage and For acceptance test six error tests may be carried out
maximum current at time interval of at least 5 min.
5.6.3 Test of No-Load Condition 5.7 Test of Keeping Time
For this test the current circuit must be open circuit It shall be verified the time drift and battery life as
and a voltage of 115 percent of the marked voltage fixed under 4.6.6 are satisfied.
shall be applied to the voltage circuits.
5.8 Test of the Load Switch
The minimum test period shall be 60 000/k minutes,
where k = number of pulses emitted by the output The load switch shall be tested to fulfil the
device of the meter per kilowatt-hour. requirement of 4.4.3. The meter accounting process
is handled in the payment meter itself. In general in
During this test the test output device of the meter the prepayment mode the metered kWh consumption
shall not emit more than one pulse. leads to a proportionate decrementing of the available
5.6.4 Test of Starting Condition credit register. Time-based charges such as standing
charges also decrement the available credit register
It shall be verified that the starting requirements as where applicable. All such decrementing can reduce
fixed under 4.6.3.3 are satisfied. the available credit through zero to negative values
unless further token credit is bought and loaded.
5.6.5 Test of Meter Constant When the available credit falls to zero the load switch
It shall be verified that the relation between the test is opened automatically. Switching on of the load
output and the indication on the display complies switch is only enabled when token credit is again
with the marking on the nameplate. loaded and the available credit becomes positive.
Testing these other functions validates the meter
This shall be verified at one test point, preferable at accounting process. The load switch interrupt/

28
 IS 15884 : 2010

restore conditions may be different where there is When testing payment meters under 4 and 5
additional functionality such as emergency credit, (including any sub-clauses) a record of all relevant
or token credit partially allocated for repayment of readings and status shall be made before and after
emergency credit debt; they will also be different for each test or sequence of tests. The beginning and
alternative payment modes end readings shall then be reconciled with the testing
procedure and duration to confirm the integrity of
5.9 Test of Consumption Based Char ging Functions the meter accounting process. 6.2 gives further
Where application-specific non-interruption periods details of these requirements.
or emergency credit facilities are incorporated in a NOTE — Refer to informative Annex A for some general
payment meter they shall be disabled before carrying functional requirements, tests, and testing guidelines for
out the following test. The consumption-based payment meters, which may, for example, be considered
and applied when agreeing overall evaluation and system
charge function shall be tested for a sufficient amount
testing requirements between manufacturer and purchaser.
of energy consumption to ensure correct deductions Clause A-1 (including all sub-clauses) gives basic functional
from the available credit. Where the payment meter requirements and tests for the prepayment mode of
operates in monetary units an appropriate price per operation. For additional features and options and other
payment modes, the specifying of requirements and testing
kWh shall be set. Where the payment meter includes
is more diverse and so an outline of the approaches that
time-based charging functions they shall be disabled may be adopted is given in A-2 and A-3 (including any
for this test. Sufficient available credit shall be sub-clauses). Further evolution of the functional
provided and noted, and then maximum load shall be requirements and testing arrangements in Annex A is
anticipated and so they do not have to be assessed during
applied to the payment meter for the necessary period
payment meter type tests.
of time. The advance of the cumulative kWh register
shall correspond to the deduction of available credit 6.2 Robustness of Meter Accounting Pr ocess
that has then taken place. Where the payment meter
operates in monetary units the test shall be repeated Although acceptable error limits are defined for
with a representative range of settings of price per accuracy of energy measurement under nominal and
kWh, including the maximum setting. Where the influence conditions for electricity meters, there is
payment meter includes multi-rate kWh registers not an equivalent acceptable error in the calculation
these tests shall be repeated for each rate of the kWh of available credit on payment meters. In addition,
registers. the settings and current operating modes of the meter
shall not change spontaneously as a result of testing.
NOTE — For the purpose of this test the chosen values Therefore when testing a payment meter under 4
of tariff rate and credit values shall be capable of a result
and 5 (including any sub-clauses):
with resolution less than one percent.

5.10 Test of Time-Based Char ging Functions a) a record shall be made prior to each test or
sequence of tests of all relevant registers,
With a suitable tariff rate per kilowatt, the payment settings, status, and active modes, including
meter shall be credited with one currency units or readings of all energy registers, readings of
energy credit unit and shall be run on a suitable load all energy-based rate settings (where
until the switch opens. The difference in the energy monetary-based credit is used), readings of
display before and after the test shall be recorded. all credit and debt values and the modes that
are active; and
NOTE — For the purpose of this test the chosen values
of tariff rate and credit value shall be capable of resolving
b) where the meter includes a timekeeping
the result to at least one percent.
function readings of all time-based charge or
The meter shall disconnect the supply, when the credit settings (where used), meter time/date
available credit has been consumed. The meter shall and offset of meter time from the time on the
be able to decrement the available credit register past reference clock.
zero, into negative values, if the load is not
disconnected when the available credit has been During each test, the amount of any token credit
consumed for application specific reason. loaded into the meter shall be recorded.

6 FUNCTIONAL REQUIREMENTS At the end of each test or sequence of tests, these

readings shall be recorded again. Further recordings
6.1 Gener al may also be made when any settings are changed as
part of the tests.
The general requirements for operation of payment
meter functionality over the temperature ranges and Unless specifically stated otherwise, a test or
voltage ranges are given in 4.3.1 and 4.4.2.1 and sequence of tests is passed only if the following
their sub-clauses. conditions are also met:

29
IS 15884 : 2010

a) Energy measurement is within the error limits g) The meter’s display is functioning correctly;
specified for that test; h) Any pushbuttons on the meter operate
b) The meter’s timekeeping accuracy is within correctly;
acceptable limits for the timekeeping mode and j) Token acceptance of a valid token occurs
the nature of the test; on the first or second presentation. This
c) There are no changes in any energy-based rate shall not be tested until satisfaction of the
setting; criteria listed above has been confirmed; and
d) There are no changes in any time-based k) The load switch operates correctly.
charge or credit setting;
Unless specifically stated otherwise, a maximum of
e) Any changes in credit and debt values are 1 energy-based rate setting and a maximum of 1 time-
exactly accounted for by energy measured by based charge or credit setting shall be active for the
the meter during the test × the value of the duration of any test.
active energy-based rate setting and: duration
of time recorded by the meter × the value of NOTES
the active time-based charge or credit setting 1 It is acceptable for 2 or more time-based charge settings
and; the value of any token credit accepted (for example standing charge and debt collection) to be
active during a test, provided that their combined value
by the meter during the test remains constant throughout the test.
NOTE — Verification of this value requires the 2 If for some tests, it is required that the rate per kWh for
ability to verify the value of valid credit on a the active rate is to be set to zero, then the rate per kWh
token carrier before and after it has been presented for non-active rates shall be set to non-zero values.
to the meter.
3 Where the meter is operating within its limit range of
f) There are no changes to any active modes operation, but outside its extended operating range, a valid
in the meter; credit token that is presented to the meter shall either be
accepted correctly, or be rejected or ignored without
modifying its information.

ANNEX A
(Clause 6.1)
FUNCTIONAL PERFORMANCE
(Informative)

A-1 BASIC FUNCTIONALITIES — PREPAYMENT The core functionalities are covered in A-1.2 and
MODE their testing includes the sequence of operations and
checks in A-1.3 that covers the basic functionality
A-1.1 Gener al of the payment meter. The meter’s behaviour will be
This Annex covers some functionalities, tests, and dependent upon both hardware and software, as well
testing guidelines for payment meters, which may as on influence factors. The sequence of tests is
for example be considered and applied when agreeing therefore repeated for combinations of the main
any overall evaluation and system testing influence factors, which are supply voltage and
requirements between manufacturer and purchaser. ambient temperature. Further basic functionalities are
The basic functionalities are given here for the tested under reference conditions, unless otherwise
prepayment mode of operation, and are separate to stated, or are design considerations.
the normative requirements given in the main section The payment meter should be mounted as for normal
of this standard. For additional features and options service, including in a specified matching socket
and other payment modes, the specification of where applicable. Verification should be carried out
requirements and testing is more diverse and under reference conditions unless otherwise stated.
therefore an outline of the approaches that may be Where ‘maximum meter load’ is stated, this should
adopted is given in A-2 and A-3 (including any sub- be taken as balanced at Vref, IMax, and unity power
clauses). factor.

