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भारतीय मानक IS 13779 : 2020

Indian Standard

ए. सी. स्टै टिक वॉटआवर मीटर,

वर्ग 1 एवम 2 — विशिष्टि
(  दसू रा पनु रीक्षण )

a.c. Static Watthour Meters,

Class 1 and 2 — Specification
( Second Revision )

ICS 91.140.50

© BIS 2020

भारतीय मानक ब्रयू ो

B U R E A U O F I N D I A N S TA N D A R D S
मानक भवन, 9 बहादरु शाह ज़फर मार्ग, नई िदल्ली – 110002
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI-110002
         www.bis.gov.in  
www.standardsbis.in

December 2020  Price Group 11

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Equipment for Electrical Energy Measurement, Tariff and Load Control Sectional Committee, ETD 13

FOREWORD
This Indian standard (Second revision) has been adopted by the Bureau of Indian Standards, after the draft finalized
by the Equipment for Electrical Measurement, Tariff and Load Control Sectional Committee and approved by the
Electrotechnical Division Council.
This Indian Standard covers the general requirements and tests for various types of ac static watt-hour meters of
class 1 and 2. General requirements and test applicable to transformer operated meters of class 0.2 S, 0.5 S and
1.0 S with performance levels attainable in such meters have been covered in a separate Indian Standard, i.e.
IS 14697.
This standard was first published in 1993 and subsequently it was revised in 1999. Later on five amendments were
issued. This revision has been bought out to integrate all amendments and update some requirements.
The test levels as specified in this standard are regarded as minimum values to guarantee the proper function of
the meter under normal working conditions. For special applications other test levels might be necessary and have
to be fixed between the user and the manufacturer.
New tests have been added in respect of electromagnetic compatibility (EMC) for which relevant part and section
of IEC 61000/IS 14700 series may be referred. Some of the test requirements have been revised in line with
requirement given in IEC 62052-11 : 2003 and its amendment 1.
The reliability aspect is not covered in this standard as there are no short time test procedures available which
would fit in the type test to substantially check this requirement. Also influence of various harmonics and suitable
test procedures to determine such influence, require detailed consideration for specifying such requirement.
While preparing this standard assistance have been mainly derived from following publications:
IEC 62052-11 : 2003 Electricity metering equipment (a.c.) — General requirements, tests and test
conditions – Part 11 Metering equipment and its amendment 1.
IEC 62053-21 : 2003 Electricity metering equipment (a.c.) — Particular requirements — Part 21:
Static meters for active energy (classes 1 and 2) and its amendment 1.

This standard is for type testing and general requirements of electricity meters (normal meters), being used
indoors and outdoors in large quantities. It does not deal with special implementations (such as metering-part and
or displays in separate housings).
This standard distinguishes between meters intended to be used indoors and outdoors.
The composition of the Committee, responsible for the formulation of this standard is given at Annex J.
For 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 or analysis 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 same as that of the specified value in this standard.
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IS 13779 : 2020

Indian Standard
a.c. STATIC WATTHOUR METERS,
CLASS 1 AND 2 — SPECIFICATION
( Second Revision )

1 SCOPE 3.1.2 Static Watt Hour Meter

A watthour meter in which current and voltage act on
1.1 This standard specifies static watt-hour meters
solid state (electronic) elements to produce an output
of accuracy class 1 and 2, for the measurement of
proportional to watthours.
alternating-current electrical active energy of frequency
in the range 45Hz to 55Hz for single phase and three 3.1.3 Multi-rate Meter
phase balanced and unbalanced loads. It applies to their
A watthour meter provided with a number of registers,
type tests, routine tests and acceptance tests.
each operative at specified time intervals corresponding
1.2 It applies only to static watt-hour meters consisting to different tariffs.
of measuring element(s) and register(s) enclosed
3.1.4 Meter Type
together in the meter case. It also applies to operation
indicator(s) and test output(s). It also applies to Designation used for defining a particular design of
multi-rate tariff meters and meters which measure meter manufactured by one manufacturer, having:
energy in both directions and intended for indoor and a) Similar metrological properties;
outdoor application. For meters with smart functions,
b) The same principle of operation and uniform
refer IS 16444 (Part 1).
construction of parts determining these properties;
1.3 It does not apply to: and
a) Watt-hour meters, where the voltage across the c) The same ratio of the rated maximum current to
connection terminal exceeds 600 V (line to line the basic current.
voltage for meters for polyphase systems); The type may have several values of basic current and
b) Portable meters; and several values of reference voltage. These meters are
designated by the manufacturer by one or more groups
c) Data interfaces to the register of the meters.
of letters or numbers or of a combination of letters and
1.4 For rack-mounted meters, the mechanical numbers. Each type has one designation only.
requirements are not covered in this standard. NOTE — The type is represented by the sample meter(s) intended
for the type tests and whose characteristics (basic current and
2 REFERENCES reference voltage) are chosen from the values proposed by the
manufacturer.
The standards listed in Annex A contain provisions
which, through reference in this text, constitute 3.2 Terms Related to Functional Elements
provisions of this standard. At the time of publication,
3.2.1 Measuring Element
the editions indicated were valid. All standards are
subject to revision, and parties to agreements based Part of the meter which produces an output proportional
on this standard are encouraged to investigate the to the energy.
possibility of applying the most recent editions of the
3.2.2 Output Devices
standards indicated in Annex A.
3.2.2.1 Test output
3 TERMINOLOGY
A device at which output from the measuring element is
For the purpose of this standard, the following available for testing of the meter. The output may be in
definitions shall apply. the form of pulses or high resolution register.
3.1 General 3.2.2.2 Operation indicator
3.1.1 Watthour Meter (Active Energy Meter) A device which gives a visible signal of the operation
of the meter. The test output may also act as operation
An instrument which measures and registers active
indicator.
energy in watthours or in suitable multiples thereof, by
integrating active power with respect to time.

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IS 13779 : 2020

3.2.3 Memory 3.3.3 Meter Base

An element which stores digital information in a The back of the meter by which it is generally fixed
structured manner for subsequent retrieval whenever and to which are attached the measuring element, the
addressed. terminals or the terminal block, and the cover. For a
flush-mounted meter, the meter base may include the
3.2.4 Non-Volatile Memory (NVM) sides of the case.
A memory which can retain stored information in the
absence of power. 3.3.4 Meter Cover
NOTE — Memory chip with internal battery needing no The enclosure on the front of the meter, made either
replacement during the life time of meter may be considered as wholly of transparent material or opaque material
non-volatile memory, but memory with external battery shall provided with windows(s) through which the operation
not be considered as NVM. indicator (if fitted) and the display can be read.
3.2.5 Display 3.3.5 Meter Case
A device which visibly displays the contents of (a) This comprises the base and the cover.
memory (ies).
3.3.6 Accessible Conducting Part
3.2.6 Register
A conducting part which can be touched by the standard
An electromechanical or electronic device comprising test finger, when the meter is installed ready for use
both memory and display which stores and displays (see IS 1401).
information. A single display may be used with multiple
electronic memories to form multiple registers. 3.3.7 Protective Earth Terminal
3.2.7 Current Circuit The terminal connected to accessible conducting parts
of a meter, for safety purposes.
The internal connections of the meter and part of the
measuring element through which flows the current of 3.3.8 Terminal Block
the circuit to which the meter is connected. A support made of insulating material on which all or
3.2.8 Voltage Circuit some of the terminals of the meter are grouped together.
The internal connections of the meter, part of the 3.3.9 Terminal Cover
measuring element and power supply to the meter, A cover which covers the meter terminals and generally
supplied from the voltage of the circuit to which the the ends of the external wires or cables connected to the
meter is connected. terminals.
3.2.9 Auxiliary Circuit 3.3.10 Clearance
The elements (lamps, contacts, etc.) and connections of The shortest distance measured in air between two
an auxiliary device within the meter case intended to conductive parts.
be connected to an external device, for example clock,
relay, impulse counter. 3.3.11 Creepage Distance
The shortest distance measured over the surface of
3.2.10 Meter Constant insulation between two conductive parts.
Constant expressing the relation between the energy
registered by the meter and the corresponding pulse 3.4 Terms Related to Insulation
count of the test output. This is generally expressed 3.4.1 Basic Insulation
either as pulse count per watthour or pulse count
per kilo watthour (imp/kWh) or watthour per pulse The insulation applied to live parts to provide basic
(Wh/imp). This definition is not applicable for meters protection against electric shock.
having high resolution registers. NOTE — Basic insulation does not necessarily include insulation
used exclusively for functional purposes.
3.3 Terms Related to Mechanical Elements
3.4.2 Supplementary Insulation
3.3.1 Indoor Meter An independent insulation applied in addition to the
A meter which can only be used in areas which have basic insulation, in order to provide protection against
additional protection against environmental influences electric shock in the event of a failure of the basic
(in-house, enclosures and cabinets). insulation.
3.3.2 Outdoor Meter 3.4.3 Double Insulation
A meter which can be used without additional An insulation comprising both, basic insulation and
protection in an exposed outdoor environment. supplementary insulation.
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IS 13779 : 2020

