En 50470-3 2006
En 50470-3 2006
En 50470-3 2006
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2006
ICS 91.140.50
English version
This European Standard was approved by CENELEC on 2006-05-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Foreword
This European Standard was prepared by the Technical Committee CENELEC TC 13, Equipment for
electrical energy measurement and load control.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by
CENELEC as EN 50470-3 on 2006-05-01.
The structure of the standards is similar, modifications in this Euroepan Standard are provided in the
perspective of compliance with the Essential Requirements of the Directive 2004/22/EC on Measuring
Instruments (MID).
This standard is to be used with EN 50470-1:2006, Electricity metering equipment (a.c.) – Part 1:
General requirements, tests and test conditions – Metering equipment (class indexes A, B and C).
This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and covers essential requirements of
EC Directive 2004/22/EC. See Annex ZZ.
__________
–3– EN 50470-3:2006
Contents
1 Scope ...............................................................................................................................5
2 Normative references .......................................................................................................5
3 Terms, definitions and abbreviations ................................................................................5
4 Standard electrical values ................................................................................................6
5 Mechanical requirements ..................................................................................................6
6 Climatic conditions ...........................................................................................................6
7 Electrical requirements .....................................................................................................6
7.1 Power consumption .................................................................................................6
7.1.1 Measurement method ..................................................................................6
7.1.2 Voltage circuits ............................................................................................6
7.1.3 Current circuits ............................................................................................6
7.2 AC voltage test........................................................................................................7
8 Accuracy requirements and tests ......................................................................................7
8.1 Limits of percentage error due to variation of the load .............................................7
8.2 Repeatability ...........................................................................................................8
8.3 Limits of additional percentage error due to influence quantities ..............................8
8.4 Maximum permissible error (MPE) ......................................................................... 10
8.5 Effect of disturbances of long duration................................................................... 10
8.6 Short time overcurrents ......................................................................................... 12
8.7 Performing the tests .............................................................................................. 12
8.7.1 Accuracy test conditions ............................................................................ 12
8.7.2 Accuracy tests at reference conditions ...................................................... 13
8.7.3 Interpretation of accuracy test results ........................................................ 14
8.7.4 Repeatability ............................................................................................. 14
8.7.5 Test of effects of influence quantities......................................................... 14
8.7.6 Calculation of the composite error ............................................................. 15
8.7.7 Test of effects of disturbances of long duration.......................................... 15
8.7.8 Short time overcurrents ............................................................................. 18
8.7.9 Test of starting and no-load condition ........................................................ 19
8.7.10 Meter constant........................................................................................... 20
9 Durability ........................................................................................................................ 20
10 Reliability ....................................................................................................................... 20
11 Requirements concerning the software and protection against corruption ....................... 21
11.1General ................................................................................................................. 21
11.2Identification of functions implemented in software ................................................ 21
11.3Identification and protection of software ................................................................ 21
11.4Identification and protection of metrologically relevant parameters ........................ 21
11.5Setting of parameters ............................................................................................ 22
11.6Protection of measurement data ............................................................................ 22
11.7Protection against inadmissible influence by metrologically non-relevant
software ................................................................................................................ 22
11.8 Protection against inadmissible influence by connecting another device ................ 22
Annex A (informative) Calculation of the composite error ..................................................... 23
Annex B (normative) Test circuit diagram for the test of immunity to earth fault ................... 24
EN 50470-3:2006 –4–
Annex C (normative) Test circuit diagram for d.c., even harmonics, odd harmonics and
sub-harmonics ................................................................................................................ 25
Annex ZZ (informative) Coverage of Essential Requirements of EC Directives ..................... 30
Bibliography.......................................................................................................................... 31
Figures
Tables
1 Scope
This European Standard applies to newly manufactured static watt-hour meters intended for
residential, commercial and light industrial use, of class indexes A, B and C, for the measurement of
alternating current electrical active energy in 50 Hz networks. It specifies particular requirements and
type test methods.