30
 IS 15884 : 2010

Where ‘minimum meter load’ is stated, this should Under normal conditions, any invalid token should
be taken as balanced at Vref, 0.05 Ib and unity power be rejected or ignored by the payment meter, and
factor. should not result in any change to information in the
accounting registers in the meter. Rejection or
A-1.2 Pr epayment Mode — Cor e Functionalities ignoring should not lead to any token cancellation
A-1.2.1 Token Acceptance or to any change of information on the token carrier,
that is the token should remain valid for use in its
The payment meter should handle valid and invalid intended application or with the correct meter.
tokens in accordance with the following
requirements. The payment meter should always reject or ignore
an invalid token under any prevailing conditions;
The acceptance of a valid token should always result there should be no prevailing conditions within the
in the exact amount of credit on the token carrier limit range of operation under which an invalid token
being transferred to the appropriate register(s) in the can be accepted.
payment meter, and the available credit value in the
meter should be incremented by exactly this amount Where prevailing conditions prevent the acceptance
(see Note 1). or rejection of a token, it should be ignored and both
the token and the meter’s accounting register(s)
Acceptance of the token should be indicated on the should be left unchanged.
payment meter and should also always result in token
cancellation so that this token is then invalid and Verification of token rejection or ignoring should be
cannot be accepted again. However, reusable token carried out at both zero current and at IMax and unity
carriers may then be loaded with a new purchase of power factor. Token rejection or ignoring should be
token credit and become valid again. verified at the limits of the extended operating range
of supply voltage, and the limits of the specified
Where prevailing conditions prevent the acceptance operating range of temperature.
of a valid token, it should be rejected as an invalid
token, or ignored and left unchanged. A valid token A-1.2.3 Meter Accounting Process
that has previously been rejected or ignored should The meter accounting process is handled in the
be capable of being accepted when prevailing payment meter itself. In general, in the prepayment
conditions subsequently allow. mode, the metered kWh consumption leads to a
Verification of token acceptance should be carried proportionate decrementing of the available credit
out at both zero current and at IMax and unity power value. Time-based charges such as standing charges
factor. Token acceptance should be verified at the also decrement the available credit value where
limits of the extended operating range of supply applicable. All such decrementing can reduce the
voltage, and the limits of the specified operating available credit through zero to negative values
range of temperature (see A-1.3, A-1.4 and A-1.5). unless further token credit is bought and loaded.
When the available credit falls to zero, the load switch
This should apply without the invocation of certain is opened automatically. Switching on of the load
additional facilities that may be present in the meter, switch is only enabled when token credit is again
such as emergency credit, reserve credit, or token loaded and the available credit becomes positive.
credit partially allocated for repayment of emergency Testing these other functions validates the meter
credit debt. accounting process.
Token acceptance should also be verified as part of The load switch interrupt/restore conditions may be
some of the other requirements and tests given in 4 different where there is additional functionality such
and 5 (including any sub-clauses). as emergency credit, or token credit partially
NOTES allocated for repayment of emergency credit debt;
1 For some payment meter implementations using they will also be different for alternative payment
magnetic card token carriers, the token carrier acceptor modes (see A-2 and its sub-clauses).
applies a mark to the token carrier to indicate that token
acceptance has been completed. A-1.2.4 Collection of Consumption-Based Charges
2 For some payment meter implementations, an audible
signal is given to indicate that token acceptance has been
Where application-specific non-interruption periods
completed. or emergency credit facilities are incorporated in a
payment meter, they should be disabled before
A-1.2.2 Token Rejection carrying out the following test.
The payment meter should handle valid and invalid The consumption-based charge function should be
tokens in accordance with the following tested for a sufficient amount of energy consumption
requirements.
31
IS 15884 : 2010

to ensure correct deductions from the available credit. Once the load is interrupted by such meter
Where the payment meter operates in monetary units, accounting process action, the load switch should
an appropriate price per kWh should be set. Where only be operable to restore the load after a further
the payment meter includes time-based charging appropriate manual intervention, for example by
functions, they should be disabled for this test. pressing a push-button or by manually presenting a
Sufficient available credit should be provided and further credit token. This should be true for any
noted, and then maximum load should be applied to conditions of the meter accounting process and
the payment meter for the necessary period of time. available credit, and for any supply voltage or
The advance of the cumulative kWh register should temperature within the limit ranges of operation.
correspond to the deduction of available credit that
has then taken place. A-1.2.7 Effect of Power Outages

Where the payment meter operates in monetary units, In the event of a power system outage interrupting
the test should be repeated with a representative the power supply to the payment meter, there should
range of settings of price per kWh, including the be no malfunction in the operation of the meter
maximum setting. Where the payment meter includes accounting process. All registers should retain their
multi-rate kWh registers, these tests should be values prior to the power outage. For test purposes,
repeated for each rate of the kWh registers. any time-based charging functions should be
inhibited. See A-1.3 for testing.
A-1.2.5 Collection of Standing Charges
NOTE — See 5.4.2.2 for the influence of short voltage
Where the payment meter incorporates a standing dips and interruptions.
charge collection facility the following should apply:
A-1.3 Cor e Functional Tests within Voltage and
The available credit value should be decremented at Temper ature Range Limits
the correct rate set for the time-based charges. The
The core functions of the payment meter should also
implementations of such charge deductions from
available credit will vary between different payment be tested and requirements should be met for lower
meter types (for example deductions being made per and upper limits of the specified operating
hour or per day); appropriate choices of testing temperature range and lower and upper limits of the
periods should be made. extended operating voltage range.

Where the payment meter includes any other time- The test sequence is therefore carried out four times
based charging functions, then they should be under these conditions:
disabled for this test, and the meter load should be a) Lower temperature limit + lower voltage limit
zero. An appropriate standing charge should then
be set to permit verification of accurate deduction b) Lower temperature limit + upper voltage limit
from available credit over a suitable test period. The c) Upper temperature limit + lower voltage limit
choice of settings will be dependent upon the d) Upper temperature limit + upper voltage limit
specific implementation of the standing charge
facility in the payment meter. The following test sequence should be used:

The above test should then be repeated at maximum a) The payment meter should be in the
meter load and, where the payment meter operates in prepayment mode and mounted for normal
monetary units, an appropriate price per kWh should service, including in a specified matching
be set. The total deduction from available credit over socket where applicable. Where the meter
the test period should then be correct in respect of includes collection of time-based charging
both standing charge and kWh register advance. functions, they should be disabled until the
Where the payment meter includes multi-rate kWh appropriate part of these tests. Where
registers these tests should be repeated for each rate application-specific non-interruption periods or
of the kWh registers. emergency credit facilities are incorporated, they
should be disabled throughout these tests.
A-1.2.6 Interruption and Restoration of the Load
b) Where the payment meter operates in
The meter should normally interrupt the load when monetary units, an appropriate price per kWh
the available credit has been consumed. should be set. The meter should be prepared
The meter should be able to decrement the available by applying a load until the available credit is
credit value past zero, into negative values, including exhausted and the load switch opens
where for application-specific reasons the load is not automatically. Readings of the cumulative kWh
interrupted when the available credit has been register and available credit value are then
consumed. recorded. The supply voltage is then removed.