3.4.4 Reinforced Insulation carried out under identical conditions, arising out of
A single insulation system applied to live parts, which factors other than measurement uncertainties.
provides a degree of protection against electric shock It is generally measured by standard deviation of
equivalent to double insulation. sufficiently large number of test data. It may also be
NOTE — The term ‘insulation system’ does not imply that the measured by dispersion of such data under limited
insulation must be one homogenous piece. It may comprise condition when sufficiently large data is not available.
several layers which cannot be tested singly as supplementary
or basic insulation. 3.5.8 Starting Current
3.4.5 Insulating Encased Meter The lowest value of current at which the meter starts
and continues to register.
A meter with case of insulating material in which
protection against electric shock does not rely on 3.6 Terms Related to influence Quantities
basic insulation only, but in which additional safety
precautions, such as double insulation of reinforced 3.6.1 Influence Quantity or Influence Factor
insulation, are provided. There being no provision for Any quantity, generally external to the meter, which
protective earth or reliance upon installation conditions. may affect its working performance.
3.5 Terms Related to Meter Quantities 3.6.2 Reference Conditions
3.5.1 Basic Current (Ib) The appropriate set of influence quantities and
performance characteristics, with reference values,
The value of current in accordance with which the their tolerances and reference ranges, with respect to
relevant performance of the meter is fixed. which the intrinsic error is specified.
3.5.2 Rated Maximum Current (Imax) 3.6.3 Variation of Error Due to an Influence Quantity
The highest value of current at which the meter purports The difference between the percentage errors of the
to meet the accuracy requirements of this standard, meter when only one influence quantity assumes
when this current flows continuously in the meter. successively two specified values, one of them being
3.5.3 Reference Voltage the reference value.
The value of voltage in accordance with which the 3.6.4 Distortion Factor
relevant performance of the meter is fixed. The ratio of the r.m.s. value of the harmonic content
3.5.4 Reference Frequency (obtained by subtracting from a non-sinusoidal
The value of frequency is accordance with which the alternating quantity, its fundamental component) to
relevant performance of the meter is fixed. the r.m.s. value of the non-sinusoidal quantity. The
distortion factor is usually expressed in percentage.
3.5.5 Class Index
3.6.5 Electromagnetic Disturbance
A number which gives the limits of the permissible
percentage error, for all values of current between Conducted or radiated electromagnetic effects which
0.1 Ib and Imax for unity power factor (and in the case may interfere functionally or metrologically with the
of polyphase meters with balanced loads) when the operation of the meter.
meter is tested under reference conditions (including 3.6.6 Reference Temperature
permitted tolerances on the reference values) as defined
in this standard. The ambient temperature specified for reference
conditions.
3.5.6 Percentage Error
3.6.6.1 Mean temperature coefficient
The percentage error is given by the following formula:
The ratio of the variation of the percentage error to
( Energy registered by the meter − true energy ) the change of the temperature which produces this
Percentage error × 100
True energy
variation.
NOTE — Since the true value cannot be determined, it is
approximated by a value with a stated uncertainty that can
3.6.7 Operating Conditions
be traced to IS 12346 or standards agreed upon between A set of specified measuring ranges for performance
manufacturer and user. characteristics and specified operating ranges for
3.5.7 Repeatability of Error influence quantities, within which the variations
in percentage errors of a meter are specified and
Repeatability of error is the degree of closeness of determined.
agreement between results of successive error for tests

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IS 13779 : 2020

3.6.8 Specified Measuring Range 5 RATINGS

The set of values of a measured quantity for which the
5.1 Standard Reference Voltages
percentage errors of a meter is intended to lie within
specified limits. The reference voltage shall be as given in Table 1
(see IS 12360).
3.6.9 Specified Operating Range
Table 1 Standard Reference Voltages
A range of values of a single influence quantity which
( Clause 5.1 )
forms a part of the operating conditions.
Meters for Standard Reference Exceptional
3.6.10 Limit Range of Operation (Limiting Conditions) Voltage (V) Calues (V)
The extreme conditions which an operating meter can (1) (2) (3)
withstand without damage and without degradation of Connection through 63.5 (110) 57.7 (100), 100
its metrological characteristics when it is subsequently voltage transformer (173)
operated under its operating conditions. Direct connection 240 (415) 220 (380),
and through current 230 (400),
3.6.11 Storage and Transport Conditions transformer only 250 (433)
The extreme conditions which a non-operating
meter can withstand without damage and without 5.2 Standard Basic Currents
degradation of its metrological characteristics when it The basic currents shall be as given in Table 2.
is subsequently operated under its operating conditions. Table 2 Standard Basic currents
3.6.12 Normal Working position ( Table 5.2 )
The position of the meter defined by the manufacturer Meters for Basic Currents (A)
for normal service. (1) (2)
For direct connection
3.6.13 Thermal Stability
1-phase 2.5, 5, 10, 15, 20
Thermal stability is considered to be reached when the 3- phase 5, 10, 15, 20, 30, 40, 50
change in error as consequence of thermal effects during Connection through current 1, 5
20 min is less than 0.1 times the maximum permissible transformer (s)
error for the measurement under consideration.
5.3 Rated Maximum Current
3.7 Terms Related to Tests
The maximum current for direct connected meters shall
3.7.1 Type Tests preferably be an integral multiple of the basic current
(for example four time of basic current).
Series of tests carried out on one meter or a small
number of meters of the same type having identical When the meter is operated from current transformer(s),
characteristics, selected by manufacturer to prove attention is drawn to the need to match the current range
conformity with all the requirements of this standard of the meter in relation to that of the secondary of the
for the relevant class of meter. These are intended to current transformer(s). The rated maximum current of
prove the general qualities and design of a given type the meter is 1.2, 1.5 or 2 time of basic current.
of meter. Typical values of rated maximum current as a
percentage of the basic current are shown in Table 3.
3.7.2 Routine Tests
Table 3 Typical Rated Maximum Current
Tests carried out on each meter to check conformity
with the requirements of this standard in aspects which ( Clause 5.3 )
are likely to vary during production. Meters (1-Phase and 3-Phase) for Rated Maximum Current
as Percentage of Basic
3.7.3 Acceptance Test Current (A)
Tests carried out on samples taken from a lot for the (1) (2)
purpose of acceptance of the lot. Direct connection 200, 300, 400, 500, 600,
800, 1000
NOTE — However specific qualities and design of the meters
in a lot can be conclusively proved by performing relevant type Connection through current 120, 150, 200
test(s) on a number of samples if agreed by the user and the transformer (s)
supplier. NOTE — The current transformer operated meters with rated
maximum current of 2 times of basic current, cover and are
4 CLASSIFICATION suitable for meters of rated maximum current of 1.2 and
1.5 times of basic current also. For requirements higher than
Meters are classified according to their respective class 2 times of basic current should be the subject of purchase
indices, for example, 1 or 2. contract.

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IS 13779 : 2020

5.4 Standard Frequency The material of which the terminal block is made
Standard value for reference frequency is 50 Hz. shall be capable of passing the tests given in
IS 13360 (Part 6/Sec 17) for a temperature of 135 °C
6 GENERAL AND CONSTRUCTIONAL and a pressure of 1.8 MPa (Method  A).
REQUIREMENTS The holes in the insulating material which form an
extension of the terminal holes shall be of sufficient size
6.1 General to also accommodate the insulation of the conductors.
Meters shall be designed and constructed in such a way The manner of fixing the conductors to the terminals
as to avoid introducing any danger in normal use and shall ensure adequate and durable contact such that
under normal conditions, so as to ensure especially: there is no risk of loosening or undue heating. Screw
a) Personal safety against electric shock; connections transmitting contact force and screw
b) Personal safety against effects of excessive fixings which may be loosened and tightened several
temperature; times during the life of the meter shall screw into a
metal nut.
c) Safety against spread of fire; and
All parts of each terminal shall be such that the risk of
d) Protection against solid objects, dust and water.
corrosion resulting from contact with any other metal
All parts which are subject to corrosion under normal part is minimized.
conditions shall be effectively protected. Any protective
coating shall not be liable to damage by ordinary The current circuit connections can be terminated or
handling nor damage due to exposure to air, used under guided through the measuring element of meter. The
normal working conditions. cable/conductor in such a design shall be held firmly
in position by suitable guiding and fixing arrangement
NOTE — For meters for special use in corrosive atmosphere,
and that contact pressure is not transmitted through
additional requirements shall be fixed in the purchase contract
(for example, salt mist test).
insulating material. For current circuits, the voltage
is considered to be the same as for the related voltage
6.2 Meter Case circuit.
The meter shall have a reasonably dust/moisture-proof The voltage circuit connection can be directly
case, which shall be sealed by the manufacturer in such terminated on a suitable terminal arrangement or
a way that the internal parts of the meter are accessible tapped by suitable arrangement which shall not cause
only after breaking such distinctive seal(s). burnouts and corrosion due to outdoor usage.
The cover shall not be removable without the use of a Terminals with different potentials which are grouped
tool. close together shall be protected against accidental
The case shall be so constructed and arranged that short-circuiting. Protection may be obtained by
any non-permanent deformation cannot prevent the insulating barriers. Terminals of one current circuit are
satisfactory operation of the meter. considered to be at the same potential.
Unless otherwise specified, the meters having a case The terminals, the conductor fixing screws, or the
wholly or partially made of metal, shall be provided external or internal conductors shall not be liable to
with a protective earth terminal. come in to contact with terminal covers (if made of
metals).
6.3 Window The protective earth terminal, if any:
If the cover is not transparent one or more windows shall a) Shall be electrically bonded to the accessible
be provided for reading the displays and observation of metal parts;
the operation indicator, if fitted. These windows shall
be covered by toughened transparent material which b) Should, if possible, form part of meter base;
cannot be removed undamaged without breaking the c) Should preferably be located adjacent to its
seal(s). terminal block;
d) Shall accommodate a conductor having a cross
6.4 Terminals, Terminals Block(s) and Protective
section at least equivalent to the main current
Earth Terminal
conductors but with a lower limit of 6 mm2 and
Terminals may be grouped in (a) terminal block(s) an upper limit of 16 mm2 (for copper conductors);
having adequate insulating properties and mechanical and
strength. In order to satisfy such requirements when e) Shall be clearly identified by the earthing symbol.
choosing insulating materials for the terminal block(s),
adequate testing of materials should be taken into After installation, it shall not be possible to loosen the
account. protective earth terminal without the use of a tool.