It applies to static watt-hour meters for indoor and outdoor application, consisting of a measuring
element and register(s) enclosed together in a meter case. It also applies to operation indicator(s) and
test output(s).
If the meter has (a) measuring element(s) for more than one type of energy (multi-energy meters), or
when other functional elements, like maximum demand indicators, electronic tariff registers, time
switches, ripple control receivers, data communication interfaces etc. are enclosed in the meter case
(multi-function meters) then this standard applies only for the active energy metering part.
– watt-hour meters where the voltage across the connection terminals exceeds 600 V (line-to-
line voltage for meters for polyphase systems);
– portable meters;
– reference meters.
1)
Methods for acceptance testing are covered by the IEC 62058 series of standards .
The dependability aspect is covered by the documents of the IEC 62059 series.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 50470-1 2006 Electricity metering equipment (a.c.) – Part 1: General requirements, tests
and test conditions – Metering equipment (class indexes A, B and C)
———————
1)
At draft stage.
EN 50470-3:2006 –6–
5 Mechanical requirements
6 Climatic conditions
7 Electrical requirements
In addition to the electrical requirements in EN 50470-1, meters shall fulfil the following requirements.
The power consumption in the voltage and current circuits shall be determined at reference conditions
given in 8.7.1 by any suitable method. The overall maximum error of the measurement of the power
consumption shall not exceed 5 %.
The active and apparent power loss in each voltage circuit of a meter at reference voltage, reference
temperature and reference frequency shall not exceed the values shown in Table 1.
The apparent power taken by each current circuit of a meter at reference current, reference frequency
and reference temperature shall not exceed the values shown in Table 2.
–7– EN 50470-3:2006
The a.c. voltage test shall be carried out in accordance with Table 3.
The test voltage shall be substantially sinusoidal, having a frequency between 45 Hz and 65 Hz, and
applied for 1 min. The power source shall be capable of supplying at least 500 VA.
For the tests relative to earth, the auxiliary circuits with reference voltage equal to or below 40 V shall
be connected to earth.
All tests shall be carried out with the case closed and the cover and terminal cover(s) in place.
When the meter is under reference conditions given in 8.7.1, and the current and the power factor are
varied, the percentage errors shall not exceed the limits specified for the relevant class indexes in
Table 4 and Table 5.
If the meter is designed for the measurement of energy in both directions, the values in Table 4 and
Table 5 shall apply for each direction.
EN 50470-3:2006 –8–
The difference between the percentage error when the meter is carrying a single-phase load and a
balanced polyphase load at Iref and unity power factor shall not exceed 2,5 %, 1,5 % and 1 % for class
indexes A, B and C respectively.
8.2 Repeatability
The application of the same measurand under the same conditions of measurement shall result in the
close agreement of successive measurements. The repeatability at any test point given in Table 13
th
shall be better than 1/10 of the limit of percentage error at reference conditions. The manufacturer
shall state the necessary number of pulses.
When the current and the power factor are held constant at a point within their respective specified
measuring ranges, and any single influence quantity is taken from its reference value and varied within
its specified operating range, with the meter otherwise operated at reference conditions as specified in
8.7.1, the additional percentage error shall not exceed the limits specified for the relevant class
indexes given in Table 6 and Table 7.
Concerning additional percentage error due to temperature variation, the requirements for each sub-
range within the full temperature range specified by the manufacturer apply.
NOTE For example, if the manufacturer specifies that the meter is intended for the temperature range -10 °C to + 40 °C, then
the requirements for the sub-ranges 5 °C to 30 °C, -10 °C to 5 °C and 30 °C to 40 °C apply.