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c) The meter is cooled to the lower temperature voltage but within the limit range of operation (that
limit and the temperature is allowed to is from 0.0 to 0.8 Vref) are given in 4.4.2.4.
stabilise. The lower supply voltage is then
applied with zero load current and after one The following tests should be carried out under
minute, the register and value readings are reference conditions, with the supply voltage to the
again recorded, and checked for correct payment meter varying between zero and 0.8 Vref.
retention. An invalid token is then presented The following test sequence should be used:
and checked for correct rejection. a) The payment meter should be in the
d) A valid token carrying a suitable amount of prepayment mode and mounted for normal
credit should then be presented to the meter service, including in a specified matching
to check token acceptance. The readings are socket where applicable. Where the meter
then recorded and checked for the correct includes collection of time-based charging
advance of available credit. The load switch functions, they should be disabled throughout
should now be closed, or can be closed these tests. Where application-specific non-
manually, depending on the design. interruption periods or emergency credit
facilities are incorporated they should be
e) The supply voltage is now removed for 5 min
disabled throughout these tests. Where the
and then restored with zero load current. The
payment meter operates in monetary units, the
readings are then recorded and checked for
maximum price per kWh should be set. In
correct retention.
respect of any function covered by the note
f) A load of IMax and unity power factor is then in 4.4.2.4 being included in the payment meter,
applied so that the available credit reduces this function may be inhibited where relevant.
and eventually the load switch opens
automatically. The readings are then recorded b) The meter should be arranged to have a
and their changes checked for correct negative value of available credit, such as to
reconciliation. In the case of a multi-rate meter, ensure that the load switch is open. Readings
this test may be carried out for a single rate only. of the cumulative kWh register and available
credit value are then recorded. The supply
g) Where the payment meter includes a facility voltage is then removed.
for collection of standing charges, the
following test should apply. Where any other c) The supply voltage should be increased from
time-based charging functions are included, zero at a steady and progressive rate of
they should be disabled for this test. An approximately 1 percent of Vref per second
appropriate standing charge should be set to with no load current, dwelling at each of the
permit verification of accurate deduction from following levels for 60 s: 20 percent Vref 40
available credit over a suitable test period. The percent Vref, 60 percent Vref, 80 percent Vref.
choice of settings will be dependent upon the While at 80 percent Vref it should be verified
specific implementation of the standing charge that the load switch is in the correct position.
facility in the payment meter. A suitable token d) After 60 s at 80 percent Vref the supply voltage
amount should then be loaded into the meter should be decreased at a steady and
and the readings recorded. The meter should progressive rate of approximately 1 percent of
then remain under voltage with zero current Vref per second with no load current, dwelling
for a suitable period of time, which should be at each of the following levels for 60 s: 70
measured with a reference clock. Upon the percent Vref, 50 percent Vref, 30 percent Vref,
completion of this period, the readings should 10 percent Vref, before reaching zero.
be recorded, and their changes checked for
correct reconciliation. e) After 10 s at zero voltage, a supply voltage of
0.8 Vref should be applied to the meter and the
h) Test steps (a) to (g) should then be repeated readings of the cumulative kWh register and
for the lower temperature limit, but at the available credit value then recorded.
upper voltage limit.
Sufficient token credit should then be loaded to
j) Test steps (a) to (h) should then be repeated
ensure that the load switch is closed. The readings
at the upper temperature limit.
of the cumulative kWh register and available credit
A-1.4 Functional Tests within the Limit Range of value are then recorded again, and the supply voltage
Oper ation with Voltage is then removed.
The requirements for payment meter operation The test sequence in (c), and (d) is then repeated,
outside the extended operating range of supply with the load switch closed but no load current

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IS 15884 : 2010

applied. After (d) and 10 s at zero voltage, a supply specific tokens for single use, the payment meter
voltage of 0.8 Vref should be applied to the meter and should ensure that no customer token intended for
the readings of the cumulative kWh register and single use may be actioned more than once, including
available credit value then recorded. where token acceptance has been interrupted.

After these tests, the status of all registers, values, A-1.6.2.1 Test for rejection of duplicated tokens
and parameters associated with the meter accounting
Connect the meter as for normal use, with zero load.
process should be seen to have continued to be valid
Generate a customer token, and a duplicate of the token.
and free of corruption. Any internal timekeeping
facility should be seen to have continued to maintain Present the first token, and verify that the meter has
timekeeping. Any unexpected or uncontrolled accepted the token.
behavior occurring during these tests should be
noted and attached to the test report for future Then present the duplicated token. Verify that the
reference. meter rejects this token, and where a virtual token is
used, that the meter issues an appropriate message.
A-1.5 Functional Tests within the Limit Range of
A.1.6.3 Rejection of Valid Tokens when Available
Oper ation with Temper ature
Credit is Saturated
The core functions of the payment meter should also
Where a valid token presented to the payment meter
be tested and requirements should be met for lower
would result in the amount of available credit
and upper limits of the limit range of operation with
exceeding the maximum amount possible in the meter,
temperature and with the supply voltage at the
then the token should be rejected. The token should
reference voltage Vref in each case.
not be erased or invalidated; presentation of a virtual
The test sequence is therefore carried out two times token should result in an appropriate message being
under these conditions: returned from the meter. It should be possible for the
token to be presented and accepted at a later time
a) Lower temperature limit + reference voltage when conditions then allow.
b) Upper temperature limit + reference voltage
A-1.6.3.1 Test for saturation of available credit in
The test sequence in A-1.3(a) to (f) should be used, the meter
first for the lower temperature limit, then repeated
Connect the payment meter as for normal use, with
for the upper temperature limit. The test at A.1.3(g)
almost the maximum amount of available credit
is not required; however any real-time clock should
already present, and with zero load.
continue to maintain timekeeping during the test
sequences. Generate a token that, when added to the current
available credit, would give a total amount of
A-1.6 Pr epayment Mode — Token Handling and
available credit greater than the maximum amount
Data Integr ity Requir ements
that the meter is declared as being capable of
A-1.6.1 Interruption to Token Acceptance handling.

Where a token carrier acceptor is fitted to a payment Present this token to the payment meter. Verify that
meter, a token carrier will be inserted into the token the meter rejects the token, and where appropriate
carrier acceptor and normally the data transfer that it has not been physically marked. For virtual
process will be completed before token carrier tokens, verify that an appropriate message is returned
withdrawal takes place. Where the token carrier can from the meter.
be withdrawn from the acceptor before the data Apply a load to reduce the available credit
transfer process is completed, then the meter should sufficiently to allow for acceptance of the token.
be designed such that data on the token carrier
should not be corrupted or lost and any data Present the token again and verify that the meter
transferred to the payment meter should not be now accepts it correctly.
actioned until the token transaction is subsequently
A-1.6.4 Secure Storage of Credit
completed. Data corruption on the token carrier is
permitted if the payment meter is able, from the The payment meter should be designed such that
information available, to reconstruct the appropriate the amount of credit stored in the meter cannot be
data on the next insertion of the token carrier into changed other than by legitimate means, for example
the token carrier acceptor. with a valid token or message.
A-1.6.2 Rejection of Duplicate Tokens A-1.6.5 Tariff Security
Where payment system operation is based on meter- Where the payment meter requires changes to tariff