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IS 13779 : 2020

6.5 Terminal Cover(s) Table 4b Clearance and Creepage Distance for

Every terminal block shall be provided with a terminal Outdoor Meter
cover conforming to 6.5.1 or 6.5.2. ( Clause 6.6 )
6.5.1 Short Terminal Cover Sl Voltage Phase-to-Earth Minimum Minimum
No. Derived from Rated Clearances Creepage
The terminals, their fixing screws and the insulated System Voltages (mm) Distance (mm)
compartment housing them shall be enclosed by a cover (V)
with a provision for sealing. The cover may be of the
(1) (2) (3) (4)
same size as that of the terminal block. The wiring with
this type of cover may be carried out from the front of i) Not exceeding 100 1.5 3.2
the meter board. ii) Not exceeding 150 3.0 5.0
iii) Not exceeding 300 5.5 10.0
6.5.2 Extended Terminal Cover
iv) Not exceeding 600 8.0 20.0
The terminals, their fixing screws, a suitable length of
external insulated conductor and its insulation shall be 6.7 Insulating Encased Meter
enclosed by a cover with a provision for sealing. The
A meter having a durable and substantially continuous
wiring with this type of cover shall be carried out from
enclosure made wholly of insulating material, including
the rear of the meter board.
the terminal cover, which envelops all metal parts with
The fixing screws used on the terminal cover for fixing the exception of small parts, for example, name-plate
and sealing in 6.5.1 and 6.5.2 shall be held captive in screws, suspensions and rivets. If such small parts are
the terminal cover. accessible by the standard test finger (see IS 1401) from
When the meter is mounted on the meter board, no outside the case, then they shall be additionally isolated
access to the terminals shall be possible without from live parts by supplementary insulation against
breaking seal(s) of the terminal cover. failure of basic insulation or loosening of live parts.
The insulating properties of lacquer, enamel, ordinary
6.6 Clearance and Creepage Distance paper, cotton, oxide film on metal parts, adhesive film
The clearance and creepage distances of the terminal and sealing compound, or similar unsure materials,
block and those between the terminals and the shall not be regarded as sufficient for supplementary
surrounding parts of the metal enclosure shall be not insulation.
less than the value specified in Table 4a Table 4b. For the terminal block and the terminal cover of such a
The clearance between the terminal cover, if made meter, reinforced insulation is sufficient.
of metal, and the upper surface of the screws when
6.8 Resistance to Heat and Fire
screwed down to the maximum applicable conductor
fitted shall be not less than the relevant values indicated The terminal block, the terminal cover and the meter
in Table 4a and Table 4b. case shall ensure reasonable safety against spread of
fire. They should not be ignited by thermic overload of
The requirements of the impulse voltage test shall also
live parts in contact with them. To comply therewith it
be met (see 12.7.6.2).
must fulfil the tests as specified in 12.4.
Table 4a Clearance and Creepage Distances for
Indoor Meter 6.9 Protection against Penetration of Dust and
Water
( Clause 6.6 )
The meter shall conform to the degree of protection as
Sl Voltage Phase-to-Earth Minimum Minimum given below:
No. Derived from Rated Clearances Creepage
System Voltages (V) (mm) Distance (mm) IP 51 for indoor meter and IP 54 for outdoor meter, but
(1) (2) (3) (4) without suction in meter.
i) Not exceeding 100 0.8 1.4 6.10 Display of Measured Values
ii) Not exceeding 150 1.5 1.6 The information can be shown either with an
iii) Not exceeding 300 3.0 3.2 electromechanical register or an electronic display.
iv) Not exceeding 600 5.5 6.3 In case of an electronic display, the corresponding

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IS 13779 : 2020

non-volatile memory shall have a minimum retention the cover, the number is to be marked also on the
time of 5 years. Manufacturer shall declare the retention meter base or displayed;
time. e) The reference voltage in one of the following
NOTE — Longer retention time of the non-voltaic memory forms:
should be the subject of purchase contract. The number of elements if more than one, and
In the case of multiple values presented by a single the voltage at the meter terminals of the voltage
display, it must be possible to display the contents of circuit(s).
all relevant memories. When displaying the memory, 1) The nominal voltage of the system or
identification of each tariff/parameter shall be available. the secondary voltage of the instrument
The current tariff shall be indicated. When the meter is transformer to which the meter is intended to
not energised; the electronic display need not be visible. be connected.
The principal unit for the measured values shall be kilo 2) Examples of voltage markings are shown in
watthour (kWh) or the mega watthour (MWh). Table 5.
The register shall be able to record and display starting f) Principal unit in which the meter reads, for
from zero, for a minimum of 1 500 h, the energy example, kWh.
corresponding to rated maximum current at reference g) The rated secondary current of the transformer(s)
voltage and unity power-factor. Register should not to which the meter should be connected, for
rollover in between this duration. example, –/5 A: the basic current and the rated
NOTE— Values higher than 1500 h should be the subject of maximum current of the meter may be included in
purchase contract. the type designation.
Examples of current markings are shown in Table 6.
6.11 Output Device
Table 5 Voltage Markings
The meter shall have a test output accessible from the
front and be capable of being monitored with suitable [ Clause 7.1 (e) ]
testing equipment. The operation indicator, if fitted, Type of Meter Method of Marking Example
must be visible from the front.
(1) (2) (3)
Since the sequence of test output pulses may not 1- phase, 2-wire Voltage between line 240 V
be homogeneous, the manufacturer shall state the and neutral
minimum number of pulse counts necessary to ensure 3-phase, 3-wire 2 × Voltage between 2 × 110V
that the error contribution due to such non-homogeneity lines
does not exceed 1/10th of the specified error limits at 3-phase, 4-wire 3 × Voltage between 3 × 110/√3 V, 3 × 240
various points and consistent with desired resolution. line and neutral V or 3 × 63.5V

The resolution of the test output in the form of pulses Table 6 Current Markings
or high resolution register, whether accessible on the
[ Clause 7.1 (g) ]
meter through external display, shall be sufficient to
conduct satisfactorily accuracy test at the lowest load in Type of Meter Method of Example
less than 5 min and starting current test in less than 10 Marking
min. Additional high resolution register with minimum (1) (2) (3)
decimal of two digits shall also be available in the 1-phase , whole current, Basic current and 10-20 A
meter for testing purpose as mentioned in this standard. Ib 10 A, Imax 20 A rated maximum
current
7 MARKING OF METERS 1-phase, transformer operated, Basic current and –/1(1.2) A
Ib 1A, Imax 1.2 A rated maximum
current
7.1 Name Plate
3-phase, whole current, Basic current and 50 – 60 A
Every meter shall bear the following information: Ib 50 A, Imax 60 A rated maximum
current
a) Manufacturer’s name and/or trade mark and the
3-phase, transformer operated, Basic current and -/5 (6) A
place of manufacture; Ib –/5A, Imax 6 A rated maximum
b) Designation of type (see 3.1.4) and, if required, current
space for approval mark; h) The reference frequency in Hz;
c) The number of phases and the number of wires for j) The meter constant, for example in the form; X
which the meter is suitable (for example, single Wh/imp or X imp/kWh;
phase 2 wire, three phase 3 wire, three phase 4
k) The class index of the meter;
wire). These markings may be replaced by the
graphical symbols (as per IS 12032 series); m) The reference temperature if different from 27 °C;
d) The serial number and year of manufacture. If n) The sign of double square for insulating encased
the serial number is marked on a plate fixed to meters; and