–9– EN 50470-3:2006
Temperature
variation
Imin ≤ I ≤ Imax 1 ± 1,8 ± 0,9 ± 0,5
5 °C to 30 °C
Itr ≤ I ≤ Imax 0,5 ind, 0,8 cap ± 2,7 ± 1,3 ± 0,9
-10 °C to 5 °C Imin ≤ I ≤ Imax 1 ± 3,3 ± 1,6 ± 1,0
Temperature
variation
1 ± 1,8 ± 0,9 ± 0,5
5 °C to 30 °C Itr ≤ I ≤ Imax
0,5 ind ± 2,7 ± 1,3 ± 0,9
-10 °C to 5 °C 1 ± 3,3 ± 1,6 ± 1,0
Itr ≤ I ≤ Imax
30 °C to 40 °C 0,5 ind ± 4,9 ± 2,3 ± 1,6
In addition to the requirements of 8.1 and 8.3, the composite error of the meter shall not exceed the
values given in Table 8.
When the operating range of the meter covers more than one temperature range, then the respective
requirements for each temperature range apply.
The composite error at a certain load shall be calculated from the following formula:
where
δ (T , I , cos ϕ ) = the additional percentage error due to the variation of the temperature at
the same load;
δ (U , I , cos ϕ ) = the additional percentage error due to the variation of the voltage at the
same load;
δ ( f , I , cos ϕ ) = the additional percentage error due to the variation of the frequency at the
same load.
When the meter is otherwise operated at reference conditions, the additional percentage error due to
disturbances of long duration, when applied one by one, shall not exceed the critical change values
specified in Table 9.
Value of current
Critical change value for
(balanced unless
meters of class index, %
otherwise stated)
Power
Disturbance Value For trans-
For direct factor
former
connected A B C
operated
meters
meters
0,8 Un ≤ U < 0,9 Un 1 ± 3,0 ± 2,1 ± 0,6
1,1 Un < U ≤
Severe voltage 1,15 Un 0,5 ind ± 4,5 ± 3,0 ± 1,2
10 Itr In
variation
1 and
U < 0,8 Un +10…–100
0,5 ind
Reversed phase Any two phases
Itr 0,1 In 1 ± 1,5 ± 1,5 ± 0,3
sequence interchanged
One or two phases
Voltage unbalance 10 Itr In 1 ± 4,0 ± 2,0 ± 1,0
interrupted a
1 ± 1,0 ± 0,7 ± 0,2
Self-heating Imax Imax
0,5 ind ± 1,5 ± 1,0 ± 0,2
Earth fault b 1,9 Un on two lines - 0,5 In 1 ± 1,0 ± 0,7 ± 0,3
Harmonic components 10 % U,
in the current and 40 % I 0,5 Imax 0,5 Imax 1 ± 1,0 ± 0,8 ± 0,5
voltage circuits 5th harmonic
DC and even
harmonics in the a.c. I max
- 1 ± 6,0 ± 3,0 ± 1,5
current circuit c 2
Odd harmonics in the
5 Itr 0,5 In 1 ± 6,0 ± 3,0 ± 1,5
a.c. current circuit
Sub-harmonics in the
5 Itr 0,5 In 1 ± 6,0 ± 3,0 ± 1,5
a.c. current circuit
Continuous magnetic 1 000 Ampere-
10 Itr In 1 ± 3,0 ± 2,0 ± 1,0
fields of external origin turns
Power frequency
magnetic fields of 0,5 mT 10 Itr In 1 ± 3,0 ± 2,0 ± 1,0
external origin
Radiated RF
10 V/m 10 Itr In 1 ± 3,0 ± 2,0 ± 1,0
electromagnetic fields
Operation of auxiliary Most unfavourable
Imin Imin 1 ± 1,0 ± 0,5 ± 0,1
devices condition
Electrical fast
4 kV (2 kV) 10 Itr In 1 ± 6,0 ± 4,0 ± 2,0
transient/burst
Conducted
disturbances induced 10 V 10 Itr In 1 ± 3,0 ± 2,0 ± 1,0
by RF fields
Damped oscillatory
2,5 kV / 1 kV - In 1 ± 3,0 ± 2,0 ± 1,0
waves d
a 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 phases are interrupted.