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information held within it at any time, it should be e) Token credit partially allocated for repayment
designed such that the tariff information stored in of emergency credit debt;
the meter cannot be changed other than by legitimate f) Non-interruption periods;
means, for example with a valid token or message.
g) Load-limiting mode;
A-1.6.6 Reading and Setting Facilities h) Reverse-running interruption;
The payment meter may incorporate a service j) Multiple-block tariffs; and
interface for extracting meter reading status and k) Collection of agreed debt.
diagnostics information, and for making changes to
payment mode, settings, security keys, or test modes In general, the testing of functionality for these
to meet overall system requirements. These actions modes and options are somewhat dependent upon
may be implemented via the token interface or via a the specific details of implementation and specific
separate service interface, possibly in conjunction functional test sequences are likely to be needed.
with the push button(s) and display or indicators. In A general test sequence for the last point is given
such cases, it should be designed such that it should in A-2.3.
not be possible to make any changes or resetting to A-2.3 Collection of Agreed Debt
the meter other than by legitimate means, for example
with a valid token or message. Where the payment meter incorporates a specific
debt collection facility, the following should apply:
A-2 ADDITIONAL FUNCTIONALITIES
Where the payment meter includes any other time-
A-2.1 Gener al based charging functions, they should initially be
A payment meter may provide for additional features disabled for this test, and the meter load should be
and options, and alternative modes of operation. The zero. An appropriate debt collection rate (and where
detailed specification of such additional functionality applicable, an amount of agreed debt) should then
may be manufacturer specific or of a proprietary be set to permit verification of accurate deduction
nature, or be agreed between purchaser and supplier, from available credit over a suitable test period. The
or be defined by user organizations or standards. choice of settings will be dependent upon the
specific implementation of the debt collection facility
Functional performance and testing guidelines and in the payment meter. Where applicable, the debt
schedules will then need to be based on the relevant collection should cease when the agreed debt amount
specifications, and may need to take account of the has been deducted from the available credit.
specific implementation and system requirements. In
these circumstances, confirmation of compliance by The above test should then be repeated at maximum
the manufacturer or relevant organization may be meter load and maximum debt collection rate and,
appropriate, or inspection and testing may be carried where the payment meter operates in monetary units,
out jointly where so agreed between purchaser and an appropriate price per kWh should be set. Where
supplier. applicable, an appropriate amount of agreed debt
should be set such that debt collection is to terminate
Details of additional functionalities and tests are before the end of the test period. The total deduction
under consideration and include the following from available credit over the test period should then
aspects. Some aspects of payment system be correct in respect of both debt collection and kWh
functionality may be dependent upon the associated register advance. Where the payment meter includes
infrastructure and management system. Such cases multi-rate kWh registers, these tests should be
are not covered in this annex. repeated for each rate of the kWh registers.
A-2.2 Requir ements for Other Modes of Oper ation Where the payment meter also includes collection of
standing charges, the test at maximum load should be
Since the main aspects of hardware-dependent repeated with the standing charge also set at maximum.
functionality and performance are checked in the
prepayment mode, the software-dependent A-2.4 Time-of-Use Tar iff Facilities
functionality of any alternative modes of operation
may be checked under reference conditions. This may A-2.4.1 External Tariff Control
apply to any of the following: Where the meter includes arrangements for setting
a) Credit limit mode; up the tariff register operation and displays, this
should only be possible by legitimate means.
b) Fixed payment mode;
c) Budget mode and reserved credit; Checks of correct tariff register operation and
displays should be made for each permissible
d) Emergency credit;
combination of tariff control input signals (that is
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IS 15884 : 2010

for each tariff rate). Checks of consumption based time and tariff status evident after the outage period.
charging should be made as in A-1.2.4. Where the meter includes facilities for storing a new
tariff/charging program for adoption from a defined
A-2.4.2 Internal Tariff Control future date, then this action should be checked,
Where an internal real-time clock is fitted for time- including with unpowered operation over change of
of-use tariff control, it should be possible to set the year and 29 February and summertime changes during
time, but only by legitimate means. It should also be the pending period, and with power outages applied
possible to set the tariff time program and tariff at the time the new tariff/charging program is due to
register displays, but only by legitimate means. be adopted.

Checks of correct tariff register operation and Where auxiliary output switches are fitted for time-
displays should be made for each tariff rate, including of-use tariff purposes, their correct operation in
checks of consumption-based charging as in A-1.2.4. response to these test programmes and rate changes
should be included in these checks.
The correct operation of the tariff time program and
A-3 SYSTEM COMPLIANCE REQUIREMENTS
tariff register displays should be checked by setting
appropriate test program that exercise each rate, The payment meter is operated as part of an overall
weekday type, holiday type, and monthly or seasonal payment system, and the token interface, service
segment, where included. The checks should include port, or any remote communications port may be
correct roll-over for the beginning of each new type involved in data exchanges for both payment and
of tariff day, including at end of year and for 29 system management purposes. The detailed
February where appropriate, as well as any specification of these data exchanges may be
summertime begins/ends dates. The manufacturer manufacturer-specific or of a proprietary nature, or
should state any restrictions that may apply when be agreed between purchaser and supplier, or be
setting times or dates to make these checks, the date defined by user organizations or standards.
range over which the calendar function is tested
should be consistent with the reasonable expectation The overall system requirements and payment meter
compliance tests will then need to be based on the
of the life of the meter. The required calendar date/
relevant system specification and system testing
weekday functionality of the internal real-time clock
procedures. In these circumstances, confirmation of
should also be included as part of these checks.
system compliance by the manufacturer or a relevant
The checks should also include unpowered organization may be appropriate.
operation of the meter over any relevant critical
The details of these system-dependent requirements
periods including change of season, change of year,
and related system compliance tests are not covered
over 29 February where appropriate, and over
in this standard.
summertime begins/ends dates, with correct date/

ANNEX B
[Foreword; and Clause 3.8.5 (Note 2)]
REFERENCE MODEL FOR A PAYMENT METER
(Informative)

B-1 GENERAL representation of functionality and becomes concrete

only once it is deployed in a specific instance of a
This informative annex serves to draw attention to payment meter. It essentially serves to model and
the core functions that are found in a payment meter, define the workings of the payment meter. A particular
which should be taken into consideration while function may be implemented with any combination
performing the type tests in the normative part of of its sub-classified functions or with multiple
this standard. Particular attention should be given instances of the same sub-class. For example, a
to their proper functioning under abnormal influence demand tariff may combine 3 time-based tariff rates
conditions such as fault currents, voltage variation, with 2 consumption-based tariff rates with 1 monthly
temperature variation and EMC. standing charge and a tax. Multiple instances of the
The payment meter is one of the system entities that same function class are also possible. For example, a
embodies certain functions and certain processes, payment meter may hypothetically implement a units-
which together create the payment meter application based accounting function together with a currency-
process. A function definition is an abstract based accounting function, the one being for

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 IS 15884 : 2010

consumption charges and the other for debt recovery B-2 GENERALIZED PAYMENT METER INSTANCE
charges (see also B-3.4). A clear distinction has to
be made between the concept of a function and that In this instance, the single-part payment meter is
of an object and also in understanding their mutual arranged as a plug-in unit for use in a matching socket
relationship. A function is an abstract definition of a (see Fig. 1). The electrical connections between the
capability that may be embodied in an object, where two parts are made by means of suitable plugs and
it then manifests as an instance of the function. An matching sockets. Once the two parts are properly
object is an entity (physical component, device or installed and mechanically locked together, a suitable
object-orientated model that embodies one or more seal is installed to prevent unauthorized access to
functions, giving it the capability to do things the supply terminals and load terminals in the socket.
according to those functions. It may also require During installation, the supply network is connected
several components in order to realize a specific onto the supply terminals and the consumer’s load
function in a payment meter. For example: the load- circuit is connected to the load terminals in the
side terminals, plus the load switch, plus the socket. It can be seen that the load current passes
electronic driver circuitry, plus the firmware in the through the measurement element and also through
microprocessor, plus the memory storage space, all the load switch contacts in the active part of the
of which in combination embody the Delivery payment meter, such that the electrical energy being
function. consumed in the consumer load circuit can be