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IS 13779 : 2020

p) Country of manufacture. NOTE — For special applications, other temperature values

can be used according to agreement between manufacturer and
Information under (a), (b), (c) and (p) may be marked purchaser.
on an external plate permanently attached to the meter
cover. 8.2 Relative Humidity
The information (d) to (k) shall be marked on a name The meter shall meet the relative humidity requirements
plate preferably placed within the meter. of Table 8. For combined temperature and humidity
The marking shall be indelible, distinct and readable test, see 12.6.3.
from outside the meter. Table 8 Relative Humidity
If the meter registers energy through instrument ( Clause 8.2 )
transformer(s), which are accounted in the meter
constant, the transformation ratio(s) shall be marked. Annual mean < 75 percent
For 30 days, these days being spread in a natural <95 percent
Standard symbols shall be used (see IS 12032 series). manner over the year
occasionally on other days <85 percent
7.1.1 BIS Certification Marking
The product(s) conforming to the requirements of The limits of relative humidity as a function of ambient
this standard may be certified as per the conformity temperature are shown in Annex B. The graph may
assessment schemes under the provisions of the be modified in line with meteorological conditions
Bureau of Indian Standards Act, 2016 and the Rules prevalent in the place of use.
and Regulations framed thereunder, and the products
may be marked with the Standard Mark. 9 ELECTRICAL REQUIREMENTS

7.2 Connections, Diagrams and Terminal Marking 9.1 Power Consumption

Every meter shall be indelibly marked with a diagram 9.1.1 Power Consumption in Voltage Circuit
of connections. For poly-phase meters, this diagram
shall also show the phase sequence for which the meter The Active and apparent power consumption in each
is intended. It is permissible to indicate the connection voltage circuit of a meter at reference voltage, reference
diagram by an identification figure in accordance with temperature and reference frequency shall not exceed
relevant standards. the values shown in Table 9.
If the meter terminals are marked, this marking shall Table 9 Power Consumption in Voltage Circuit
appear on the diagram. including the Power supply
When a number of meters are connected to single ( Clause 9.1.1 )
distributing mains for registering electricity supplied
Meters Class of Meters
to different consumer loads, separate service (1 and 2 )
lines-phase(s) and neutral, shall be used for each meter. Single phase and polyphase (per phase) 1.5 W and 10 VA
Moreover, interconnection of phases or neutrals of such
loads connected to different meters must be avoided. NOTES
Each independently metered consumer load must be 1 The above figures are mean values. Switching power supplies
directly connected to distributing mains through its with peak values in excess of these are permitted but attention
meter connected in specified phase sequence so as to should be paid to the rating of associated voltage transformers.
meet accuracy requirements of this standard. 2 In case additional features like remote metering etc. is built
into the meter then additional loss may be agreed between
Standard connection diagram are shown in Annex H. supplier and purchaser.

8 CLIMATIC CONDITIONS 9.1.2 Power Consumption in Current Circuit

The apparent power taken by each current circuit for
8.1 Temperature Range
at basic current, reference frequency and reference
Temperature range of the meter shall be as indicated in temperature shall not exceed the value shown in
Table 7. Table 10.

Table 7 Temperature Range

( Clause 8.1 )
Sl No. Parameter Temperature range for Indoor Meter Temperature range for Outdoor Meter
(1) (2) (3) (4)
i) Specified operating range 0 °C to + 55 °C – 10 °C to + 55 °C
ii) Limit range of storage and transport – 25 °C to + 70 °C – 25 °C to + 70 °C

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IS 13779 : 2020

Table 10 Apparent Power Consumption in Table 12 Variations Due to Short-time

Current Circuit Over Currents
( Clause 9.1.2 ) ( Clause 9.2.3 )
Meters for Value of Power Limits of Variation
Meters for Class of Meters
Current Factor in Percentage Error
(1) (2) for Meters of Class
Direct connection single phase and 4.0 VA 2.5 VA 1 2
polyphase (per phase)
Direct connection Ib 1 1.5 1.5
Connection through current transformers 4.0 VA 2.5 VA
Connection through Ib 1 0.5 1.0
Single phase and polyphase (per phase)
Current transformer

NOTE — The apparent power consumption in current circuit

For testing, see 12.7.3.
shall not be applicable for meters where load current carrying
conductors are not terminated at the meter and are guided 9.3 Influence of Self-heating
through current measuring sensors.
The variation in percentage error due to self-heating
9.2 Influence of Supply Voltage shall not exceed the values given in Table 13.
9.2.1 Voltage Range Table 13 Variation in Percentage Error
Voltage range shall be as given in Table 11. due to Self-Heating

Table 11 Voltage Range ( Clause 9.3 )

( Clause 9.2.1 ) Value of Power Limits of Variation in Percentage

Current Factor Error for Meters of Class
Specified operating range 0.80 to 1.1Vref 1 2
Limit range of operation 0.70 to 1.2Vref Imax 1 0.7 1.0
NOTES Imax 0.5 lagging 1.0 1.5
1 For the permissible error due to voltage variation
(see Table 17). For testing, see 12.7.4.
2 Extended operating ranges will be the subject of purchase
contract. 9.4 Influence of Heating
Under normal conditions of use, electrical circuits
9.2.2 Voltage Dips and Interruptions
and insulation shall not reach a temperature which
Voltage dips and interruptions shall not produce a might adversely affect the operation of the meter. The
change in the register of more than 0.01 kWh and the temperature rise at any point of the external surface of
test output shall not produce a signal equivalent to more the meter shall not exceed by more than 20 °C with an
than 0.01 kWh. These values are based on rated current ambient temperature between 25 °C to 45 °C.
of 5A and 100 V of the meter. For other voltage and
For testing, see 12.7.5. Visual inspection for
current ratings, the value 0.01 kWh has to be converted
deformation, if any of the meter including terminal
accordingly. When the voltage is restored, the meter
blocks is to be carried out. There shall be no deformation.
shall not have suffered degradation of its metrological
Connecting cables during the test shall be of ratings not
characteristics.
less than the test current.
For testing, see 12.7.2.
9.5 Insulation
9.2.3 Short Time Over Current
The meter and its incorporated auxiliary devices, if
Short-time over current shall not damage the meter. The any, shall be such that they retain adequate dielectric
meter shall perform correctly, when back to its initial qualities under normal conditions of use, taking into
working conditions and the variation of error shall not account of the atmospheric influences and different
exceed the values shown in Table 12. voltages, to which they are subjected under normal
a) Meter for direct connection. conditions of use.
The meter shall be able to carry a short time over The meter shall withstand the impulse voltage test and
current of 30 Imax with tolerance of –10 percent and the ac voltage test as specified in 12.7.6.
+ 0 percent, for one half-cycle at rated frequency.
9.6 Immunity to Earth/Phase Fault
b) Meter for connection through current transformer.
This test applies to three-phase four wire meters.
The meter shall be able to carry for 0.5 second a
current equal to 20 times the maximum current During test under a simulated earth/phase fault
with tolerance of +0 to –10 percent. condition in one/two of the three lines, all voltages
are increased to 1.1 times the nominal voltages during

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IS 13779 : 2020

4 h. The neutral terminal of the meter under test is b) Electromagnetic HF field;

disconnected from the neutral terminal of the meter c) Fast transient burst; and
test equipment (MTE) and is connected to the MTE’s d) Surge immunity test.
line at which the earth/phase fault has to be simulated For testing, see 12.9.
(see Annex E).
10.2 Radio Interference Suppression
In this way, the two voltage elements of the meter under
test which are not affected by the earth/phase fault are The meter shall not generate conducted or radiated
connected to 1.9 times the nominal phase voltages. noise which could interfere with other equipment.
During this test the current circuits are set to 50 percent For testing, see 12.9.6.
of the rated Ib, power factor 1 and symmetrical load.
After the test, the meter shall show no damage and shall 11 ACCURACY REQUIREMENTS
operate correctly.
The change of error measured when the meter is back 11.1 Limits of Error Due to Variation of the Current
at nominal working temperature shall not exceed the When the meter is under the reference conditions
limits given in Table 14. For testing, see 12.8. given in 12.10.1, the percentage error shall not exceed
Table 14 Change of Error due to the limits for the relevant accuracy class given in
Earth/Phase Fault Tables 15 and 16.

