इंटरनेट मानक

Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to
information for citizens to secure access to information under the control of public authorities,
in order to promote transparency and accountability in the working of every public authority,
and whereas the attached publication of the Bureau of Indian Standards is of particular interest
to the public, particularly disadvantaged communities and those engaged in the pursuit of
education and knowledge, the attached public safety standard is made available to promote the
timely dissemination of this information in an accurate manner to the public.

“जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न' 5 तरफ”

Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru
“The Right to Information, The Right to Live” “Step Out From the Old to the New”

IS 14570 (2012): Electrical Measuring Transducers for

Converting a.c. Electrical Quantities to Analogue or
Digital Signals [ETD 12: Measuring Equipment for Basic
Electrical Quantities]

“!ान $ एक न' भारत का +नम-ण”

Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह”

है”
ह
Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
 IS 14570 : 2012
IEC 60688 : 2002

Hkkjrh; ekud
,-lh- fo|qr ek=kkvksa vFkok ,ukykWx ;k fMftVy laosQrksa
dks ifjofrZr djus osQ fy, fo|qr ekiu Vªk¡lM~;wllZ
( igyk iqujh{k.k )

Indian Standard
ELECTRICAL MEASURING TRANSDUCERS FOR
CONVERTING ac ELECTRICAL QUANTITIES
TO ANALOGUE OR DIGITAL SIGNALS
( First Revision )

ICS 17.220.20

© BIS 2012
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002

May 2012 Price Group 11

Measuring Equipment for Basic Electrical Quantities Sectional Committee, ETD 12

NATIONAL FOREWORD

This Indian Standard (First Revision) which is identical with IEC 60688 : 2002 ‘Electrical measuring
transducers for converting a.c. electrical quantities to analogue or digital signals’ issued by the
International Electrotechnical Commission (IEC) was adopted by the Bureau of Indian Standards on
the recommendation of the Measuring Equipment for Basic Electrical Quantities Sectional Committee
and approval of the Electrotechnical Division Council.

This standard was first published in 1998. This revision has been undertaken in order to align with
the latest version of IEC 60688 : 2002.

The text of IEC Standard has been approved as suitable for publication as an Indian Standard without
deviations. Certain conventions are, however, not identical to those used in Indian Standards.
Attention is particularly drawn to the following:
a) Wherever the words ‘International Standard’ appear referring to this standard, they should be
read as ‘Indian Standard’.
b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice
is to use a point (.) as the decimal marker.

In this adopted standard, reference appears to certain International Standards for which Indian
Standards also exist. The corresponding Indian Standards which are to be substituted in their respective
places are listed below along with their degree of equivalence for the editions indicated:
International Standard Corresponding Indian Standard Degree of Equivalence
IEC 60050 (301, 302, 303) : 1983 IS 1885 (Part 80) : 1994 Identical to
International Electrotechnical Electrotechnical vocabulary: Part 80 IEC 50-301 : 1983
Vocabulary (IEV) — Chapter 301: General terms on measurements in
General terms on measurements in electricity
electricity. Chapter 302: Electrical
measuring instruments
IS 1885 (Part 81) : 1993 Identical
Electrotechnical vocabulary: Part 81
Electrical measuring instruments
IEC 60051-1 : 1997 Direct acting IS 1248 (Part 1) : 2003 Direct acting Technically Equivalent
indicating analogue electrical indicating analogue electrical
measuring instruments and their measuring instruments and their
accessories — Part 1: Definitions accessories: Part 1 Definitions and
and general requirements common general requirements
to all parts
IEC 60068-2-3 : 1985 Environmental IS 9000 (Part 4) : 1979 Basic do
testing — Part 2: Test Ca: Damp environmental testing procedures for
heat, steady state electronic and electrical items: Part 4
Damp heat (steady state)
1)
IEC 60255-4 : 1976 Electrical relays IS 3231 (Part 1/Sec 3) : 1986 do
— Part 4: Single input energizing Electrical relays for power system
quantity measuring relays with protection: Part 1 General
dependent specified time requirements, Section 3 High
frequency distrubance test for static
relays

1)
This publication has been replaced by IEC 60255-3 : 1989.
(Continued on third cover)
 IS 14570 : 2012
IEC 60688 : 2002

Indian Standard
ELECTRICAL MEASURING TRANSDUCERS FOR
CONVERTING ac ELECTRICAL QUANTITIES
TO ANALOGUE OR DIGITAL SIGNALS
( First Revision )

1 Scope

This International Standard applies to transducers with electrical inputs and outputs for
making measurements of a.c. electrical quantities. The output signal may be in the form of an
analogue direct current or in digital form. In this instance, that part of the transducer utilized for
communication purposes will need to be compatible with the external system.

This standard applies to measuring transducers used for converting alternating electrical
quantities such as:

– current
– voltage
– active power
– reactive power
– power factor
– phase angle
– frequency

to an output signal.

Within the measuring range, the output signal is a function of the measurand. An auxiliary
supply may be needed.

This standard applies:

a) if the nominal frequency of the input(s) lies between 5 Hz and 1 500 Hz;
b) if a measuring transducer is part of a system for the measurement of a non-electrical
quantity, this standard may be applied to the electrical measuring transducer, if it
otherwise falls within the scope of this standard;
c) to transducers for use in a variety of applications such as telemetry and process control
and in one of a number of defined environments.

This International Standard is intended:

– to specify the terminology and definitions relating to transducers whose main application is
in electrical power engineering, especially for the purposes of process control and telemetry
systems;
– to unify the test methods used in evaluating transducer performance;
– to specify accuracy limits and output values for transducers.

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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.

IEC 60050(301, 302, 303):1983, International Electrotechnical Vocabulary (IEV). Chapter 301:
General terms on measurements in electricity. Chapter 302: Electrical measuring instruments.
Chapter 303: Electronic measuring instruments

IEC 60051-1:1997, Direct acting indicating analogue electrical measuring instruments and their
accessories – Part 1: Definitions and general requirements common to all parts

IEC 60068-2-3:1985, Environmental testing – Part 2: Tests – Test Ca: Damp heat, steady state

IEC 60255-4 * :1976, Electrical relays – Part 4: Single input energizing quantity measuring relays
with dependent specified time

IEC 60521:1988, Class 0,5, 1 and 2 alternating-current watt-hour meters

IEC 61000-4, Electromagnetic compatibility (EMC) – Part 4: Testing and measuring techniques

IEC 61010-1:2001, Safety requirements for electrical equipment for measurement, control and
laboratory use – Part 1: General requirements
NOTE Refer to annex A for the list of informative references.