– in a three-phase, four wire network one or two phases ;
– in a three-phase, three-wire network (if the meter is designed for this service) one of the three phases.
This only covers phase interruptions and does not cover events such as transformer fuse failures.
In case of polyphase meters with two measuring elements the test does not apply.
b Only for three-phase four-wire voltage transformer operated meters connected to distribution network equipped with earth fault
neutralizers.
c This requirement does not apply to current transformer operated meters.
d For voltage transformer operated meters only.
EN 50470-3:2006 – 12 –
Short-time overcurrents shall not damage the meter. The meter shall perform correctly when back to
its initial working condition and the additional error shall not exceed the critical change value specified
in Table 10.
NOTE This requirement does not apply to meters having a contact in the current circuits. For this case, see the appropriate
standards.
To test the accuracy requirements, the following test conditions shall be maintained:
a) the meter shall be tested in its case with the cover in position; all parts intended to be earthed
shall be earthed;
b) before any test is made, the circuits shall have been energized for a time sufficient to reach
thermal stability;
– the voltages and currents shall be substantially balanced (see Table 11).
Condition Tolerance
Each of the voltages between phase and neutral and between any two ±1%
phases shall not differ from the average corresponding voltage by more than
Each of the currents in the conductors shall not differ from the average ±2%
current by more than
The phase displacements of each of these currents from the corresponding 2°
phase-to-neutral voltage, irrespective of the phase angle, shall not differ from
each other by more than
The accuracy test at reference conditions shall be performed at least at the test points shown in
Table 13 and it shall be verified that the requirements of 8.1 are met.
In case of polyphase meters, tests shall be performed with balanced three-phase voltage and with
balanced three-phase or single-phase load as indicated. For testing with single-phase load, the test
current shall be applied to each measuring element in sequence.
EN 50470-3:2006 – 14 –
Certain test results may fall outside the percentage limits indicated in Table 4 and Table 5, owing to
uncertainties involved in the measurement process. However, if by one displacement of the zero line
parallel to itself by no more than the limits indicated in Table 14, all the test results are brought within
the limits, it shall be considered that the requirements set in those tables are met.
8.7.4 Repeatability
To verify that the requirement of 8.2 is met, at each test point shown in Table 13 at least three
measurements shall be done.
8.7.5.1 General
The additional percentage error due to influence quantities shall be determined for each influence
quantity one by one, at the test points specified in Table 13, with all other influence quantities kept at
their reference values (see Table 12).
The additional percentage error due to temperature variation shall be determined for each sub-range
within the temperature range selected by the manufacturer.
NOTE If the variation of error is known to be a monotonic function of the temperature, it is sufficient to perform the test at the
extremes of each sub-range.
It shall be verified that the requirements of Table 6 and Table 7 for each relevant temperature range
are met.
– 15 – EN 50470-3:2006
The additional percentage error due to voltage variation shall be determined and it shall be verified
that the requirements of Table 6 and Table 7 are met.
If the meter has more than one reference voltage, the test shall be repeated for each value of Un.
NOTE If the variation of error is known to be a monotonic function of the voltage, it is satisfactory to perform the test at the
extremes of the voltage range(s).
The additional percentage error due to frequency variation shall be determined and it shall be verified
that the requirements of Table 6 and Table 7 are met.
NOTE If the variation of error is known to be a monotonic function of the frequency, it is satisfactory to perform the test at the
extremes of the frequency range.
The composite error shall be calculated using the formula given in 8.4. For each test point, the intrinsic
error and the largest corresponding values of additional percentage errors due to the variation of the
respective influence quantities within their specified operating range shall be taken into account.
8.7.7.1 General
The effect of disturbances of long duration shall be determined for each disturbance one by one, at the
test points shown in Table 9, while otherwise the meter is under reference conditions as specified in
8.7.1.