( Clause 9.6 ) If the meter is designed for the measurement of energy

in both directions, the values in Table 15 and 16 shall
Value of Power Limits of Variation in Percentage apply for each direction.
Current Factor Error for Meters of Class
The difference between the percentage error when the
1 2
meter is carrying a single-phase load at basic current
(1) (2) (3) (4) and unity power factor and the percentage error when
Ib 1 0.7 1.0 the meter is carrying balance polyphase load at basic
current and unity power factor, shall not exceed 1.5 and
10 ELECTROMAGNETIC COMPATIBILITY 2.5 for meters of classes 1 and 2 respectively.
(EMC) NOTE — When testing for compliance with Table 16, the test
current shall be applied to each element, in sequence.
10.1 Immunity to Electromagnetic Disturbance
11.2 Limits of Error due to Other Influence
The meter shall be designed in such a way that Quantities
conducted or radiated electromagnetic disturbance
as well as electrostatic discharge do not damage nor Limits of variation in percentage error due to the
substantially influence meter. change of influence quantities with respect to reference
conditions, as given in 12.10.1, shall not exceed the
NOTE — The disturbances to be considered are:
limits for the relevant accuracy class given in Table 17.
a) Electrostatic discharge;

Table 15 Percentage Error Limits

(Single-Phase Meters and Polyphase Meters with Balanced Loads)
( Clause 11.1 )
Sl. No. Value of Current Power Percentage Error Limits for
Factor Meters of Class
For direct connected meters For transformer operated meters 1 2
(1) (2) (3) (4) (5) (6)
i) 0.05 Ib ≤ I < 0.1 Ib 0.02 Ib ≤ I < 0.05 Ib 1 ± 1.5 ± 2.5
ii) 0.1 Ib ≤ I ≤ Imax 0.05 Ib ≤ I ≤ Imax 1 ± 1.0 ± 2.0
iii) 0.1 Ib ≤ I < 0.2 Ib 0.05 Ib ≤ I < 0.1 Ib 0.5 lagging ± 1.5 ± 2.5
0.8 leading ± 1.5 –
iv) 0.2 Ib ≤ I ≤ Imax 0.1 Ib ≤ I ≤ Imax 0.5 lagging ± 1.0 ± 2.0
0.8 leading ± 1.0 –
v) When specially requested by the When specially requested by the user: 0.25 lagging ± 3.5 –
user: from 0.2 Ib to Ib from 0.1 Ib to Ib 0.5 leading ± 2.5 –

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IS 13779 : 2020

Table 16 Percentage Error Limits (Polyphase Meters Carrying a Single Phase Load, But with Balanced
Polyphase Voltages Applied to Voltage Circuits)
( Clause 11.1 )
Value of Current Power Factor of Relevant Percentage Error Limits for
Element Meters of Class
For direct connected meters For transformer operated meters 1 2
(1) (2) (3) (4) (5)
0.1 Ib ≤ I ≤ Imax 0.05 Ib ≤ I ≤ Imax 1 ± 2.0 ± 3.0
0.2 Ib ≤ I ≤ Imax 0.1 Ib ≤ I ≤ Imax 0.5 lagging ± 2.0 ± 3.0

Table 17 Influence Quantities

( Clauses 9.2.1 and 11.2 )
Sl No. Influence Quantities Value of Current Power Limit of Variation in Percentage
(Balanced Unless Factor Error for Meters of Class
Otherwise Stated) 1 2
(1) (2) (3) (4) (5) (6)
i) Voltage variation ±10 percent (see Note 1) Ib 1 0.7 1.0
0.5 lagging 1.0 1.5
ii) Frequency variation ± 5 percent Ib 1 0.8 1.3
0.5 lagging 1.0 1.5
iii) Wave form: 10 percent of third harmonic in the Ib 1 0.6 0.8
current (see Note 2)
iv) Reversed phase sequence 0.1 Ib 1 1.5 1.5
v) Voltage unbalance (see Note 3) Ib 1 2.0 4.0
vi) d.c. and even harmonics in AC current circuit Refer Annex C 1 3.0 6.0
(see Note 4)
vii) Continuous magnetic induction of external origin Ib 1 2.0 3.0
(see Note 5)
viii) Magnetic induction of external origin 0.5 mT Ib 1 2.0 3.0
(see Note 6)
ix) Electromagnetic HF fields (see Note 7) Ib 1 2.0 3.0
x) Operation of accessories (see Note 8) 0.05 Ib 1 0.5 1.0
xi) Continuous ‘abnormal’ magnetic induction of Ib 1 4.0 4.0
external origin (see Note 9)
xii) ‘Abnormal’ ac magnetic induction of external origin Ib 1 4.0 4.0
10 mT (see Note 9)
xiii) Electrical fast transient burst (see Note 10) Ib 1 4.0 6.0

NOTES 4 The test conditions are given in Annex C. This test does not
1 For the voltage ranges from –20 percent to –10 percent and apply to transformer operated meters.
+10 percent to +20 percent, the limits of variation in percentage 5 The test conditions are specified in 12.11.
error are three times the values given in Table 17. 6 A magnetic induction of external origin of 0.5 mT produced
Below 0.8 Vref and upto 0.7 Vref, the said limits are five times by a current of the same frequency as that of the voltage applied
the value given in Table 17. to the meter and under the most unfavourable conditions of
Below 0.7 Vref the error of the meter may vary between phase and direction shall not cause a variation in the percentage
+10 percent and –100 percent. error of the meter exceeding the values shown in Table 17. The
test conditions are specified in 12.11.
2 The distortion factor of the voltage shall be less than
1 percent. The variation in percentage error shall be measured 7 The test conditions are specified in 12.9.3
under two conditions. The peak of third harmonic in the first 8 Such an accessory, enclosed in the meter case is energized
measurement in phase and in the second measurement in intermittently, for example, the electromagnet of a multi-rate
antiphase of the peaks of the fundamental current. register.
3 The polyphase meter shall measure and register within the 9 The test conditions are specified in 12.11. In the event of
variation in percentage error limits shown in Table 17 if one logging of abnormal magnetic induction with date and time,
or the two phases of the 3-phase network are interrupted, the positive variation may be beyond the limit of 4 percent but
provided the reference phase is available that is Y-phase for not exceeding a power value equivalent to the product of rated
3-phase 3-wire meters and neutral for 3-phase 4-wire meters. voltage and maximum current.
However, the operation of the meter shall not be affected by 10 The test conditions are specified in 12.9.4.
such removal of reference phase.

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IS 13779 : 2020

11.3 Limits of Error Due to Ambient Temperature 11.5 Starting Current

Variation The meter shall start and continue to register at the
The determination of the mean temperature coefficient current shown in Table 19.
for operating temperature range shall be made, but in
no case, the temperature shall exceed the specified 11.6 Meter Constant
operating temperature range. The whole operating Relation between the test output and the indication in
temperature range shall be divided into two subranges: the display shall comply with the marking on the name
a) lowest value of the operating temperature range to plate.
reference temperature; and It is preferable that the connection to the auxiliary pulse
b) reference temperature to maximum value of output is/are marked to indicate the correct method of
operating temperature range. connection, if these connections are made by means
of plugs and sockets, these connections should be
The mean temperature coefficients of each
irreversible.
subrange shall be determined individually by taking
measurements at lowest value of operating temperature 11.7 Repeatability of Error Test
range, reference temperature and maximum value of
Repeatability of error shall be checked at 0.05 Ib, Ib and
operating temperature range.
UPF load. Repeatability shall not exceed 0.5 percent
Each of the mean temperature coefficient shall not for class 1 and 1.0 percent for class 2 as measured by
exceed the limits given in Table 18. dispersion method. (see 12.17).
11.4 Starting and Running with No-load 12 TEST AND TEST CONDITIONS
For these tests, the conditions and the values of the
influence quantities shall be as stated in 12.10.1 except 12.1 Test Conditions
for any changes specified below. All tests are carried out under reference conditions
unless otherwise stated in the relevant clause.
11.4.1 Initial Start-up of the Meter
The meter shall be functional within five seconds after 12.2 Classification of Tests
the rated voltage is applied to meter terminals. The schedule and recommended sequence shall be as
given in Table 20. The accuracy of meter at reference
11.4.2 Running with No-Load
conditions shall remain within accuracy class after
When the voltage is applied with no current flowing in completion of any type test, irrespective of the variation
the current circuit, the test output of the meter shall not allowed during particular type test.
produce more than one output pulse count. For testing,
In case of modifications to the meter made after the
see 12.13.
type test and affecting only part of the meter, it will be
Table 18 Temperature Coefficient sufficient to perform limited tests on the characteristics
( Clause 11.3 ) that may be affected by the modification.
Value of Power Mean Temperature 12.2.1 Number of Samples and Criteria for Conformity
Current Factor 1Coefficient
44444for2Meter
4444 43
of Class
Type test shall be made on minimum one or more
1 2 samples (1st set) selected by the manufacturer and test
(1) (2) (3) (4) sequence shall be as given in Table 20. Each specimen
From 0.1 Ib to Imax 1 0.05 0.10 shall comply with all tests given in Table 20. In case
of one test sample failing to comply in any respect,
From 0.2 Ib to Imax 0.5 lagging 0.07 0.15 further same number(s) of sample(s) (equivalent to
1st set) shall be taken all of which shall comply with the
Table 19 Starting Currents requirements of standard given in Table 20.
( Clause 11.5 ) 12.2.2 Schedule of Acceptance Tests
Meters for Power Class of Meter Required tests are marked with “A” in Table 20.
1444442444443
Factor
1 2 12.2.2.1 Recommended sampling plan and criteria for
(1) (2) (3) (4) acceptance
Direct connection. Percentage 1 0.4 0.5 A recommended sampling plan and the criteria for
of basic current (Ib) acceptance of the lot are given in Annex G.
Connection through current 1 0.2 0.3
transformer. Percentage of 12.2.3 Schedule of Routine Tests
basic current (Ib) Required tests are marked with “R” in Table 20.