3 Definitions

For the purpose of this International Standard the following definitions apply:

3.1 General terms

3.1.1
electrical measuring transducer (hereinafter designated "transducer")
a device for converting an a.c. measurand to a direct current, a direct voltage or a digital signal
for measurement purposes

3.1.2
auxiliary supply
an a.c. or d.c. electrical supply, other than the measurand, which is necessary for the correct
operation of the transducer

3.1.3
auxiliary circuit
a circuit which is usually energized by the auxiliary supply.
NOTE The auxiliary circuit is sometimes energized by one of the input quantities.

___________
* This publication has been replaced by IEC 60255-3:1989.

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3.1.4
transducer with offset zero (live zero)
a transducer which gives a predetermined output signal other than zero when the measurand
is zero

3.1.5
transducer with suppressed zero
a transducer for which zero output signal corresponds to a measurand greater than zero

3.1.6
distortion factor
the ratio of the r.m.s. value of the harmonic content to the r.m.s. value of the non-sinusoidal
quantity

3.1.7
output load (for analogue signals only)
the total resistance of the circuits and apparatus connected externally across the output
terminals of the transducer

3.1.8
ripple content (of an analogue output signal)
with steady-state input conditions, the ratio of the peak-to-peak value of the fluctuating
component of an analogue output signal, expressed in percentage, to the fiducial value

3.1.9
output signal
an analogue or digital representation of the measurand

3.1.10
output power
the power at the transducer output terminals

3.1.11
output current (voltage) (for analogue signals only)
the current (voltage) produced by the transducer which is an analogue function of the
measurand

3.1.12
reversible output current (voltage) (for analogue signals only)
an output current (voltage) which reverses polarity in response to a change of sign or
direction of the measurand

3.1.13
measuring element of a transducer
a unit or module of a transducer which converts the measurand, or part of the measurand, into
a corresponding signal.

3.1.14
single element transducer
a transducer having one measuring element

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3.1.15
multi-element transducer
7a transducer having two or more measuring elements. The signals from the individual
elements are combined to produce an output signal corresponding to the measurand

3.1.16
multi-section transducer
a transducer having two or more independent measuring circuits for one or more functions

3.1.17
response time
the time from the instant of application of a specified change of the measurand until the output
signal reaches and remains at its final steady value or within a specified band centred on this
value

3.1.18
compliance voltage (accuracy limiting output voltage)
for variable output load transducers having a current output, the value of the voltage
appearing across the output terminals up to which the transducer complies with the
requirements of this standard

3.1.19
(output) series mode interference voltage
an unwanted alternating voltage appearing in series between the output terminals and the load

3.1.20
(output) common mode interference voltage
an unwanted alternating voltage which exists between each of the output terminals and a
reference point

3.1.21
storage conditions
the conditions, defined by means of the ranges of the influence quantities, such as temperature
or any other special condition, within which the transducer may be stored (non-operating)
without damage

3.1.22
stability
the ability of a transducer to keep its performance characteristics unchanged during a speci-
fied time, all influence quantities remaining within their specified ranges

3.1.22.1
short-term stability
the stability over a period of 24 h

3.1.22.2
long-term stability
the stability over a period of one year

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3.1.23
usage group
a group of transducers capable of operating under a specified set of environmental conditions

3.2 Description of transducers according to the measurand

3.2.1
voltage transducer
a transducer used for the measurement of a.c. voltage

3.2.2
current transducer
a transducer used for the measurement of a.c. current

3.2.3
active power (watt) transducer
a transducer used for the measurement of active electrical power

3.2.4
reactive power (var) transducer
a transducer used for the measurement of reactive electrical power

3.2.5
frequency transducer
a transducer used for the measurement of the frequency of an a.c. electrical quantity

3.2.6
phase angle transducer
a transducer for the measurement of the phase angle between two a.c. electrical quantities
having the same frequency

3.2.7
power factor transducer
a transducer used for the measurement of the power factor of an a.c. circuit

3.3 Description of transducers according to their output load

3.3.1
fixed output load transducer
a transducer which complies with this standard only when the output load is at its nominal
value, within specified limits

3.3.2
variable output load transducer
a transducer which complies with this standard when the output load has any value within a
given range

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3.4 Nominal values

3.4.1
nominal value
a value, or one of the values, indicating the intended use of a transducer
NOTE The lower and upper nominal values of the measurand are those which correspond to the lower and upper
nominal values of the output signal.

3.4.2
output span (hereinafter designated "span")
the algebraic difference between the upper and lower nominal values of the output signal

3.4.3
fiducial value
a value to which reference is made in order to specify the accuracy of a transducer

The fiducial value is the span, except for transducers having a reversible and symmetrical
output signal when the fiducial value may be half the span if specified by the manufacturer.

3.4.4
circuit insulation voltage (nominal circuit voltage)
the highest circuit voltage to earth on which a circuit of a transducer may be used and which
determines its voltage test

3.4.5
nominal power factor
the factor by which it is necessary to multiply the product of the nominal voltage and nominal
current to obtain the nominal power

nominal power
Nominal power factor =
nominal voltage × nominal current

When the current and voltage are sinusoidal quantities, the nominal power factor is cos ϕ, ϕ
being the phase difference between the current and the voltage. For reactive power
transducers, the nominal power factor is sin ϕ.