FIG. 1 GENERALIZED BLOCK DIAGRAM OF A PAYMENT METER INSTANCE

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IS 15884 : 2010

measured and that the supply can be interrupted consumption and optionally according to auxiliary
when the available credit runs out. charges, such as standing charges, debt recovery
and taxes. Conversely, the meter accounting process
The power supplies for the internal workings of the increments the available credit in accordance with
payment meter are derived from the mains supply in purchased credit or in accordance with other credit
this instance and are protected against the influence sources, such as emergency credit, that may be
of electro-magnetic disturbances by means of conditionally released by the meter accounting process.
suitable suppression circuits.
A real-time clock with an operational reserve (backup
Measurements from the measurement element are battery) typically provides date and time information
passed on to the storage and control functions, to the meter accounting process for the scheduling of
typically realized by means of a microprocessor with time-based charges and release of time-based credit.
supporting memory devices. The measurements are
cumulatively stored and are also passed on to the The user interface facilitates operating the meter by
meter accounting process for decrementing the various users that interact with the meter from time
available credit. to time. Examples of typical users are: the meter
manufacturer, the installation technician, the
When the available credit reaches zero, the meter maintenance technician, the meter inspector, the
accounting process automatically causes the load meter reader and the consumer. Besides the already
switch actuator to operate such as to interrupt the supply described token carrier interface and the optional
to the consumer load circuit. The consumer then has to manually operable load switch actuator, various push
purchase more credit in order to replenish the available buttons and a display are also typically provided on
credit before he is able to consume more energy. the front panel of the payment meter in order to input
Credit is purchased by the consumer at a vending information to the various processes in the payment
point, which is loaded onto a suitable token carrier meter and to view the results from some of these
for him to enter into the payment meter by means of processes. Examples of typical display values are:
the token carrier interface. Examples of typical token available credit, cumulative total consumption, date
carriers are magnetic cards, barcodes, numeric strings and time, tariff rates and register values.
printed on paper slips and solid-state memory An optional diagnostics/service interface may be
devices such as smart cards and memory key devices. provided by the payment meter, which may be located
Correspondingly, typical token carrier interfaces are on the front or the back of the meter. An example of
magnetic card readers, barcode readers, keypads, such an interface is an infrared port on the front panel
memory key readers and smart card readers. or an electrical connector for direct local connection
Certain reusable token carriers also have the to a diagnostic tool like a hand-held-unit.
capability to be loaded with information by the A test output is usually provided on the front panel
payment meter and to transfer the information to the of the payment meter and takes the form of a lamp,
vending point on the next occasion that the which gives out visible light pulses in proportion to
consumer goes to purchase more credit. This the energy being measured by the metering function.
information typically comprises consumption This enables external reference equipment to verify
quantities, various accumulated charges performed the metrological accuracy of the payment meter.
by the meter accounting process and the technical
status of the payment meter. This allows the Many configuration variations of the generalized
management system to perform an accounting audit instance of a payment meter are possible. One
on, for example, credits purchased versus actual example is a single part payment meter, where the
consumption and auxiliary charges transacted at the terminals are integrated into the same case as the
payment meter. All information loaded onto a token active part. Another example is a two-part payment
carrier is usually encrypted to prevent tampering and meter where the user interface is separated from the
fraudulent activities. Once the available credit is active part and remotely located from each other.
replenished, the meter accounting process will either
automatically cause the load switch actuator to B-3 FUNCTIONS IN A SINGLE-PART PAYMENT
operate or to optionally enable it to be manually METER
operated by the consumer in order to restore power B-3.1 Gener al
to the consumer load circuit. Manual operation is
usually performed by operating a mechanical lever that Clauses B-3.2 to B.3.11 should be read alongwith
is accessible on the user interface of the payment meter. Fig. 2 in order to gain a more detailed understanding
of the functions and processes found in payment
The meter accounting process reduces the available systems in general and in payment meters in
credit according to tariff charges for actual particular.

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B-3.2 Meter Application Pr ocess functioning of indicators and display devices; of the
load switch; of the token reading interface; of the
The meter application process coherently joins integrity of the memory recording registers; of the
together the functions deployed in the payment meter meter accounting function; of the data transport
and controls the behavior of the payment meter in functions; of the security functions; of the recording
response to the various inputs and outputs that are functions; of the metering function (optical test
presented at its interfaces. output for calibration) and of the system interfaces.
B-3.3 Token_Carrier_to_Meter_Interface Function B-3.9 Display Functions
The Token_Carrier_to_Meter_Interface function deals The generic Display function is a support function
with all activities related to the reading of information to all other functions embodied in the payment meter
from and also the writing of information to the and specific instances of display activities thus vary
Token_Carrier. It defines an application layer and according to the particular implementations.
physical layer in terms of the OSI reference model with
possible intermediate layers, while the token carrier is Examples of display devices are: alpha/numeric/
defined as the carrier medium in the physical layer. graphic LCD; LED indicator; neon indicator; visible
position of mechanical actuator lever; label on meter
B-3.4 Accounting Function panel and terminal cover; barcode under meter serial
The Accounting function maintains a current balance number; printed numeric codes on paper token carriers.
of all credit and charge transactions performed in Events to initiate or terminate the display process
the payment meter. These activities together may be manually generated by a user, such as: the
constitute the meter accounting process. press of a button; entering a code; inserting a special
B-3.5 Meter ing Function action token. Events may also be automatically
generated, such as a process state generating an
The Metering function primarily deals with the indication of an alarm condition.
measurement of the quantity of delivered electrical
energy to the consumer. These measurements are Examples of process indicators are: the acceptance
made available for use by other functions in the of a token; the rejection of a token; when a token is
payment meter. old (or expired); when a token has already been used;
after a successful completion of a key change
B-3.6 Deliver y Function operation; Examples of typical displayed information
The Delivery function primarily deals with the are: available credit; low level warning; accumulated
functions related to the delivery of electrical energy consumption; accumulated charges; tariff rate;
to the consumer’s load circuit. It also monitors the measured power; consumption rate; status of
status of the attributes of other functions, in incoming supply; state of the load switch; tamper
response to which it interrupts or restores the supply status; meter serial number; terminal cover markings;
of power. printed numeric token carrier; and alarm indication.

B-3.7 Time Functions B-3.10 Recor ding Functions

The Time function maintains date and time The generic Recording function is a support function
information and time reference information for use to all other functions embodied in the payment meter
by other functions. It also maintains status of any and specific instances of recording activities thus
backup supply used for time keeping during power vary according to the particular implementations. In
outage of the supply network. general, the Recording functions deal with recording
of data into memory registers in the payment meter
B-3.8 Test Functions and are initiated by the entering of tokens and the
occurrence of events within the meter application
The generic Test function is a support function to all process (such as metering pulses due to
other functions embodied in the payment meter and consumption). It would also deal with the recording
specific instances of tests thus vary according to of data onto the token carrier where this is
the particular implementations. implemented and as such it would be a support
Tests on a payment meter are typically initiated function to the Token_Carrier_to_Meter_Interface
manually by the action of a user (consumer, service function.
technician, installer, inspector). For example: the Examples of recording devices are: mechanical rotary
press of a button; entering a code; or inserting a registers; electronic memory in the payment meter or
special action token. on the token carrier; printing on labels on the
Examples of test functions are: testing for the correct payment meter user interface.

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IS 15884 : 2010

Examples of recording registers are: cumulative token Examples of recorded events are: credit expired;
credit register; cumulative social credit register; power limit exceeded; load switch opened/closed;
cumulative credit advance register; cumulative over/under voltage detected; phase unbalance
emergency credit register; cumulative lifeline credit detected; tamper detected; internal reset occurred;
register; cumulative total consumption register; tariff memory failure detected; and token entered.
rate registers, auxiliary charge rate registers; token
identifier register; date and time register; and load B-3.11 Secur ity Functions
switch activation count register. The generic Security function is a support function
Examples of recorded parameters are: daylight to all other functions embodied in the payment meter
savings; events calendar; power limit; under voltage and specific instances of security activities thus vary
limit; over voltage limit; phase unbalance limit; low according to the particular implementations.
credit warning level; accounting mode; emergency credit In general, the Security functions deal with
level; credit advance level; credit cycle; billing cycle; prevention and detection of physical access to sealed
activation date; expiry date; schedules of tariff rates; parts of the payment meter, assuring the integrity of
schedules of auxiliary charge rates; token identifier; recorded data elements and prevention of fraud in
cryptographic key; meter serial number; software the form of tampering with data elements. The latter
version; date of manufacture; manufacturer identifier. functions are present mainly in the application layer

FIG. 2 FUNCTIONAL BLOCK DIAGRAM OF A SINGLE-PART PAYMENT METER INSTALLATION

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protocol of the Token_Carrier_to_Meter_Interface Examples of data and function integrity methods are:
function. use of CRC and parity checks with blocks of data
elements; traceability of metrological certification.
Examples of physical protection and access control
devices are: metal seals crimped around steel sealing Examples of data tampering prevention are:
wires; one-way screws; breakout plastic sealing caps encryption/decryption techniques; message
for screw heads; tamper detection switch under sequencing; unique token identifiers; use of MAC
cover plate of meter and terminal block; conformal with data element blocks; use of public/private key
coating of electronic components; shielding against signatures on data blocks and messages; token
magnetic fields; preventing entry of foreign objects; validation; token cancellation; token authentication;
fail-safe techniques in the design of components (like token erasure; key expiry; and tariff expiry.
the load switch).