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IS 13779 : 2020

12.3 Test of Mechanical Requirements Sl No. Test Clause A R

Reference
12.3.1 Shock Test
(1) (2) (3) (4) (5)
The test shall be carried out as per IS 9000
3.6 Test of immunity to 12.8
(Part 7/Sec 1) under the following conditions: earth/phase fault
a) Meter in non-operating condition, without the 4 Test for 12.9
packing; Electromagnetic
Compatibility
b) Half-sine pulse;
4.1 Radio interference 12.9.6
c) Peak acceleration: 40 g (400 m/s2); and measurement
d) Duration of the pulse: 18 ms 4.2 Fast transient burst test 12.9.4
Number of shock: two in both direction of three mutual 4.3 Test of immunity to 12.9.2
perpendicular axes (Total of 12 shocks). electrostatic discharges
After the test, the meter shall show no damage or change 4.4 Test of immunity to 12.9.3
in cumulative kWh register. After the test, variation in electromagnetic HF field
percentage error shall not exceed the 50 percent of 4.5 Surge immunity test 12.9.5
accuracy class index at Ib, 0.05 Ib and Imax (at Cos θ = 1). 5 Test for Climatic 12.6
Table 20 Schedule of Type Tests Influences
5.1 Dry heat test 12.6.1
( Clauses 12.2, 12.2.2 and 12.2.3 )
5.2 Cold test 12.6.2
Sl No. Test Clause A R
Reference 5.3 Damp heat cyclic test 12.6.3

(1) (2) (3) (4) (5) 6 Test for Mechanical 12.3

Requirements
1 Test of Insulation 12.7.6
Properties 6.1 Vibration test 12.3.2

1.1 Impulse voltage test 12.7.6.2 6.2 Shock test 12.3.1

1.2 a.c. high voltage test 12.7.6.3 A R 6.3 Spring hammer test 12.3.3

1.3 Insulation test 12.7.6.4 A R 6.4 Protection against 12.5

penetration of dust and
2 Test of Accuracy 12.10 water
Requirements
6.5 Test of resistance to heat 12.4
2.1 Test on limits of error 11.1 A R and fire
2.2 Interpretation of test 12.16 A: Acceptance test R: Routine test
results
2.3 Test of meter constant 12.15 A 12.3.2 Vibration Test
2.4 Test of starting condition 12.14 A R The test shall be carried out as per IS 9000 (Part 8)
2.5 Test of no-load condition 12.13 A R under the following conditions:
2.6 Test of ambient 12.12 a) Meter in non-operation condition without the
temperature influence packing
2.7 Test of repeatability of 12.17 A b) Frequency range: 10 – 150 – 10 Hz.
error
c) Transition frequency (f): 60 ± 3 Hz.
2.8 Test of influence 12.11
quantities d) frequency below f: constant amplitude of
3 Test of Electrical 12.7
movement 0.15 mm
Requirement e) frequency above f: constant acceleration 2 g
3.1 Test of power 12.7.1 A (1g = 9.8 m/s2)
consumption test f) Single point control
3.2 Test of influence of 12.7.2 g) Number of sweep cycles per axis: 10
supply voltage
NOTE — 10 sweep cycles = 75 minutes
3.3 Test of influence short- 12.7.3
time over currents After the test the meter shall show no damage or change
in cumulative kWh register. After the test variation in
3.4 Test of influence of self- 12.7.4
heating percentage error of the meter error shall not exceed
50 percent of class index at 0.05 Ib, basic current and
3.5 Test of influence of 12.7.5
heating
maximum current (at Cos θ = 1).

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IS 13779 : 2020

12.3.3 Spring Hammer Test 12.6 Tests for Climatic Influences

The mechanical strength of the meter case shall be After each of the climatic tests, the meter shall show no
tested with a spring hammer (refer IEC 60068-2-75). damage or change in cumulative kWh register. These
The meter shall be mounted in its normal working tests should not affect the functioning of the meters.
position and the spring hammer shall act on the outer 12.6.1 Dry Heat Test
surfaces of the meter cover (including windows and on
the terminal cover with a kinetic energy of 0.22 Nm ± The test shall be carried out according to relevant
0.05 Nm. section of IS 9000 (Part 3/Sec 3). Under the following
conditions:
The result of the test is satisfactory if the meter case
a) Meter in non-operating condition
and terminal cover do not sustain damage which could
affect the function of the meter and it is not possible to b) Temperature: + 70 ± 2 °C
touch live parts. Slight damage which doesn’t impair c) Duration of the test: 72 h
the protection against indirect contact or the penetration
of solid objects, dust and water is acceptable. 12.6.2 Cold Test
The test shall be carried out according to relevant
12.4 Test of Resistance to Heat and Fire section of IS 9000 (Part 2/Sec 3) under the following
The test shall be carried out according to IS 11000 conditions:
(Part 2/Sec 1), with the following temperatures: a) Meter in non-operating condition
a) terminal block : 960 °C ± 15 °C b) Temperature: – 25 ± 3 °C
b) terminal cover and meter case: 650 °C ± 10 °C c) Duration of the test: 72 h
c) duration of application: 30 s ± 1 s. 12.6.3 Damp Heat Cycle Test
The contact with the glow wire may occur at any
The test shall be carried out according to relevant
random location. If the terminal block is integral with
section of IS 9000 (Part 5/Sec 2) under the following
the meter base, it is sufficient to carry out the test only
condition:
on the terminal block.
a) Meter in operating condition
12.5 Test of Protection Against Penetration of Dust b) Voltage and auxiliary circuits energised with
and Water reference voltage
The test shall be carried out according to IS/IEC 60529 c) Without any current in the current circuits
under the following conditions:
d) Upper temperature +40 °C ± 2 °C for indoor
a) Protection against penetration of dust meters
1) Meter in non-operating condition and mounted  +55 °C ± 2 °C for outdoor meters
on an artificial wall. e) No special precautions shall be taken regarding
2) The test should be conducted with sample the removal of surface moisture
lengths of cable (exposed and sealed) of the f) Duration of test: 6 cycles
types specified by the manufacturer and
terminal cover in place. 24 h after the end of this test the meter shall be submitted
to the following tests:
3) First characteristic digit: 5 (IP 5X).
a) An insulation resistance test according to 12.7.6.4.
Any ingress of dust only be in a quantity not
impairing the operation of the meter, and not b) A functional check.
impairing its dielectric strength (insulating strength). c) The meter shall show no damage or change in
For testing, see 12.7.6.4. cumulative kWh register.
b) Protection against penetration of water The damp heat test also serves as a corrosion test.
The result is judged visually. No trace of corrosion
1) Meter in non-operating condition
likely to affect the functional properties of the
2) Second characteristic digit: meter shall be apparent.
1 (IP X 1) for indoor meters
12.7 Test of Electrical Requirements
4 (IP X 4) for outdoor meters
Any ingress of water must only be in a quantity 12.7.1 Test of Power Consumption
not impairing the operation of the meter, and not The power consumption in the voltage and current
impairing its dielectric strength (insulating strength). circuit shall be determined at reference values of the
For testing, see 12.7.6.4 influencing quantities given in 12.10.1 by any suitable
method. The overall accuracy shall be better than
5 percent.

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IS 13779 : 2020

12.7.2 Test of Influence of Supply Voltage their thermal time constants) carrying 1.15 times the
The test shall be carried out under the following reference voltage, the temperature rise of the external
conditions: surface shall not exceed by more than 20 °C, with the
ambient temperature between 25 °C to 45 °C.
a) Meter in operating condition,
During the test, the duration of which shall be 2h, the
b) Voltage and auxiliary circuits energised with meter shall be not exposed to draught or direct solar
reference voltage, radiation.
c) Without any current in the current circuits:
After the test, the meter shall show no damage and shall
1) Voltage interruptions of Vref = 100 percent comply with the dielectric tests of 12.7.6.4.
i) Interruption time: 1 s
12.7.6 Test of Insulation Properties
ii) Number of interruptions: 3
iii) Restoring time between interruptions: 50 12.7.6.1 General test conditions
ms (see also Annex D) The test shall be carried out only on a complete meter
2) Voltage interruption of Vref = 100 percent with its cover (except when indicated hereafter) and
i) Interruption time: 20 ms terminal cover, the terminal screws being screwed
down to maximum applicable conductor fitted in the
ii) Number of interruptions: 1 (see also terminals. Test procedure shall be in accordance with
Annex D) IS 2071 (Part 1).
3) Voltage dips of Vref = 50 percent
The impulse voltage tests shall be carried out first and
i) Dip time: 1 min the a.c. high voltage tests afterwards.
ii) Number of dips: 1 (see also Annex D) During type tests, the dielectric property tests are
For requirement, see 9.2.2 considered to be valid only for the terminal arrangement
of the meter which has undergone the tests. When the
12.7.3 Test of Influence of Short Time Over Currents terminal arrangements differ, all the dielectric property
The test circuit shall be practically non-inductive. tests shall be carried out for each arrangement.
After the application of the short-time over current For the purpose of these tests, the ‘earth’ has the
with the voltage maintained at the terminals, the meter following meaning:
shall be allowed to return to the initial temperature with a) When the meter case is made of metal, the earth is
the voltage circuit(s) energised (about one hour). For the case itself placed on a flat conducting surface.
requirement, see 9.2.3
b) When the meter case or only a part of it is made
12.7.4 Test of Influence of Self-Heating of insulating material, the earth is a conductive
foil wrapped around the meter, touching all
The test shall be carried out as follows:
accessible conductive parts and connected to the
After the voltage circuits have been energised at flat conducting surface on which the meter base
reference voltage for at least 2 h, meters without any is placed. Where the terminal cover makes it
current in the current circuits, the rated maximum current possible, the conductive foil shall approach the
shall be applied to the current circuits. The meter error terminals and holes for the conductors within a
shall be measured at unity power-factor immediately distance of not more than 2 cm.
after the current is applied and then at intervals short
During the impulse and the a.c. voltage tests, the circuits
enough to allow a correct drawing to be made of the
which are not under test are connected to the earth as
curve of error variation as a function of time. The test
indicated hereafter. A flashover (capacitance discharge)
shall be carried out for at least 1 h and in any event until
during impulse test is not necessarily a criterion of
the variation of error during 20 min does not exceed 0.1
failure as this may occur in a position that does not
percent or the measurement uncertainties whichever is
damage and the manufacturer shall decide, whether or
greater. Maximum test duration shall not be more than
not to eliminate the cause. The meter shall withstand
2 h. The same test shall be carried out at 0.5 (lagging)
a.c. voltage as per 12.7.6.3 and insulation resistance is
power factor. The variation of error, measured as
as per 12.7.6.4.
specified, shall not exceed the values given in Table 13.
For test requirement see 9.3. In this sub-clause, the expression all the terminals
means the whole set of the terminals of the current
12.7.5 Test of Influence of Heating circuits, voltage circuits and, if any, auxiliary circuits
With each current circuit of the meter carrying rated having a reference voltage over 40 V.
maximum current and with each voltage circuits These shall be made in normal conditions of use.
(and with those auxiliary, voltage circuits which During the test, the quality of the insulation shall not be
are energised for periods of longer duration than impaired by dust or abnormal humidity.