3.4.6
maximum permissible values of input current and voltage
values of current and voltage assigned by the manufacturer as those which the transducer will
withstand indefinitely without damage

3.4.7
limiting value of the output (current or voltage) signal
the upper limit of output (current or voltage) signal which cannot, by design, be exceeded
under any conditions

3.4.8
measuring range
the range defined by two values of the measurand within which the performance complies with
the requirements of this standard (see 2.4.3 of IEC 60051-1)

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3.4.9
nominal value of the measured voltage
the nominal value of the voltage of the external circuit (e.g. the secondary winding of a voltage
transformer) to which the voltage input circuit of the transducer is to be connected

3.4.10
nominal value of the measured current
the nominal value of the current in the external circuit (e.g. the secondary winding of a current
transformer) to which the current input circuit of the transducer is to be connected

3.4.11
nominal value of the measurand
for active power and reactive power transducers, the value of the measured quantity corres-
ponding to the nominal values of the measured voltage and current, and the power factor

3.5
user adjustment
transducers can be supplied with provision to be adjusted by the user. (It should be noted that
power sources and measuring equipment having adequate stability and accuracy are required).
The following definitions apply to these transducers

3.5.1
calibration value
the value of a quantity to which the nominal value is changed by user adjustment for a specific
application

3.5.2
calibration value of the measured voltage
the value of the voltage applied to the voltage input circuit of the transducer

3.5.3
calibration value of the measured current
the value of the current applied to the current input circuit of the transducer

3.5.4
calibration value of the measurand
the value of the measurand resulting from user adjustment

3.5.5
calibration value of the output signal
the value of the output signal of the transducer corresponding to the calibration value of
the measurand after adjustment

3.5.6
adjustment range
the possible range of adjustment values of the measured current or voltage

3.5.7
conversion coefficient
the relationship of the value of the measurand to the corresponding value of the output signal

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3.6 Influence quantities and reference conditions

3.6.1
influence quantity
a quantity (other than the measurand) which may affect the performance of a transducer

3.6.2
reference conditions
the specified conditions under which the transducer complies with the requirements
concerning intrinsic errors. These conditions may be defined by either a reference value or a
reference range

3.6.2.1
reference value
a specified single value of an influence quantity at which the transducer complies with the
requirements concerning intrinsic errors

3.6.2.2
reference range
a specified range of values of an influence quantity within which the transducer complies
with the requirements concerning intrinsic errors

3.6.3
nominal range of use
a specified range of values which it is intended that an influence quantity can assume without
the output signal of the transducer changing by amounts in excess of those specified

3.7 Errors and variations

3.7.1
error
the actual value of the output signal minus the intended value of the output signal,
expressed algebraically

3.7.2
error expressed as a percentage of the fiducial value
one hundred times the ratio of the error and the fiducial value

3.7.3
intrinsic error
an error determined when the transducer is under reference conditions

3.7.4
variation due to an influence quantity
the difference between the two values of the output signal for the same value of the
measurand when an influence quantity assumes successively two different specified values

3.7.5
variation due to an influence quantity expressed as a percentage of the fiducial value
one hundred times the ratio of the variation due to an influence quantity and the fiducial
value

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3.8 Accuracy, accuracy class, class index

3.8.1
accuracy
the accuracy of a transducer is defined by the limits of intrinsic error and by the limits of
variations

3.8.2
accuracy class
a class of transducers the accuracy of all of which can be designated by the same number if
they comply with all the requirements of this standard

3.8.3
class index
the number which designates the accuracy class
NOTE 1 The class index is applicable to the intrinsic error as well as to the variations.
NOTE 2 Throughout this standard, the phrase "x % of the class index" denotes "x % of the limits of error relating
to the class index".

4 Class index, permissible limits of intrinsic error, auxiliary supply and

reference conditions

4.1 Class index

The class index for a transducer shall be chosen from those given in table 1.

Table 1 – Relationship between the limits of intrinsic error,

expressed as a percentage of the fiducial value, and the class index

Class index 0,1 0,2 0,5 1

Limits of error ±0,1 % ±0,2 % ±0,5 % ±1 %

NOTE Class indices of 0,3 and 1,5, although non-preferred, may be used.

4.2 Intrinsic error

When the transducer is under reference conditions, the error at any point between the upper
and lower nominal values of the output signal shall not exceed the limits of the intrinsic
error given in table 1 expressed as a percentage of the fiducial value.

Values stated in a table of corrections, if any, supplied with the transducer shall not be taken
into account in determining the errors.

4.3 Conditions for the determination of intrinsic error

4.3.1 Prior to pre-conditioning and before determination of the intrinsic error, preliminary
adjustments shall be carried out in accordance with the manufacturer's instructions. The
transducer shall be at the reference temperature.

4.3.2 The transducer shall be left in circuit under the conditions specified in table 2.

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4.3.3 After the specified pre-conditioning, transducers having adjustments available to the
user shall be adjusted in accordance with the manufacturer's instructions.

4.3.4 The reference conditions relative to each of the influence quantities are given in
table 3. The reference conditions relative to the measurand are given in table 4.

Table 2 – Pre-conditioning

Conditions Values

Voltage (including any auxiliary supply) Nominal value

Current Nominal value

Frequency Reference value
Power factor Reference value
Time between connection into circuit and 30 min
start of determination of errors

4.4 Auxiliary supply

Some transducers dealt with in this standard may need an auxiliary supply. This is specified
in two separate categories, d.c. and a.c. supplies.

4.4.1 D.C. supply

a) The value of the voltage of the d.c. supply shall be as specified in 5.1.2.
b) The battery supply may be earthed or floating. Suitable means shall be provided in the
transducer to ensure isolation between the power supply and the input/output circuits of
the transducer (for details of voltage tests, see 6.19).
c) The transducer shall withstand any ripple up to a maximum of 10 % peak to peak,
superimposed on the d.c. power supply.
d) The noise fed back to the battery from the transducer shall be limited to 100 mV peak to
peak when measured with a specified source resistance at all frequencies up to 100 MHz.

In addition, when the battery feeding the transducer is also used for telephone equipment the
noise shall not exceed 2 mV psophometric.
NOTE The psophometric weighting characteristic is given in CCITT recommendation P 53.

4.4.2 A.C. supply

For the nominal value of the voltage of the a.c. supply see 5.1. This voltage may be provided
by a separate supply or may be derived from the measured voltage.