ANNEX C
(Clause 4.3.4)
RELATIONSHIP BETWEEN AMBIENT AIR TEMPERATURE AND RELATIVE HUMIDITY
(Normative)

FIG. 3 RELATIONSHIP BETWEEN AMBIENT AIR TEMPERATURE AND RELATIVE HUMIDITY

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IS 15884 : 2010

ANNEX D
(Clauses 4.3.1, 4.3.2(a) and (b), 4.4 and 5.1.7)
REQUIREMENTS OF TIME-KEEPING
(Normative)

D-1 GENERAL accuracy with temperature shall be less than 0.15 s/

°C/24 h.
D-1.1 Gener al
The crystal-controlled clock shall operate correctly
Where a payment meter is of a type that provides for for all values of frequency between 0.98 and 1.02
energy-based tariffs controlled from an internal real- times the rated supply frequency.
time clock, then the time-keeping requirements of this
Annex shall apply, at least as design requirements. On operation reserve, at reference temperature, the
The type-testing requirements in this Annex shall accuracy shall be better than 0.5 s/24 h, and the
not be mandatory where testing the time-keeping of variation of time-keeping accuracy with temperature
any internal real-time clock is not required for the shall be less than 0.15 s/°C/24 h.
legal metrology approval testing of payment meters.
NOTE — In applications where the payment meter is
NOTES used as part of a system providing overall time
synchronization, the manufacturer and the purchaser may
1 The calendar functions of any internal real-time clock
agree on relaxed time-keeping accuracy specifications for
are covered in A-2.4.2.
the payment meter when it is operating in stand-alone
2 Some tariff or security applications that are not related mode. In this case, the payment meter maintains the
to real time may employ an elapsed-time clock, but such system time and synchronization is performed by the
applications are not covered in this standard. system at the necessary intervals.
D-1.2 Real-Time Clock Suppor t Facilities D-3 TESTS OF TIME-KEEPING ACCURACY
Where a real-time clock is fitted and a battery or other D-3.1 Gener al Test Conditions
support device is used to provide an operation
reserve while no supply is available, then the Where the payment meter under test includes a clock
following requirements shall be met. During an it shall be placed in its normal operating position
interruption of the supply voltage not exceeding the and in a climatic chamber where required, and
operation reserve, the payment meter shall keep the supplied from a power source free of voltage dips
time within the prescribed accuracy. and short interruptions. Unless otherwise indicated,
the reference conditions shown in Table 11 shall be
An operation reserve shall be provided where the maintained.
clock is used for internal tariff control or control of
time-dependent credit. NOTE — For accuracy testing, the payment meter shall
be able to display the real time including the seconds, and
In cases where a real-time clock is fitted but an shall allow for a means of time synchronization where
operation reserve is either not fitted, or is not the seconds are either reset to zero, or to the intended
value. The manufacturer should also provide a suitable
available when the supply voltage is restored, the means on the payment meter for rapid testing of the
manufacturer shall state what default status and time-keeping accuracy. This could be, for example, an
indications are then adopted. electrical or optical output, or, in the case of capacitor-
calibrated crystal-controlled clocks, an electromagnetic
D-1.3 Real-Time Clock Setting Facilities coupling picking up the signal from the crystal. Where
such test facilities provide for the time-keeping accuracy
It shall be possible to set the date and time (day, to be assessed over a shorter period of time, then the
month, year, hours and minutes) with an accuracy of minimum period of time required for each test is that
stated below.
5 s. The setting of the time shall reset the seconds to
zero. If setting of the seconds is also available, then D-3.2 Test of Cr ystal-Controlled Clocks in Payment
the setting of the time shall not reset the seconds to Meter s
zero, but to the intended value. If a daylight saving
time function is available, the payment meter shall D-3.2.1 Test of Crystal-Controlled Clocks on ac
be capable of displaying the official time according Supplies
to the regulations. The payment meter under test is supplied with power
D-2 CRYSTAL-CONTROLLED CLOCKS and synchronized with a crystal controlled reference
clock. After a testing period of 2 days, the time-
Where fitted, a crystal-controlled time clock shall indication discrepancy between the reference clock
have time-keeping accuracy better than 0.5 s/24 h at and the payment meter under test shall not be more
reference temperature. The variation of time-keeping than 1 s. The minimum period of time for this test is 48 h.

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 IS 15884 : 2010

D-3.2.2 Test of Cr ysta l-Contr olled Clocks on indication discrepancy. According to 5.5.3, Test of
Operation Reserve immunity to radiated RF electromagnetic fields at 10
V/m, during the test the disturbances shall not
The payment meter to be tested is supplied with produce any change in the time displayed, and after
power and synchronized with a crystal controlled the test there must be no change in time indication
reference clock. Before the test, the payment meter discrepancy. According to 5.5.3, Test of immunity
shall be powered for a suitable length of time, so to radiated RF electromagnetic fields at 30 V/m, during
that the operation reserve is fully available. the test the disturbances may result in unavailability
NOTE — The manufacturer should specify the time of the setting facilities and a temporary change in
necessary for keeping the payment meter powered up timekeeping accuracy. However, after the test the time
before the test of operation reserve may commence. must be preserved. According to 5.5.4, Test of
immunity to electrical fast transients/bursts, during
The power supply to the payment meter under test is
the test the disturbances may result in unavailability
switched off for 36 h. When the power supply is
of the setting facilities and a temporary change in
restored, the time-indication discrepancy between
timekeeping accuracy. However, after the test the time
the reference clock and payment meter under test indication discrepancy must be preserved. According
shall not be more than ±1.5 s. The minimum time for to 5.5.5, Test of immunity to conducted disturbances,
this test is 36 h. The restoration of the voltage shall induced by RF fields, during the test the disturbances
be made with a switching device free from bounce. shall not produce any change in the time displayed,
D-3.2.3 Test of Accur a cy of Crysta l-Controlled and after the test there shall be no change in time
Clocks with Temperature indication discrepancy. According to 5.5.6, Surge
immunity test, during the test the disturbances shall
The payment meter is placed in a climatic chamber not produce any change in the time displayed,
and its time base is measured at +23°C. The however the disturbances may result in a blinking
temperature is then set at +45°C. After thermal display, unavailability of the setting facilities, and a
equilibrium is obtained, the time-keeping accuracy temporary change in timekeeping accuracy. After the
shall be better than ±3.3 s/ 24 h plus the time-keeping test the time indication discrepancy shall be preserved.
accuracy measured at reference temperature (Max ± NOTE — Where a payment meter includes provision for
0.5 s/ 24 h). alternative time-keeping facilities (that is either
synchronous or crystal-controlled modes may be selected
The accuracy of the time base shall not differ from for use), then the payment meter shall be tested in each
the 23°C measurement by more than ±38 × 10–6. of these modes.