The additional percentage error due to severe voltage variation shall be determined and it shall be
verified that it does not exceed the critical change value specified in Table 9.
If the meter has more than one reference voltage, the test shall be repeated for each value of Un.
NOTE If the variation of error is known to be a monotonic function of the voltage, it is satisfactory to perform the test at the
extremes of the voltage range(s).
This requirement applies only for three-phase meters. The test shall be performed first interchanging
L1 and L2 then L1 and L3. It shall be verified that the additional percentage error does not exceed the
critical change value specified in Table 9.
This requirement applies only for poly-phase meters with three measuring elements.
The test shall be performed by interrupting each phase one by one or any two phases, as applicable.
It shall be verified that the additional percentage error does not exceed the critical change value
specified in Table 9.
EN 50470-3:2006 – 16 –
8.7.7.5 Self-heating
The test shall be carried out as follows: After the voltage circuits have been energized at reference
voltage for at least 1 h for meters of class index A and 2 h for class index B and C, without any current
in the current circuits, the maximum current shall be applied to the current circuits.
The percentage error of the meter shall be measured immediately after the current is applied and then
at intervals short enough to allow a correct drawing to be made of the curve of error variation as a
function of time. The test shall be carried out for at least 1 h, and in any event until the variation of
error during 20 min does not exceed 10 % of limits of percentage error at reference conditions. With
minimum interruptions for changing the measurement point, the percentage error of the meter shall be
measured at power factor = 1 and power factor = 0,5 inductive.
The cable to be used for energizing the meter shall have a length of 1 m and a cross-section to ensure
2 2
that the current density is between 3,2 A/mm and 4 A/mm . If this would result in a cable with a cross
2 2
section of less than 1,5 mm , then a cable with a cross section of 1,5 mm shall be used.
It shall be verified that the variation in percentage error does not exceed the critical change value
specified in Table 9.
This test applies only for three-phase four-wire voltage transformer operated meters, connected to
distribution networks which are equipped with earth fault neutralizers or in which the star point is
isolated (in the case of an earth fault and with 10 % overvoltage, the line-to-earth voltages of the two
lines which are not affected by the earth fault will rise to 1,9 times the nominal voltage).
For a test under a simulated earth fault condition in one of the three lines, all voltages are increased to
1,1 times the nominal voltages during 4 h. The neutral terminal of the meter under test is disconnected
from the ground terminal of the meter test equipment (MTE) and is connected to the MTE's line
terminal at which the earth fault has to be simulated (see Annex B). In this way the two voltage
terminals of the meter under test, which are not affected by the earth fault are connected to 1,9 times
the nominal phase voltages. For this test, the current circuits are set to 50 % of rated current In, power
factor 1 and symmetrical load. After the test, the meter shall show no damage and shall operate
correctly.
After the application of the simulated earth fault condition, the meter shall be allowed to return to the
initial temperature then an accuracy test shall be performed. It shall be verified that the variation in
percentage error does not exceed the critical change value specified in Table 9.
It shall be verified that additional percentage error does not exceed the critical change value specified
in Table 9.
8.7.7.8 Influence of d.c. and even harmonics in the a.c. current circuit
NOTE This test is applicable to direct connected meters only.
The tests of the influence of direct current and even harmonics shall be made with the circuit shown in
Figure C.1, or with other equipment able to generate the required waveforms, and the current
waveforms as shown in Figure C.2.
I max
The value of the current (before applying the distortion) shall be , at unity power factor.
2
The additional percentage error when the meter is subjected to the test waveform compared to the
percentage error when it is subjected to the reference waveform shall not exceed the critical change
value given in Table 9.
The tests of the influence of odd harmonics and sub-harmonics shall be made with the circuit shown in
Figure C.4 or with other equipment able to generate the required waveforms, and the current
waveforms as shown in Figure C.5 and Figure C.7 respectively.