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Table 3 – Reference conditions of the influence quantities and

tolerances or testing purposes

Influence quantity Reference conditions Tolerances permitted for testing

unless otherwise marked purposes applicable to a single
reference value (note 1)
Ambient temperature To be marked
Usage group (see 6.1.2)
I 20, 23 or 27 °C ±1 °C
II 15 ... 30 °C –
III 0 ... 45 °C –
Frequency of the input quantity
Non frequency sensitive Nominal value ±2 %
Frequency sensitive To be marked ±0,1 %
Waveform of the input quantity Sinusoidal The distortion factor × 100 shall not
exceed the class index, unless
otherwise specified by the manufacturer
Output load
Fixed output load transducers Nominal value ±1 %
Variable output load transducers Mean value of the nominal ±1 %
range
Auxiliary supply
Voltage a.c. Nominal value ±2 %
Voltage d.c. Nominal value ±1 %
Frequency Nominal value ±1 %
Distortion factor 0,05 –
Magnetic field of external origin Total absence 40 A/m at frequencies from d.c. to 65 Hz
in any direction (note 2)
NOTE 1 When a reference range is marked, no tolerance is allowed.
NOTE 2 40 A/m is approximately the highest value of the earth's magnetic field.

Table 4 – Reference conditions relative to the measurand

Reference conditions
Measurand Voltage Current Power factor, active or
reactive
Active power Nominal voltage ±2 % Any current up to the cos ϕ = 1,0 ... 0,8
nominal current lagging or leading
Reactive power Nominal voltage ±2 % Any current up to the sin ϕ = 1,0 ... 0,8
nominal current lagging or leading (note 1)
Phase angle or power factor Nominal voltage ±2 % 40 ... 100 % of the nominal –
current
Frequency Nominal voltage ±2 % – –
Polyphase quantities Symmetrical voltages Symmetrical currents –
(note 2) (note 2)
NOTE 1 Active power and reactive power transducers are normally used together and are connected to the
same current and voltage transformers. It must be noted that sin ϕ = 1,0 ... 0,8 is used here for ease of testing
only.
NOTE 2 The difference between any two line-to-line voltages and between any two line-to-neutral voltages shall
not exceed 1 % of the average (line-to-line and line-to-neutral voltages respectively).
Each of the currents in the phases shall differ by not more than 1 % from the average of the currents.
The angles between each of the currents and the corresponding phase-to-neutral (star) voltages shall differ by not
more than 2°.
Where interactions between the separate measuring elements of a multi-element transducer are adequately
characterized, single-phase testing of the transducer is acceptable.

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5 Requirements

5.1 Input values

The nominal values of voltage, current, frequency and auxiliary supply shall be specified by
the manufacturer.

5.1.1 Adjustment range for transducers which can be adjusted by the user:

a) for the input voltage: 80 ... 120 % of the nominal value;

b) for the input current: 60 ... 130 % of the nominal value.

This means that the nominal value of the output signal can be obtained for any adjusted
value of the measurand within the ranges given above.

5.1.2 The preferred nominal value of d.c. auxiliary supplies shall be 24 V, 48 V or 110 V.

5.2 Analogue output signals

The lower and upper nominal values of the output signal and the compliance voltage shall
be chosen from those given in 5.2.1 and 5.2.2 or 5.2.5.

5.2.1 Output current

The signal 4 ... 20 mA is preferred.

NOTE The condition "0 mA" has a special meaning (IEC 60381-1).

Other permissible values are:

0 ... 20 mA
0 ... 1 mA
0 ... 10 mA
–1 ... 0 ... 1 mA
–10 ... 0 ... 10 mA

5.2.2 Compliance voltage

10 V
15 V

5.2.3 The manufacturer shall state the maximum value of the output voltage occurring under
any conditions of output load and input. This voltage shall not exceed the limit of safety extra-
low voltage.

5.2.4 Attention is drawn to the interference problems which may result if the output current
has a low value.

5.2.5 Output voltage

0 ... 1 V
0 ... 10 V
–1 ... 0 ... 1 V
–10 ... 0 ... 10 V
NOTE Transducers having a voltage output are non-preferred.

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5.3 Digital output signals

The digital output signals chosen shall correspond with the requirements for transducers
concerning accuracy and response time as well as with the requirements of the
communication system.

5.4 Ripple (for analogue outputs)

The maximum ripple content in the output signal shall not exceed twice the class index.

5.5 Response time

5.5.1 Before determining the response time, the transducer shall be under reference
conditions and the auxiliary circuit shall be energized for at least the pre-conditioning time
unless it is energized from one of the input quantities and is not separately accessible.

5.5.2 The response time shall be stated by the manufacturer and shall be determined for an
input step such that it would produce a change in output signal from 0 % to 90 % of the
fiducial value.

5.5.3 If a test for decreasing input is required, the input step should produce a change in
output signal from 100 % to 10 % of the fiducial value.

5.5.4 The band (see 3.1.17) shall be ±1 % of the upper nominal value of the output signal.

5.5.5 Methods of test for frequency transducers and transducers with suppressed zero
shall be stated by the manufacturer.

5.6 Variation due to over-range of the measurand

If, by agreement, a transducer is required to operate with an input up to 150 % of the nominal
value, the difference between the intrinsic error at 100 % and the error at 150 % (under
reference conditions) of the nominal value of the input shall not exceed 50 % of the class
index.

For active power and reactive power transducers, 150 % of the nominal value is achieved
by increasing the current while retaining the voltage at the nominal value.

5.7 Limiting value of the output signal

The output signal shall be limited to a maximum of twice the upper nominal value.

When the measurand is not between its lower and upper nominal values, the transducer shall
not, under any conditions, for example over-current or under-voltage, produce an output having
a value between its lower and upper nominal values.

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5.8 Limiting conditions of operation

The limits of the nominal ranges of use given in clause 6 are those within which the
transducer will comply with the requirements of this standard. It is possible to operate
transducers beyond these limits but the user should note that:

– the accuracy may not be maintained and/or

– the designed operational lifetime may be reduced.

As an example, many transducers will operate in ambient temperatures as low as –25 °C and
as high as +70 °C but the manufacturer should be consulted as to the degradation to be
expected in both accuracy and operational lifetime.

5.9 Limits of the measuring range

When the limits of the measuring range do not coincide with the lower and upper nominal
values of the output, the limits of the measuring range shall be marked (see 7.1 i)).

5.10 Limiting conditions for storage and transport

Unless otherwise stated by the manufacturer, transducers shall be capable of withstanding,

without damage, exposure to temperatures within the range –40 °C to +70 °C.