The temperature is then set at –10°C. After thermal D-4.2 Voltage Dips and Shor t Inter r uptions
equilibrium is obtained the time-keeping accuracy D-4.2.1 General
shall be better than ±4.5 s/24 h plus the time-keeping
accuracy measured at reference temperature (Max ± The payment meter shall be designed in such a way
0.5 s/24 h). that voltage dips and short interruptions, including
those specified in 5.4.2 and in D-4.2.2 to D-4.2.4, do
The accuracy of the time base shall not differ from not adversely affect the timekeeping of any
the 23°C measurement by more than ±57 × 10–6. incorporated time function. Any internal timekeeping
No minimum period of time is stated for this test. facility shall not be affected adversely during these
tests and shall not exhibit any resulting time-
D-4 EFFECTS OF DISTURBANCES ON TIME- indication discrepancies of more than the amounts
KEEPING given below.
D-4.1 Electr omagnetic Distur bances D-4.2.2 Test of the Effects of Short Interruptions and
Voltage Dips
The payment meter shall be designed in such a way
that the electromagnetic disturbances specified For these tests, the payment meter is supplied in
in 4.5 and its sub-clauses do not have an adverse parallel with and synchronized to a suitable type of
permanent effect on the timekeeping of any reference clock before each test. Suitable equipment
incorporated time function, including where the meter is inserted in the power supply line to the payment
remains in powered operation after the disturbances meter in order to submit the payment meter under
have been removed. Any internal timekeeping facility test to programmable short interruptions and voltage
shall continue to operate during each of the EMC dips without any switching bounce.
tests in 5.5.2 to 5.5.6, without any temporary loss of D-4.2.3 Effect of Short Interruptions on Crystal-
function. According to 5.5.2, Test of immunity to Controlled Clocks
electrostatic discharges, during and after the test the
disturbances shall not produce any change in time The payment meter under test is submitted to the

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IS 15884 : 2010

same sequences of supply interruptions as described and the crystal-controlled reference clock shall not be
in D-4.2.3 above. After each test, the time-indication more than 1 s.
discrepancy between the payment meter under test
and the crystal-controlled reference clock shall not D-4.3 Har monics in the Voltage Wavefor m
be more than 1s in each case. The payment meter is supplied together with, and
D-4.2.4 Effect of Volta ge Dips on Cr ysta l- synchronized to, a suitable reference clock. A third
Controlled Clocks harmonic content equivalent to 10 % of Vref is added
to the supply voltage of the payment meter under
The payment meter under test is submitted to test, symmetrically to each phase in the case of a
sequences of 20 successive supply interruptions polyphase meter. The test is carried out for a period of
with at least 5 s intervals between each interruption. 48 h under reference conditions. At the end of the test,
The period of the interruptions to be applied shall the time-indication discrepancy between the payment
be100 ms in the first sequence and 1 s in the second meter under test and the reference clock shall not be
sequence. After the test the time indication more than ±1 s for synchronous clocks and not more
discrepancy between the payment meter under test than ±1 s for crystal controlled clocks.

ANNEX E
(Clauses 5.1.2, 5.1.4, 5.1.6 and 5.1.7)
RECOMMENDED TEST SEQUENCES
Table 20 Schedule of Type Tests
Sl No. Test Clause Refer ence Accep t a n ce R ou t in e
Test (A) Test (R)

(1) (2) (3) (4) (5)

i) Test s of I n su la t ion P r op er t ies 5.4.6 — —

ii) Impulse voltage test 5.4.6.2 — —
iii) ac voltage test 5.4.6.3 A R
iv) Insulation resistance test 5.4.6.4 A R
v) Test s of Accu r a cy Req u ir em en ts 5.6 — —
vi) Test on limits of error due to variation of the current 4.6.1 — R
vii) Test of meter constant 5.6.5 A —
viii) Test of starting condition 5.6.4 A R
ix) Test of no-load condition 5.6.3 A R
x) Test of repeatability of error 5.6.7 A —
xi) Test on limits of error due to other influence quantities 4.6.2 — —
xii) Test s of E lect r ica l R eq u ir em en t s 5.4 — —
xiii) Test of power consumption 5.4.1 A —
xiv) Test of influence of supply voltage 4.4.2 and 5.4.2 — —
xv) Test of influence of short-time over current 5.4.3 — —
xvi) Test of influence of self-heating 5.4.4 — —
xvii) Test of influence of heating 5.4.5 — —
xviii) Tests for Electr om agn etic Com p atib ility (EM C) 5.5 — —
xix) Radio interference measurement 5.5.5 — —
xx) Fast transient burst test 5.5.4 — —
xxi) Test of immunity to electromagnetic HF fields 5.5.3 — —
xxii) Test of immunity to electrostatic discharges 5.5.2 — —
xxiii) Surge Immunity test 5.5.6 — —
xxiv) Test s of C lim a t ic I n flu en ces 5.3 — —
xxv) Dry heat test 5.3.1 — —
xxvi) Cold test 5.3.2 — —
xxvii) Damp heat, cyclic test 5.3.3 — —
xxviii) Test of M ech a n ica l R eq u ir em en t s 5.2 — —
xxix) Vibration test 5.2.3 — —
xxx) Shock test 5.2.2 — —
xxxi) Spring hammer test 5.2.1 — —
xxxii) Tests of protection against penetration of dust and water 5.2.5 — —
xxxiii) Test of resistance to heat and fire 5.2.4 — —

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 IS 15884 : 2010

ANNEX F
(Clauses 4.2.10.8 and 4.2.10.9)
OPTICAL TEST OUTPUT
(Normative)

FIG. 4 TEST ARRANGEMENT FOR THE TEST OUTPUT

Requirements
tON > 0.2 ms
tOFF > 0.2 ms
tT < 20 us

F IG . 5 W AVE F ORM OF THE O PTICAL T EST O UTPUT

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IS 15884 : 2010

ANNEX G
(Clauses 3.12.6, 4.6.2.2 and 5.1.7)
PERFORMANCE REQUIREMENTS FOR PAYMENT METERS WITH LOAD SWITCHING
UTILIZATION CATEGORIES UC2 AND UC3
(Normative)

G-1 LOAD SWITCHING CAPABILITIES available credit is replenished, but only under manual
control; that is, by pushing a button or by manually
Payment meters with load switching category UC2 entering a token.
and UC3 shall have the following properties:
If the payment meter is programmed with other
a) Capable of making and breaking negligible functions that also operate the load switch, then
currents of specified values; these other functions shall be disabled for the
b) Capable of making, breaking and carrying rated purpose of this test. The test is carried out under the
currents of specified values; following conditions:
c) Capable of making into fault currents with
a) Payment meter in normal operating
specified value and under specified
condition;
conditions;
b) Load a small amount of available credit, so
d) Capable of carrying short-circuit currents of
that the load switch restores the supply to
specified value for a specified time period and
the load circuit;
under specified conditions;
c) Supply voltage at, or just above, the lowest
e) Not required to provide safety isolation
value of the rated operating voltage range;
properties in the open contact position. These
are requirements for the installation mains d) Current in the load circuit at Ic and PF = 1.0.
isolation switch; and Wait until the available credit expires and check for
f) Not required to break overload currents or compliance with the following requirements:
short-circuit currents. These are requirements
for fuses and circuit breakers that are normally a) The load switch shall interrupt the supply
used to protect the installation. to the load circuit;
b) The load switch shall operate on the first
A summary of test currents for utilization categories attempt;
UC2 and UC3 is given in Table 21.
c) There shall be no evidence of sticking of
Table 21 Summar y of Test Cur r ents the contacts;
for UC2 and UC3 d) There shall be no change in any of the
Test Clause UC 2 UC 3 memory registers in the payment meter,
except for those that are expected to change;
(1) (2) (3)
and
Fault current making capacity (see G -5) 2.5 3
KA KA
e) Repeat the test 3 times.
Short-circuit current carrying 4.5 6 Where a load switch has a mechanical actuating lever
capacity test 1 (see G -6) KA KA
for manually closing or opening the contacts, then
Short-circuit current carrying 2.5 3 perform each test when the lever is held in the
capacity test 2 (see G -6) KA KA
following positions:
NOTE — Where the payment meter load switching capability
is also used as part of the main circuit protection or isolation a) When pushing the lever in the direction for
at the customer’s premises, then such additional requirements closing of the contacts, then hold the lever
may be specified through reference to other specifications or at the nearest point where the load switch
standards.
contacts have just made contact;
G-2 NORMAL OPERATION
b) By inspection, select the nearest point to
The load switch shall be operable by the payment where the contacts are placed under the
meter to interrupt the supply to the load circuit when greatest pressure during the closing
available credit expires. operation; and

The load switch shall be operable by the payment c) Where the lever is in its normal resting
meter to restore the supply to the load circuit when position after the contacts have closed.