The additional percentage error when the meter is subjected to the test waveform compared to the
percentage error when it is subjected to the reference waveform shall not exceed the critical change
value given in Table 9.
It shall be verified that the additional percentage error does not exceed the critical change value
specified in Table 9.
It shall be verified that the additional percentage error does not exceed the critical change value
specified in Table 9.
It shall be verified that the additional percentage error does not exceed the critical change value
specified in Table 9.
This test applies to meters with auxiliary devices enclosed in the meter case. Such devices may not be
operating or actuated continuously.
EN 50470-3:2006 – 18 –
It shall be verified that due to the operation or actuation of such auxiliary devices, the additional
percentage error does not exceed the critical change value specified in Table 9.
When such auxiliary devices are actuated by an external device, the auxiliary circuits shall preferably
be marked to indicate the correct method of its connection. If these connections are made by means
of plugs and sockets, they should be irreversible.
The test shall be performed with the connections specified by the manufacturer. In the absence of
such markings or irreversible connections, the test shall be performed with the connections giving the
most unfavourable condition.
It shall be verified that the additional percentage error does not exceed the critical change value
specified in Table 9.
It shall be verified that the additional percentage error does not exceed the critical change value
specified in Table 9.
It shall be verified that the additional percentage error does not exceed the critical change value
specified in Table 9.
The test circuit shall be practically non-inductive and the test shall be performed for polyphase meters
phase-by-phase.
The meter shall be able to carry a short-time overcurrent of 30 Imax with a relative tolerance of
+ 0 % to - 10 % for one half-cycle at rated frequency.
The meter shall be able to carry for 0,5 s a current equal to 20 Imax with a relative tolerance of
+ 0 % to - 10 %.
After the application of the short time overcurrent, the meter shall be allowed to return to the initial
temperature with the voltage circuit(s) energized (about 1 h) then an accuracy test shall be
performed. It shall be verified that the requirements of 8.6 are met.
– 19 – EN 50470-3:2006
For these tests, the conditions and the values of the influence quantities shall be as stated in 8.7.1
except for any changes specified below.
The meter shall be functional within 5 s after the rated voltage is applied to the meter terminals.
When the voltage is applied with no current flowing in the current circuit the test output of the meter
shall not produce more than one pulse.
For this test the current circuit shall be open circuit and a voltage of 115 % of the reference voltage
shall be applied to the voltage circuits.
240 ⋅ 10 3
∆t ≥ min
k ⋅ m ⋅ U test ⋅ I st
where
k is the number of pulses emitted by the output device of the meter per kilowatthour
(imp/kWh);
NOTE For transformer-operated meters with primary or half-primary registers, the constant k shall
correspond to the secondary values (voltage and currents).
Utest is the test voltage in volts; its value shall be 1,15 Un;
8.7.9.4 Starting
The meter shall start and continue to register at the starting current values (and in case of polyphase
meters, with balanced load) shown in Table 15.
If the meter is designed for the measurement of energy in both directions, then the fulfilment of this
requirement shall be verified with energy flowing in each direction.
The relation between the test output and the indication of the register shall comply with the marking on
the name-plate. The difference of the percentage error determined from the test output and by reading
th
the register shall be less than 1/10 of the limit of percentage error at reference conditions.
This shall be verified by measuring a sufficient amount of energy, and observing the test output and
reading the display.
9 Durability
The meter shall be designed to maintain an adequate stability of its metrological characteristics over a
period estimated by the manufacturer, provided that it is properly installed, maintained and used
according to the manufacturer’s instruction when in the environmental conditions for which it is
intended.
Conformity to this requirement shall be verified by the examination of test results and/or design
documentation provided by the manufacturer.
– laboratory test results of key parts and assemblies determining the long term stability of the meter
and/or of complete meters;
NOTE 2 The test method should be described by the manufacturer and should be based – as far as possible – on
internationally accepted standards and generally accepted methods.