After returning to reference conditions, they shall meet the requirements of this standard.

The manufacturer shall specify any additional limiting condition required to ensure the integrity
of the transducer.

5.11 Sealing

When the transducer is sealed to prevent unauthorized adjustment, access to the internal
circuit and to the components within the case shall not be possible without destroying the seal.

5.12 Stability

Transducers shall comply with the relevant limits of intrinsic error specified for their
respective accuracy classes for a period specified by the manufacturer, provided that the
conditions of use, transport and storage specified by the manufacturer are complied with.
NOTE Usually the period will not exceed one year.

6 Tests

6.1 General

6.1.1 Determination of variations

The variations shall be determined for each influence quantity. During the tests, all other
influence quantities shall be maintained at reference conditions.

All the influence quantities are given in the following subclauses, together with the
appropriate testing procedure, computations and the permissible variations for each Usage
group expressed as a percentage of the class index. None of the variations determined shall
exceed the permissible values.

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Variations shall be determined at the upper nominal value of the output and, at least, at one
other point. For active power and reactive power transducers, these values shall be
obtained by maintaining the voltage and power factor at their reference conditions and
varying the value of the current.

When a reference range is specified, the influence quantity shall be varied between each of
the limits of the reference range and any value in that part of the nominal range of use which
is adjacent to the chosen limit of the reference range.

6.1.2 Environmental conditions

The conditions of temperature and humidity are classified according to the severity dictated by
the usage group in accordance with table 5.

The usage groups given in the table correspond to the following definitions.

I For indoor use and under conditions which are normally found in laboratories and factories
and where apparatus will be handled carefully.
II For use in locations having protection from full extremes of environment and under
conditions of handling between those of Groups I and III.
III For outdoor use and in areas where the apparatus may be subjected to rough handling.

Table 5 – Usage groups

Usage group Nominal range of use Relative humidity

for temperature

I 10 ...35 °C 
 +2
II 0 ... 45 °C  Up to 93 −3 %

III –10 ... 55 °C 
NOTE For testing purposes, reference should be made to IEC 60068-2-3.

For the purpose of this standard, ambient temperature shall be the temperature measured at a
single representative point with the transducer operating normally. This measuring point shall
be adjacent to the transducer, exposed to free air circulation and not significantly affected by
heat from the transducer nor by direct solar radiation and other sources of heat.

Humidity is not considered to be an influence quantity provided that the environmental

conditions are within the limits specified.

6.1.3 Computations

In the following subclauses, a computation is required according to a formula. The terms in the
formulae follow a general principle:

– R is the value of the output signal under reference conditions.

– X (or Y) is the value of the output signal measured at one extreme of the influence
quantity.
– F is the fiducial value.

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6.2 Variations due to auxiliary supply voltage

6.2.1 Application

All transducers requiring a d.c. or an a.c. auxiliary supply except where this is obtained from
the input voltage and the connections cannot be separated for testing purposes.

6.2.2 Procedure

Apply the nominal value of auxiliary supply voltage and record the value of the output
signal (R).

At a constant value of the measurand, reduce the auxiliary supply voltage to the lower limit
given in 6.2.4 and record the value of the output signal (X). Increase the auxiliary supply
voltage to the upper limit given in 6.2.4 and record the value of the output signal (Y).

6.2.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

6.2.4 Permissible variations

For a.c. auxiliary supplies

Usage group Nominal range Variation

of use
I 90 ... 110 % 50 %
II 80 ... 120 % 50 %
III 80 ... 120 % 50 %

For d.c. auxiliary supplies

Usage group Nominal range Variation

of use
I 85 ... 125 % 50 %
II 85 ... 125 % 50 %
III 85 ... 125 % 50 %

6.3 Variations due to auxiliary supply frequency

6.3.1 Application

All transducers requiring an a.c. auxiliary supply except where this is obtained from the input
voltage and the connections cannot be separated for testing purposes.

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6.3.2 Procedure

Apply the nominal value of auxiliary supply frequency and record the value of the output
signal (R). At a constant value of the measurand, reduce the auxiliary supply frequency to
the lower limit given in 6.3.4 and record the value of the output signal (X).

Increase the auxiliary supply frequency to the upper limit given in 6.3.4 and record the value
of the output signal (Y).

6.3.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

6.3.4 Permissible variations

Usage group Nominal range Variation
of use
I 90 ... 110 % 50 %
II 90 ... 110 % 50 %
III 90 ... 110 % 50 %

6.4 Variations due to ambient temperature

6.4.1 Application

All transducers.

6.4.2 Procedure

At a constant value of the measurand and at reference temperature, record the value of the
output signal (R).

Increase the ambient temperature to the upper limit given in 6.4.4 and allow sufficient time for
conditions to stabilize (30 min is usually adequate). Record the value of the output signal (X).

Reduce the ambient temperature to the lower limit given in 6.4.4 and allow the same
stabilization to take place. Record the value of the output signal (Y).

6.4.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

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6.4.4 Permissible variations

Usage group Nominal range Variation
of use
I 10 ... 35 °C 100 %
II 0 ... 45 °C 100 %
III –10 ... 55 °C 100 %

6.5 Variations due to the frequency of the input quantity(ies)

6.5.1 Application

All transducers except frequency transducers. Frequency sensitive transducers (e.g. those
employing phase shifting circuits) are exceptions and the nominal range of use shall always
be marked.

6.5.2 Procedure

Apply the nominal value of the input frequency and record the value of the output signal (R).

At a constant value of the measurand, reduce the frequency to the lower limit given in 6.5.4
and record the value of the output signal (X).

Increase the frequency to the upper limit given in 6.5.4 and record the value of the output
signal (Y).

6.5.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

6.5.4 Permissible variations

Usage group Nominal range Variation
of use
I 90 ... 110 % 100 %
II 90 ... 110 % 100 %
III 90 ... 110 % 100 %
Frequency
sensitive As marked 100 %

6.6 Variations due to the input voltage

6.6.1 Application

All transducers except voltage and current transducers.

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6.6.2 Procedure

Apply the nominal value of the input voltage and record the value of the output signal (R).