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IS 13779 : 2020

Unless otherwise specified, the normal conditions for and appropriately insulated (for example, each circuit
insulation test are: connected to measuring transformer) the test shall be
a) Ambient temperature: 20 °C to 35 °C; made separately on each circuit.
b) Relative humidity: 45 percent to 95 percent; and During the test of a current circuit, the terminals of
the other circuits shall be connected to earth and the
c) Atmospheric pressure: 86 to 106 kPa (860 mbar to
impulse voltage shall be applied between one of the
1060 mbar).
terminals of the current circuit and earth. During the
12.7.6.2 Impulse voltage test test of a voltage circuit, the terminals of the other
circuits and one of the terminals of the voltage circuit
The impulse of 6 kV is applied ten times with one
under test shall be connected to earth and the impulse
polarity and then repeated with the other polarity.
voltage shall be applied between the other terminal of
The minimum time between the impulses shall be 3 s.
the voltage circuit and earth.
The waveform and the generator characteristics shall
be in accordance with IS 2071 (Part 1) with source The auxiliary circuits intended to be connected either
impedance 500 ohm ± 50 ohm and source energy directly to the mains or to the same voltage transformers
0.5 J ± 0.05 J as the meter circuits and with a reference voltage over
40 V shall be subjected to the impulse voltage test in
a) Impulse voltage tests for circuits and between the
the same conditions as those already given for voltage
circuits
circuits. The other auxiliary circuits shall not be tested.
The test shall be made independently on each circuit
(or assembly of circuits) which are insulated from the b) Impulse voltage test of electric circuits relative to
other circuits of the meter in normal use. The terminals earth
of the circuits which are not subjected to impulse All the terminals of the electric circuits of the meter,
voltage shall be connected to earth. including those of the auxiliary circuits with a reference
voltage over 40 V, shall be connected together.
Thus, when in normal use the voltage and the current
circuits of measuring elements are connected together, The auxiliary circuits with a reference voltage below or
the test shall be made on the whole. The other end equal to 40 V shall be connected to earth.
of the voltage circuit shall be connected to earth and The impulse voltage shall be applied between all the
impulse voltage shall be applied between the terminal electric circuits and earth.
of the current circuit and earth. When several voltage
circuits of a meter have a common point, this point 12.7.6.3  a.c. voltage test
shall be connected to earth and the impulse voltage The a.c. voltage test shall be carried out in accordance
successively applied between each of the free ends of with Table 21 for type test and acceptance test of new
the connections (or the current circuit connected to it) meters. For any subsequent test, the voltage applied
and earth. shall be 80 percent of the test voltage indicated in the
When in normal use, the voltage and the current Table 21.
circuits of the same measuring element are separated

Table 21 a. c. Voltage Tests

( Clause 12.7.6.3 )
Test Voltage (r.m.s.) Points of Application of the Test Voltage
(1) (2)
A) Test of meter with basic insulation. Test to be carried out with the case closed, cover and terminal cover in place
2 kV a) Between, on the one hand, all the current and voltage circuits as well as the auxiliary
circuits whose reference voltage is over 40 V, connected together, and, on the other hand,
earth
b) Between circuits not intended to be connected together in service
B) Test of meter with double insulation (for insulating encased meters). Test to be carried out with the case closed, cover and terminal
cover in place
4 kV a) Between, on the one hand, all the current and voltage circuits as well as the auxiliary
circuits whose reference voltage is over 40 V, connected together, and, on the other hand,
earth
2 kV b) Between circuits not intended to be connected together in service
- c) A visual inspection for compliance with the conditions of 6.7
40 V (for test in item d), if applicable d) Between on the one hand, all conductive parts inside the meter, connected together and,
on the other hand, all conductive parts outside the meter case that are accessible with the
test finger connected together

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IS 13779 : 2020

The test voltage shall be substantially sinusoidal, The meter shall be in operating condition:
having a frequency between 45 Hz and 55 Hz, and a) Voltage circuits and auxiliary power supply
applied for one minute for type test and acceptance test. circuits energized with reference voltages; and
The test duration for routine test shall be minimum 5 s.
The power source shall be capable of supplying at least b) Without any current in the current circuits and the
500 VA. current terminals shall be open circuit.

During the test no flashover, disruptive discharge, 12.9.2.1 Contact discharge

puncture shall occur. a) Direct Discharge — The test voltage of 8 kV shall
During the tests relative to earth, the auxiliary circuits be applied to metallic parts accessible in normal
with reference voltage equal to or below 40 V shall be operation.
connected to earth. Number of discharges = 10 (in both the polarity)
12.7.6.4 Insulation resistance test b) Indirect Discharge — The test voltage of
8 kV shall be applied to both vertical and horizontal
The insulation resistance test shall be carried out coupling planes in contact mode. In both vertical
in accordance with Table 22. The voltage shall be and horizontal plane, all faces of meter shall be
applied for a minimum of one minute (for type test exposed to the discharge.
and acceptance test) or more for the pointer of the
insulation tester to have come practically to rest. The Number of discharges = 10 ( in both the polarity)
insulation resistance test duration for routine test shall 12.9.2.2 Air discharge
be minimum 5 s.
a) Direct Discharge — The test voltage of 15 kV
Table 22 Insulation Resistance Test shall be applied to non-metallic parts accessible in
( Clause 12.7.6.4 ) normal operation.
Test Voltage Points of Application of the Test Insulation
Number of discharges = 10 (in both the polarity)
Voltage Resistance The application of the electrostatic discharge shall not
(1) (2) (3) produce a change in the cumulative register of more
500 ± 50 V dc a) Between, on the one hand, 5 MΩ than 0.01 kWh and the test output shall not produce a
all the current and voltage signal equivalent to more than 0.01 kWh. These values
circuits as well as the are based on the rated current of 5 A and 100 V of the
auxiliary circuits whose meter. For other voltage and current ratings, the value
reference voltage is over 40
V, connected together, and,
0.01 kWh has to be converted accordingly.
on the other hand, earth
12.9.3 Test for Immunity to Electromagnetic HF Fields
b) Between circuits not 50 MΩ
intended to be connected The test shall be carried out according to IS 14700
together in service (Part 4/Sec 3) or IEC 61000-4-20 under the following
NOTE — Where two or more voltage circuits are conditions:
permanently joined together, the combination may be a) Voltage and auxiliary circuits energised with
treated as one circuit for this test. reference voltage
12.8 Test of immunity to Earth/Phase Fault b) Frequency band: 80 MHz to 1000 MHz with
sweep of frequency step of 1 percent logarithm
It shall be verified that the earth/phase fault requirements
as fixed under 9.6 are satisfied. For test diagram, c) Unmodulated field: 10 V/m
see Annex E. d) Test severity level: 3
12.9.3.1 Without any current and the current circuit
12.9 Test for Electromagnetic Compatibility (EMC)
should be open
12.9.1 General Test Conditions The application of the HF field shall not produce
For all these tests, the meter shall be in its normal a change in the register of more than 0.01 kWh and
working position with the cover and terminal cover in the test output shall not produce a signal equivalent to
place. All parts intended to be earthed shall be earthed. more than 0.01 kWh. These values are based on the
After these tests, the meter shall show no damage. rated current of 5 A and 100 V of the meter. For other
voltage and current ratings, the value 0.01 kWh has to
12.9.2 Test for Immunity to Electrostatic Discharge be converted accordingly.
(ESD)
12.9.3.2 Test with current
The test shall be carried out according to
a) Meter in operating condition.
IS 14700 (Part 4/Sec 2), under the following conditions:
b) Voltage and auxiliary circuits energized with
Tested as table top equipment. reference voltage.
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IS 13779 : 2020