– any specifications and calculations of the long term stability of such parts and assemblies;
– any operating principles used to maintain and improve long term stability;
– any manufacturing processes applied to ensure and improve long term stability;
– any methods to indicate if long term stability is affected.
10 Reliability
The meter shall be designed to operate reliably. It shall be designed to reduce as far as possible the
effects of any fault that would lead to an inaccurate measurement result, unless such a defect is
obvious.
Conformity to this requirement shall be verified by the examination of test results and/or design
documentation provided by the manufacturer.
– any methods applied to reduce the effect of eventual faults occurring on the accuracy of the
measurement and/or integrity of data;
NOTE 3 The effect of any faults may be reduced by applying redundant designs. However, this, due to higher number of
parts, may lead to higher unreliability. Therefore, the use of redundant designs should be left to the judgement of the
manufacturer.
– any method used to indicate if measurement accuracy is affected and/or integrity of data is lost.
11.1 General
In addition to the requirements of EN 50470-1, Subclause 5.2.1, the following requirements apply to
metering equipment, in which metrologically relevant functions are realised partly by software.
The functions implemented in software shall be unambiguously identified and their operation
adequately documented by the manufacturer.
NOTE Metrologically relevant functions implemented in software may include, but not limited to:
– the conditioning and processing of the input signals;
– compensation of the effect of influence quantities;
– the generation, storage and display of the measurement results;
– controlling the starting and running with no load;
– the setting and changing of metrologically relevant parameters;
– the control of operation indicator(s) and the test output(s);
– recovery from fault conditions;
– tariff control.
Software identification shall be easily provided. The manufacturer shall ensure that the version of
metrologically relevant software of the meter used in serial production is identical with the version
included in the type approval confirmation. The software shall be protected against any accidental or
intentional changes. Evidence of any intervention shall be available for a reasonable period of time.
NOTE If the software can only be changed after breaking (a) seal(s) or breaking the case, this is considered as an adequate
level of protection.
Furthermore, any corruption of the metrologically relevant software shall be easily detectable.
Metrologically relevant parameters shall be identified and protected against any accidental or
intentional changes after placing the legal metrology seals.
NOTE 1 Examples of such parameters are calibration constants, meter constant of the test output.
NOTE 2 If the metrologically relevant parameters can only be changed after breaking (a) seal(s) or breaking the case, this is
considered as an adequate level of protection.
Furthermore, any corruption of the metrologically relevant parameters shall be easily detectable.
EN 50470-3:2006 – 22 –
If there are parameters, which are allowed to be set in the field, this shall be possible only under
adequate protection, using the method specified by the manufacturer.
NOTE 1 Examples are transformer ratios or other data used for matching the meter to installation conditions.
Measurement data shall be protected against any accidental or intentional changes or corruption.
Evidence of any such events shall be readily available for a reasonable period of time.
The security system of the meter, providing protection of software, parameters and measurement data
– including any hardware and software solutions – shall be adequately documented.
If metrologically non-relevant functions implemented by software are present, these shall not
inadmissibly influence the correct operation of the metrologically relevant software.
Conformity to these requirements shall be verified by examining the software documentation and, as
applicable, using the test methods and tools provided by the manufacturer.
For an intermittent operation of metrologically not relevant software, the requirements of Table 9 for
the operation of auxiliary devices also apply.
The metrological characteristics of the meter shall not be influenced in any inadmissible way by the
connection to it of another device, by any feature of the connected device itself or by any remote
device that communicates with the meter.
The manufacturer shall provide the documentation and tools, which are necessary to verify that these
requirements are met. The requirements of Table 9 for operation of auxiliary devices apply.