At a constant value of the measurand, reduce the voltage to the lower limit given in 6.6.4 and
record the value of the output signal (X).

Increase the voltage to the upper limit given in 6.6.4 and record the value of the output
signal (Y).

6.6.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

6.6.4 Permissible variations

Usage group Nominal range Variation
of use
I 90 ... 110 % 50 %
II 8 ... 120 % 50 %
III 8 ... 120 % 50 %

6.7 Variations due to the input current

6.7.1 Application

Phase angle and power factor transducers.

6.7.2 Procedure

Apply the nominal value of the input current and record the value of the output signal (R).

At a constant value of the measurand, reduce the input current to the lower limit given in 6.7.4
and record the value of the output signal (X).

Increase the input current to the upper limit given in 6.7.4 and record the value of the output
signal (Y).

6.7.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

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6.7.4 Permissible variations

Usage group Nominal range Variation
of use
I 20 ... 120 % 100 %
II 20 ... 120 % 100 %
III 20 ... 120 % 100 %

6.8 Variations due to power factor

6.8.1 Application

Active and reactive power transducers.

6.8.2 Procedure

Apply 50 % (5 %) of the nominal value of the input current at a power factor of 1,0 lag/lead
respectively and record the two values of the output signal (R). At a constant value of the
measurand, increase the input current to 100 % (10 %) of the nominal value and reduce the
power factor to 0,5 lag/lead, respectively. Record the two values of the output signal (X).

For convenience, when testing the reactive power transducers, it is usual to apply the
equivalent values of sin ϕ .

Active power transducers shall also be tested for error at a power factor of zero and reactive
power transducers at a sin ϕ = 0.

6.8.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

6.8.4 Permissible variations

Usage group Nominal range of use Variation
I Cos (sin) ϕ = 0,5 ... 1 ... 0,5 50 %
II Cos (sin) ϕ = 0,5 ... 1 ... 0,5 50 %
III Cos (sin) ϕ = 0,5 ... 1 ... 0,5 50 %

For all transducers, the error at a power factor of zero (or sin ϕ = 0) shall not exceed 100 % of
the class index.

6.9 Variation due to output load

6.9.1 Application

All variable output load transducers.

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6.9.2 Procedure

Apply a value of output load equal to the mean value of the nominal range and record the
value of the output signal (R).

At a constant value of the measurand, reduce the resistance of the output load to the lower
limit given in 6.9.4 and record the value of the output signal (X).

Increase the resistance of the output load to the upper limit given in 6.9.4 and record the
value of the output signal (Y).

6.9.3 Computation

X −R
The variations are: × 100
F

Y −R
and: × 100
F

6.9.4 Permissible variations

Usage group Nominal range Variation
OF USE
I 10 ... 100 % 50 %
II 10 ... 100 % 50 %
III 10 ... 100 % 50 %

6.10 Variations due to distortion of the input quantity(ies)

6.10.1 Application

All transducers characterized by the manufacturer for use on systems having distorted
waveforms.

6.10.2 Procedure

Apply the chosen value of input quantity with no distortion and record the value of the output
signal (R). Introduce third harmonic distortion at the level given in 6.10.4, maintaining the
r.m.s. values constant, and record the value of the output signal (X). The phase relationship
between the harmonic and the fundamental should be varied so as to determine the most
unfavourable conditions.

For active and reactive power transducers, the test is performed with distorted current
waveform and then repeated with distorted voltage waveform.

For active and reactive power transducers not employing phase shifters, the permissible
variations are given in 6.10.4.

For reactive power transducers employing phase shifters, the permissible variations shall be
specified by the manufacturer.

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6.10.3 Computation

X −R
La variation est: × 100
F

6.10.4 Permissible variations

Usage group Nominal range of use Variation
I Distortion factor 0,2 200 %
II Distortion factor 0,2 200 %
III Distortion factor 0,2 200 %

6.11 Variation due to magnetic field of external origin

6.11.1 Application

All transducers.

6.11.2 Procedure

The transducer is placed in the centre of a coil of 1 m mean diameter, of square cross section
and of radial thickness small compared with the diameter (Note). 400 ampere-turns in this coil
will produce, at the centre of the coil, in the absence of the transducer under test, a magnetic
field strength of 0,4 kA/m. The magnetic field shall be produced by a current of the same kind
and frequency as that which energizes the measuring circuit and shall be such as to have the
most unfavourable combination of phase and orientation. The values of a.c. fields are
expressed in r.m.s. values.

Any transducer having an external dimension exceeding 250 mm shall be tested in a coil of
mean diameter not less than four times the maximum dimensions of the transducer. The
magnetic field strength being the same as that given above.
NOTE Other devices which produce an adequate homogeneous magnetic field in the absence of the transducer
under test are also permissible.

In the absence of the external field, record the value of the output signal (R).

At a constant value of the measurand, apply the external field and record the value of the
output signal (X).

6.11.3 Computation

X −R
The variation is: × 100
F

6.11.4 Permissible variations

Usage group Variation
I 100 %
II 100 %
III 100 %

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6.12 Variation due to unbalanced currents

6.12.1 Application

Multi-element active and reactive power transducers.

6.12.2 Procedure

The currents shall be balanced and adjusted so that the output signal is approximately in the
middle of the span or, if zero output signal is within the span, half-way between zero and the
upper nominal value of the output signal. Record the value of the output signal (R).

Disconnect one current, maintaining the voltages balanced and symmetrical, and adjust the
other currents, maintaining them equal, so as to restore the initial value of the measurand.

Record the value of the output signal (X).

6.12.3 Computation

X −R
The variation is: × 100
F

6.12.4 Permissible variations

Usage group Variation
I 100 %
II 100 %
III 100 %

6.13 Variation due to interaction between measuring elements

6.13.1 Application

All multi-element active power and reactive power transducers except those employing two
measuring elements for measuring three-phase four-wired unbalanced power with three current
circuits (sometimes known as "two and a half elements") and those reactive power
transducers using cross-connection methods.

6.13.2 Procedure

The voltage input of one measuring circuit alone shall be energized at nominal voltage. The
current input of each of the other measuring circuits shall be energized in turn at nominal
current. The maximum departure of the output signal (X) from that corresponding to zero of
the measurand shall be noted whilst the phase angle between the voltage and currents is
changed through 360°.