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 IS 15884 : 2010

G-3 ELECTRICAL ENDURANCE are grouped and connected together; and all current
carrying phase and neutral output terminals are
The test shall be carried out on a new sample under grouped and connected together. All other terminals
the following conditions: are connected to a safety ground reference.
a) Payment meter in normal operating Perform the test in accordance with IEC 61000-4-5
condition; under the following conditions:
b) Room temperature at reference conditions;
a) With load switch contacts in open position;
c) 1 m length cable with current carrying
capacity of Ic; b) Payment meter in the non-operating mode;
d) Supply voltage at Vc; c) Between the group of input terminals and
the group of output terminals;
e) Load current at Ic and PF = 1.0; and
d) Ambient temperature at reference
f) Number of operating cycles equal to 5 000,
conditions;
with 10 s make time and 20 s break time.
e) Relative humidity at 40 percent to 60 percent;
Repeat the test using the same sample, but with the
following changes: f) Atmospheric pressure at 80 kPa to 106 kPa;
Load current at Ic, and PF = 0.5 inductive. g) Cable length between surge generator and
payment meter at 1 m;
During and after the test the following requirements h) Open circuit voltage of generator at 6 kV
shall be met: (1.2/50 μs);
a) The load switch shall show no signs of j) Prospective short-circuit current of 250 A
malfunction, sticking of contacts or peak;
reluctance to latch; k) Generator source impedance of 24 Ohm;
b) The contacts shall open on the first attempt; m) 5 positive and 5 negative impulses; and
c) After the test it shall meet the requirements n) Repetition rate not faster than 1 impulse per
of G-7: test for minimum switched current; minute.
d) After the test it shall meet the requirements
of 4.4.1 and its sub-clauses: test for power During and after the test the following requirements
consumption; shall be met:
e) After the test it shall meet the requirements a) It is permitted for flashover and disruptive
of G -8: test for dielectric strength; and discharge to occur during the test;
f) When the payment meter is returned to b) There shall be no permanent damage to any
normal operating conditions, it shall operate part of the payment meter; and
correctly and there shall be no change in c) When the payment meter is returned to
any of the memory registers, except for those normal operating conditions, it shall operate
that are expected to change. correctly and there shall be no change in
NOTES any of the memory registers.
1 One operating cycle of the load switch is one make NOTES
followed by one break action.
1 In certain networks lightning arrestors are only fitted
2 For the purpose of this test, the payment meter differentially between the live and neutral lines.
manufacturer may provide an external means, which Lightning conditions are thus able to induce common
allows for the opening and closing of the load switch to mode voltage impulses in such a network on the live
be under the control of the test equipment. and neutral lines relative to earth. If the load switch
contacts are in the open position under such conditions,
G-4 LINE TO LOAD VOLTAGE SURGE then the impulse voltage will attempt to find a discharge
WITHSTAND path though any circuit that is connected across the
open contacts to the load-side circuit, thus possibly
The payment meter shall be able to withstand causing damage to internal circuitry of the payment
simulated lightning induced common mode voltage meter.
surges as might be expected in a typical domestic 2 This test is specifically designed for the case where
installation, while the load switch contacts are in the there is internal electrical coupling of circuits between
the input and output terminals of the payment meter
open position. when the load switch contacts are in the open condition.
The test is only applicable to a payment meter in G-5 FAULT CURRENT MAKING CAPACITY
which the neutral line is also switched.
The payment meter shall be capable of making into
All current carrying phase and neutral input terminals simulated fault currents as given in this clause.

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IS 15884 : 2010

Perform the test on a new payment meter sample NOTES

under the following conditions: 1 One pre-fusing operating cycle is to maintain the
switch contacts in the closed condition for 5 s, then to
a) Climatic conditions at reference values; maintain the switch contacts in the open condition for 5 s.
b) Payment meter in the normal operating 2 One operating cycle of the load switch is one make
condition; followed by one break action.

c) Voltage source at Vc; 3 Standard r.m.s. current breaking capacity values for
residual current devices are 3 kA, 4.5 kA, 6 kA, 10 kA
d) 3 pre-fusing operating cycles at I c and and 20 kA, which represent the fault current levels
PF = 1.0 at 10 s intervals; that the load switch of a payment meter is expected to
make. The first value is chosen for utilisation categories
e) Prospective test current at 2.5 kA r.m.s. for UC3 as representing the short-circuit current sourcing
utilization category UC2; capacities at the load connection socket outlet points
of wired premises where payment meters are commonly
f) Prospective test current at 3 kA r.m.s. for installed. Further categories may be created in future
utilization category UC3; for higher current values. The values given for UC2
g) Power factor of test current shall be 0.85 and correspond to a special category, applicable only to
certain countries where large quantities of prepayment
0.90 inductive; meters are installed, which are rated to these levels of
h) Frequency at reference value; fault current withstand.
+5 4 The aim of the test is to check for welding of contacts
j) Current tolerance í 0
percent; caused by contact bounce at the point of closure into

k) Voltage tolerance ±5 percent; and the test current. The let-through energy is not an
essential part of this evaluation at present and is thus
m) Power factor tolerance percent. constrained to a value that amounts to less than would
be expected from protection devices of either a fuse
Cause the payment meter to close the load switch type or circuit breaker type normally used in the
distribution board of the wired premises under short-
contacts into the above prospective test current and circuit conditions.
to remain in the closed position. 5 The values of overload currents under consideration
are multiples of 3, 5, 10, 20 and 30 of Ic at PF = 0.8 and
The test current shall be maintained to flow up to the shall be co-ordinated with the maximum time delays
first zero point crossing of the current, at which point, expected from network protection devices at these
the test equipment shall disconnect the voltage current values.
source. 6 It is recommended that the plotted graph of the
voltage and test current waveform be attached to the
Repeat the test 3 times on the same sample with a test report for future reference.
minimum delay of 1 min between each test. 7 It is not permitted to allow the load switch to be
activated under the control of the external test
Plot a graph of the voltage and the test current equipment, because it could possibly negate special
waveform during each test and verify that the test techniques that the payment meter application process
may employ, such as zero point switching. The load
was executed as is required.
switch contacts thus have to be caused to close under
During and after the test the following requirements the direct control of the payment meter itself.
shall be met: G-6 SHORT-CIRCUIT CURRENT CARRYING
a) Contacts shall open on the first attempt after CAPACITY
each make cycle; The payment meter shall withstand simulated short-
b) The load switch shall show no signs of circuit currents as may be experienced under short-
malfunction, sticking or welding of contacts circuit conditions in a payment meter installation.
or reluctance to latch;
Test 1 shall be carried out on a new payment meter
c) After the test it shall meet the requirements
sample under the following conditions:
of G-7: test for minimum switched current;
d) After the test it shall meet the requirements a) Climatic conditions at reference values;
of 4.4.1 and its sub-clauses: test for power b) Series connection of a voltage source, the
consumption; payment meter under test, load to produce
e) After the test it shall meet the requirements the required test current and a test switch;
of G-8: test for dielectric strength; and c) Payment meter in the normal operating
f) When the payment meter is returned to condition;
normal operating conditions, it shall operate d) 3 pre-fusing operating cycles at I c and
correctly and there shall be no change in PF =1.0 at 10 s intervals;
any of the memory registers, except for those e) Load switch contacts in the closed position;
that are expected to change.
48