– 23 – EN 50470-3:2006
Annex A
(informative)
The following example shows the calculation of the composite error in the presence of influence
quantities:
– the intrinsic error of a polyphase meter of class index A, measured at Itr, balanced load, cos φ = 1
is + 0,7 %;
– at the same load, within the specified operating temperature range of -10 °C to 55 °C, the largest
additional error observed in the subrange of -10 °C to 5 °C was at -10 °C, its value is - 1,9 %;
– at the same load, within the specified operating voltage range of 0,9 Un to 1,1 Un, the largest
additional error observed was at 1,1 Un, its value is + 0,8 %;
– at the same load, within the specified operating frequency range of 0,98 fn to 1,02 fn, the largest
additional error observed was at 0,98 fn, its value is + 0,3 %.
The calculation should be performed for each test point and each temperature sub-range the same
way.
EN 50470-3:2006 – 24 –
Annex B
(normative)
EUT
U1 U2 U3 N I1 I2 I3
U1 U1=0
U1 Voltages at the meter under test U1=0
U3 U2 U3 U2
U3 U2 U3 U2
Normal condition Earth fault condition
Normal condition Earth fault condition
Annex C
(normative)
Imax
Standard √2
meter
Balancing
V Source E.U.T.
impedance
RB RB
I Source
NOTE 1 The balancing impedance shall be equal to the impedance of the equipment under test (E.U.T.) to ensure the
measurement accuracy.
NOTE 2 The balancing impedance could most conveniently be a meter of the same type as the E.U.T.
NOTE 4 The balancing condition can be checked by measuring the DC component of the current in the common line. To
improve the balancing condition, additional resistors can be introduced in the test branch and the balancing branch.
Current waveform
0.5
-0.5
0.00 3.33 6.67 10.00 13.33 16.67 20.00
Period ms
50%
40%
30%
20%
10%
0%
dc 50Hz 2nd 4th 6th 8th 10th 12th 14th 16th 18th 20th
Harmonic
Voltage
waveform Ur e f
generator
NOTE The reference meter shall measure the total active energy (fundamental + harmonics) in the presence of harmonics.
Fired at 5 ms and 15 ms
1.5
0.5
Current waveform
-1
Rise time of leading edge 0,2 ms ± 0,1 ms
Firing points = 5 ms and 15 ms ± 1 ms
-1.5
0.00 3.33 6.67 10.00 13.33 16.67 20.00
Period ms
70%
60%
Harmonic content compared to 50 Hz
50%
40%
30%
20%
10%
0%
50Hz 3rd 5th 7th 9th 11th 13th 15th 17th 19th 21st
Harmonic
1
Reference waveform (0,5 Ib or 0,5 In)
Current waveform
0.5
-0.5
-1
-1.5
0.0 8.0 16.0 24.0 32.0 40.0 48.0 56.0 64.0 72.0 80.0
Period ms
60%
50 Hz component
Harmonic and sub-harmonic content
50%
40%
30%
20%
10%
0%
12.5 37.5 62.5 87.5 112.5 137.5 162.5 187.5 212.5 237.5
Frequency Hz
Annex ZZ
(informative)
This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and within its scope the standard covers all
relevant essential requirements as given in Annex I and Annex MI-003 of the EC Directive 2004/22/EC
of the European Parliament and of the Council on Measuring Instruments.
Compliance with this standard provides one means of conformity with the specified essential
requirements of the Directive concerned.
WARNING: Other requirements and other EC Directives may be applicable to the products falling
within the scope of this standard.
– 31 – EN 50470-3:2006
Bibliography
1)
IEC 62058-11 Electricity metering equipment (a.c.) – Acceptance inspection –
Part 11: General acceptance inspection methods
1)
IEC 62058-31 Electricity metering equipment (a.c.) – Acceptance inspection –
Part 31: Particular requirements for static meters for active energy
(classes 0,5S, 1 and 2)
1)
IEC 62059-31 Electricity metering equipment – Dependability – Part 31: Accelerated
reliability testing
IEC/TR 62059-11 2002 Electricity metering equipment – Dependability – Part 11: General
concepts
IEC/TR 62059-21 2002 Electricity metering equipment – Dependability – Part 21: Collection of
meter dependability data from the field
———————
1)
At draft stage.