If the auxiliary supply is common to one of the voltage input circuits, this circuit shall be the
one to which the voltage is applied.

6.13.3 Computation

X
The variation is: × 100
F

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6.13.4 Permissible variations

Usage group Variation
I 50 %
II 50 %
III 50 %

6.14 Variation due to self-heating

6.14.1 Application

All transducers.

6.14.2 Method

The transducer shall be at ambient temperature and shall have been disconnected for at least
4 h. Energize the transducer in accordance with 4.3.2 (except for the condition of "30 min" as
specified in table 2).

After 1 min and before the third minute, determine the value of the output signal (X). Repeat
this procedure between the 30th and 35th minute after energization (R).

6.14.3 Computation

R−X
The variation is: × 100
F

6.14.4 Permissible variations

Usage group Variation
I 100 %
II 100 %
III 100 %

6.15 Variation due to continuous operation

6.15.1 Application

All transducers.

6.15.2 Procedure

Energize the transducer under reference conditions for at least the preconditioning period.
Record the value of the output (R). After a convenient period of continuous operation, for
example 6 h, note the value of the output (X).

6.15.3 Computation

X −R
The variation is: × 100
F

6.15.4 Permissible variation

A variation is allowed but the transducer shall continue to comply in all respects with the
requirements appropriate to its accuracy class.

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6.16 Variation due to common mode interference

6.16.1 Application

All transducers having an analogue output signal.

6.16.2 Procedure

At a constant value of the measurand near the upper nominal value, record the value of the
output signal (R). Apply a voltage of 100 V r.m.s., at 45 Hz to 65 Hz, between either output
terminal and earth. Record the value of the output signal (X).

6.16.3 Computation

X −R
The variation is: × 100
F

6.16.4 Permissible variations

Usage group Variation
I 100 %
II 100 %
III 100 %

6.17 Variation due to series mode interference

6.17.1 Application

All transducers having an analogue current output signal.

6.17.2 Procedure

At a constant value of the measurand near the upper nominal value and with the compliance
voltage at 80 % of the maximum value, record the value of the output signal (R).

Apply a voltage of 1 V r.m.s. at 45 Hz to 65 Hz, in series with the output signal. Record the
value of the output signal (X).
NOTE The internal d.c. resistance of the source of the series-mode interference, if excessive, may influence the
test results, especially for the fixed output load transducers.

6.17.3 Computation

X −R
The variation is: × 100
F

6.17.4 Permissible variations

Usage group Variation
I 100 %
II 100 %
III 100 %

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6.18 Permissible excessive inputs

After completion of the tests described in 6.18.1 and 6.18.2 and after having regained
equilibrium with the reference value of the ambient temperature, the transducer shall comply
with the requirements appropriate to its class index.

6.18.1 Continuous excessive inputs

The transducer shall withstand the application of excessive inputs simultaneously for 24 h.

a) Voltage inputs, including auxiliary supplies, shall be subjected to 120 % of the nominal
value of the voltage.
b) Current inputs shall be subjected to 120 % of the nominal value of the current.

6.18.2 Excessive inputs of short duration

The tests shall be made under reference conditions. The excessive input amplitudes of short
duration which shall be applied to transducers are:

a) for voltage inputs: 200 % of the nominal value of the measured voltage applied for 1 s
and repeated 10 times at 10 s intervals;
b) for current inputs: 20 times the nominal value of the measured current applied for 1 s and
repeated 5 times at 300 s intervals.

The test circuit shall be substantially non-reactive.

6.19 Voltage test, insulation tests and other safety requirements

The requirements for the voltage test and other safety requirements are included in IEC 61010-1
to which reference shall be made.

6.20 Impulse voltage tests

6.20.1 A peak test voltage of 5 kV in both positive and negative senses, having the
standardized impulse waveform of 1,2/50 µs, shall be applied to transducers as follows:

– between the earth terminal and all the other terminals connected together;
– between the terminals of each circuit in turn, all other circuits being earthed.

Three positive and three negative impulses shall be applied at intervals of not less than 5 s.
Any flashover (capacitance discharge) shall be considered a criterion of failure unless
occurring in a component designed for such.

For further details of the impulse voltage test, reference should be made to IEC 60521.

6.20.2 After completion of the impulse voltage test, the transducer shall comply with the
requirements appropriate to its class index.

6.20.3 Auxiliary circuits with a reference voltage of over 40 V shall be subjected to the
impulse voltage test under the same conditions as those already given for the other circuits.

6.21 High frequency disturbance test

See the IEC 61000-4 series of publications.

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6.22 Test for temperature rise

The transducer shall be energized as follows:

– each current circuit shall carry a current of 1,1 times the nominal current and
– each voltage circuit shall be supplied with a voltage of 1,2 times the nominal voltage.

These conditions shall be maintained for at least 2 h. During the test the transducer shall not
be exposed to forced ventilation nor to direct solar radiation.

The temperature rise of the following parts of the transducer shall not exceed:

– for input circuits: 60 K;

– for the exterior surface: 25 K.

6.23 Other tests

If, by agreement, other tests are required, refer to the following publications:

– for vibration: IEC 60068-2-6;

– for shock: IEC 60068-2-27;
– for drop and topple: IEC 60068-2-31;
– for electromagnetic compatibility: the IEC 61000-4 series of publications.

7 Marking

7.1 Marking on the case

Transducers shall bear, on (or visible through) one of the external surfaces of the case, the
markings listed below. The markings shall be legible and indelible. The symbols referred to
below are specified in table 7.

a) Manufacturer's name or mark.

b) Manufacturer's type designation.
c) Serial number or date code.
d) Class index (symbol E-10 or E-11).
e) Nature of the measurand and number of circuits (symbol B-2, B-4 or B-6 to B-10).
f) Lower and upper nominal values of the measurand.
g) Ratios of current transformers and voltage transformers, if any, with which the transducer
is intended to be used.
h) Range of values of the output current (voltage) and output load within which specified
operation is obtained (analogue signals only).
i) Limits of the measuring range, if appropriate (see 5.9).
j) Serial number(s) of the associated equipment, if applicable.
k) Deleted
l) Value(s) of the auxiliary supply, if relevant.
m) Symbol showing that some other essential information is given in a separate document
(symbol F-33).
n) Space for adjustment data (if appropriate).
o) Nominal range of use for temperature, symbolized as usage group I, II or III.

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p) Common mode voltage (note).

q) Overvoltage category (see IEC 61010-1, amendment 2, subclause 5.1.5).
r) Pollution degree according to IEC 61010-1.
s) Other required safety symbols according to IEC 61010-1.

If the markings and symbols are on an easily removable part, such as a cover, the transducer
shall have a serial number which shall also be marked on the body of the transducer.

Transducers having a non-linear relationship between input and output shall be marked with
the symbol F-33, and actual relationship between input and output shall be given in a separate
document.
NOTE To be given if there is sufficient space on the case, otherwise to be given in a separate document.

7.2 Markings relating to the reference conditions and nominal ranges of use
for transducers

7.2.1 The reference values (or ranges) and nominal ranges of use, if different from those
given in tables 3 and 4 and clause 6, shall be marked on the transducer or given in a separate
document.

7.2.2 When a reference value or a reference range is marked, it shall be identified by

underlining.

7.2.3 Table 6 shows the significance of the various markings, for example for temperature.

Table 6 – Examples of marking relating to the reference conditions

and nominal range of use for temperature

Three or four numbers shall always be used.

Example Meaning

10 ... 23 ... 35 °C Conforms to Group I

0 ... 15 ... 30 ... 45 °C Conforms to Group II
–10 ... 0 ... 45 ... 55 °C Conforms to Group III
0 ... 25 ... 40 °C Reference value: 25 °C
Nominal range of use: 0 °C to 40 °C

–5 ... 20 ... 30 ... 35 °C Reference range: 20 °C to 30 °C

Nominal range of use: –5 °C to 35 °C

7.3 Identification of connections and terminals

If so required for the correct use of the transducer, a diagram or table of connections shall be
supplied and the terminals shall be clearly marked to show the proper method of connection.

If a terminal of a measuring circuit is intended to be kept at, or near to earth (ground) potential
(for example, for safety or functional reasons), it shall either be marked with a capital N if it is
intended to be connected to the neutral conductor of an a.c. supply circuit, or it shall be marked
with symbol F-45 (see table 7) in all other circumstances.

The earthing terminal(s) shall be marked using symbol(s) F-31 and/or F-42 to F-45, as
appropriate.

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7.4 Information to be given in a separate document

The following information shall be given in the document supplied with the transducer:

– response time;
– the variation due to a magnetic field of external origin;
– the actual relationship between input and output if it is non-linear.

Table 7 – Symbols for marking transducers

No. Item Symbol

B Nature of input quantity(ies) and number of measuring circuits

B-1 D.C. circuit (for auxiliary supply only)

B-2 A.C. circuit (single phase)

B-3 D.C. and a.c. circuit

B-4 Three-phase a.c. circuit (general symbol) 3

B-6 One measuring element for three-wire network 3 1E

B-7 One measuring element for four-wire network 3N 1E

B-8 Two measuring elements for three-wire network with unbalanced load 3 2E

B-9 Two measuring elements for four-wire network with unbalanced load 3N 2E

B-10 Three measuring elements for four-wire network with unbalanced load 3N 3E

C Safety (see IEC 61010-1)

E Accuracy class

E-10 Class index (e.g. 1) when the fiducial value corresponds to the span 1
E-11 Class index (e.g. 0,5) when the fiducial value corresponds to half the span  0,5 / 0,5 
F General symbols

F-31 Earth (ground) terminal (general symbol)

F-33 Refer to a separate document

F-42 Frame or chassis terminal

F-43 Protective earth (ground) terminal

F-44 Noiseless earth (ground) terminal

F-45 Measuring circuit earth (ground) terminal

F-46 Positive terminal

F-47 Negative terminal

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Annex A
(informative)

Bibliography

IEC 60051, Direct acting indicating analogue electrical measuring instruments and their
accessories

IEC 60068-2-6:1995, Environmental testing – Part 2: Tests – Test Fc and guidance: Vibration
(sinusoidal)

IEC 60068-2-27:1987, Environmental testing – Part 2: Tests – Test Ea and guidance: Shock

IEC 60068-2-31:1969, Environmental testing – Part 2: Tests – Test Ec: Drop and topple,
primarily for equipment-type specimens

IEC 60381-1:1982, Analogue signals for process control systems – Part 1: Direct current
signals

___________

30
(Continued from second cover)

International Standard Corresponding Indian Standard Degree of Equivalence

IEC 60521 : 1988 Class 0.5, 1 and 2 IS 13010 : 2002 ac Watthour meters, Technically Equivalent
alternating-current watt-hour meters Class 0.5, 1 and 2 — Specification
IEC 61010-1 : 2001 Safety IS 9249 (Part 1) : 2010/IEC 61010-1 Identical
requirements for electrical Safety requirements for electrical
equipment for measurement, control equipment for measurement, control
and laboratory use — Part 1: General and laboratory use: Part 1 General
requirements requirements (under printing)

In addition to the above the Technical Committee responsible for the preparation of this standard has
reviewed the provision of the following International Standards referred to in this adopted standard
and has decided that they are acceptable for use in conjunction with this standard:
International Standard Title
IEC 60050 Chapter Electrotechnical Vocabulary (IEV). Chapter 303: Electronic measuring
303 : 1983 instruments
IEC 61000-4 Electromagnetic compatibility (EMC) — Part 4: Testing and measuring
techniques

Only the English language text the International Standard has been retained while adopting it as an
Indian Standard, and as such the page numbers given here are not the same as in IEC Standard.

For the purpose of deciding whether a particular requirement of this standard is complied with, the
final value, observed or calculated expressing the result of a test, shall be rounded off in accordance
with IS 2 : 1960 ‘Rules for rounding off numerical values (revised)’. The number of significant places
retained in the rounded off value should be the same as that of the specified value in this standard.
Bureau of Indian Standards

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Review of Indian Standards

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This Indian Standard has been developed from Doc No.: ETD 12 (6168).

Amendments Issued Since Publication

______________________________________________________________________________________
Amendment No. Date of Issue Text Affected
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________

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