c) Basic current Ib and Cos θ = 1 h) Number of tests: 5 positive and 5 negative; and
During the test, the behaviour of the equipment shall not j) Repetition rate: maximum 1/min.
be perturbed and the variation of error shall be within the The application of test shall not produce change in
limits as specified in Table 17. Frequency at which the register of more than 0.01 kWh and the test output shall
meter is affected shall be reported. not produce a signal equivalent to more than 0.01 kWh.
These values are based on the rated current of 5A and
12.9.4 Fast Transient Burst Test
100 V of the meter. For other voltage and current ratings,
The test shall be carried out according to the value 0.01 kWh has to be converted accordingly.
IS 14700 (Part 4/Sec 4) under the following conditions:
During the test, a temporary degradation or loss of
a) Tested as table top equipment; function or performance is acceptable.
b) Meter in operating condition:
12.9.6 Radio Interference Measurement
1) Voltage and auxiliary circuits energized with
reference voltage, or The test for radio interference shall be carried out as per
IS 6873 (Part 2/Sec 1). The input to be applied to meter
2) With basic current in current circuit, PF is unity.
during test is reference voltage, load current between
c) Cable length between coupling device and EUT: 0.1 Ib to Ib at UPF.
1m
a) Test for conducted emission for the frequency range
d) Test voltage shall be applied in common mode (line 0.15 Mhz to 30 Mhz.
to earth) to:
The test shall be carried out on mains part as per
1) The voltage circuits; clause 4.3.3 of  IS 6873 (Part 2/Sec 1). For mains
2) The current circuits, if separated from the parts, the limit specify in column 2 and 3 of  Table 5
voltage circuits in normal operation; or of IS 6873 (Part 2/Sec 1) apply.
3) The auxiliary circuit; if separated from the b) Test for radiated emission for frequency range
voltage circuits in normal operation. 30 Mhz to 300 Mhz.
e) Test voltage on current and voltage circuit: 4 kV The test shall be carried out as per clause 5.3.3 or 5.3.4
f) Test voltage on auxiliary circuits with a reference of IS 6873 (Part 2/Sec 1). The limits specified in column
voltage above 40 V: 2 kV 2 and 3 of Table 7 or of  Table 9 respectively, of  IS 6873
g) Duration of test: 60 s at each polarity (Part 2/Sec 1) apply.
NOTE — Accuracy may be determined by the registration 12.10 Test of Accuracy Requirements
method or other suitable means.
12.10.1 General Test Conditions
During the test, temporary degradation or loss of function
or performance is acceptable, nevertheless the variation Determination of meter errors for the purpose of
of the error shall be within the limits as specified in verification of accuracy requirement (see 11) and
Table 17. verification of such errors for the purpose of other
requirements shall be carried out in a meter testing station
12.9.5 Surge Immunity Test having meter testing equipment of relevant accuracy
The test shall be carried out according to class as laid down in IS 12346.
IS 14700 (Part 4/Sec 5) under the following conditions The following test conditions shall be maintained:
with meter in operating condition:
a) The meter shall be tested in its case with cover in
a) Voltage and auxiliary circuits energized with position, all parts intended to be earthed shall be
reference voltage; earthed;
b) Without any current in the current circuits and the b) Before any tests are made, the circuits shall have
current terminals shall be open circuit; been energised for a time to reach thermal stability;
c) Cable length between surge generator and meter: c) In addition, for polyphase meters:
1m
1) The phase sequence shall be as marked on the
d) Tested in differential mode (line to line); diagram of connections, or
e) Phase angle: pulses to be applied at 60° and 240° 2) The voltages and currents shall be substantially
relative to zero crossing of a.c. supply; balanced (see Table 23 and 24).
f) Test voltage on the current and voltage circuits d) The minimum test period at any test point shall
(main lines): 4 kV, generator source impedance: contain sufficient number of power cycles
2 ohm (not less than 20 seconds)  to take care
g) Test voltages on auxiliary circuits with a reference instantaneous power Variation within a cycle.
voltage over 40 V: 1 kV; Generator source The maximum test period is however determined
impedance: 42 ohm; by homogeneity and resolution of test output
(see 6.11); and

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IS 13779 : 2020

e) The reference condition shall be as specified in 12.11 Test of Influence Quantities

Table 24. It shall be verified that the requirements of influence
Table 23 Voltage and Current Balance quantities as fixed under 11.1 and 11.2 are satisfied. Test
( Clauses 12.10.1 and 12.11 ) for variation caused by one influence quantity should
be performed independently with all other influence
Sl No. Polyphase Meters Class of Meters quantities at their reference conditions (see Table 23).
1 2 The continuous magnetic induction of 67 mT ± 5
(1) (2) (3) (4) percent (see Note 5 under Table 17) shall be obtained at
i) Each of the voltages ± 1 percent ±1 a distance of 5 mm from the surface of pole, by using
between line and neutral or percent the electromagnet according to Annex F energised with
between any two lines shall a d.c. current. The magnetic field shall be applied to
not differ from the average
all accessible surfaces of the meter. The value of the
corresponding voltage by
more than magneto-motive force to be applied shall generally be
1 000 ampere-turns.
ii) Each of the currents in the ± 2 percent ±2
current circuit shall not differ percent The continuous ‘abnormal’ magnetic induction of
from the average current by 0.2 T ± 5 percent (see Note 9 under Table 17) shall
more than be obtained at a distance of 5 mm from the surface of
iii) The phase displacements ± 2 deg ± 2 deg pole, by using the electromagnet according to Annex F,
of each of these currents energised with a d.c. current. The magnetic field shall
from the corresponding
line-to-neutral voltage,
be applied to all accessible surfaces of the meter. The
irrespective of the power value of the magneto-motive force to be applied shall
factor, shall not differ from generally be 10 000 ampere-turns.
each other by more than
The magnetic induction (see Note 6 under Table 17)
shall be obtained by placing the meter in the centre
Table 24 Reference Conditions
of a circular coil, 1 meter in mean diameter, of square
( Clause 12.10.1 ) section of small radial thickness relative to the diameter,
and having 400 ampere-turns.
Sl No. Influence Quantity Reference Permissible
Value Tolerances The abnormal a.c. magnetic induction of 10 mT ± 5
(1) (2) (3) (4) percent (see Note 9, under Table 17) shall be obtained
i) Ambient Reference ± 2 °C
by placing the meter at various orientations in the
temperature temperature or centre of a circular coil of square section (O.D. 400
(see Note 1) in its absence mm, I.D. 320 mm, depth 45 mm, 2 800 AT) produced
27 °C by a current of the same frequency as that of the voltage
ii) Voltage Reference ± 1 percent applied to the meter and under the most unfavourable
Voltage conditions of phase and direction.
(see Note 2)
12.12 Test of Ambient Temperature Influence
iii) Frequency Reference ± 0.3 percent
frequency It shall be verified that the ambient temperature
(see Note 2) influence as fixed under 11.3 is satisfied.
iv) Waveform Sinusoidal Distortion
voltage and factor less 12.13 Test of No-Load Condition
current than 2 percent When the voltage is applied with no current flowing in
v) Magnetic induction Magnetic ± 0.05 mT the current circuit, the test output of the meter shall not
of external origin induction produce more than one pulse.
at the reference equal to zero
frequency (see Note 3) For this test, the current circuit shall be open-circuit
NOTES and a voltage of 115 percent of the reference voltage
1 If the tests are made at a temperature other than the reference shall be applied to the voltage circuits.
temperature, including permissible tolerances, the results The minimum test period ∆t shall be:
shall be corrected by applying the appropriate temperature
coefficient of the meter. ∆ t = (600 × 106)/(k m Un Imax)
2 The reference conditions for voltage and frequency apply to ± 2 min for meters of class 1
both the measuring circuit and the auxiliary supply (ies).
3 This magnetic induction is that at the place of test without the ∆ t = (480 × 106)/(k m Un Imax)
presence of the meter and its connections. ± 2 min for meters of class 2

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IS 13779 : 2020

where b) Certain test results may fall outside the limits

k = the number of pulses emitted by the output indicted in Table 15 and 16, owing to uncertainties
device of the meter per kilowatt hour of measurements and other parameters capable of
(imp/kWh); influencing the measurements. However, if by
one displacement of the zero line parallel to itself
m = the number of measuring elements; by no more than the limits indicated in Table 25,
Un = the reference voltage in volts; and all the test result are brought within the limits
Imax = the maximum current in amperes. indicated in Table 15 and 16, the meter type shall
For transformer-operated meters with primary or be considered acceptable.
half-primary registers, the constant k shall correspond c) If the tests are made at a temperature other than
to the secondary values (voltage and currents). the reference temperature, including permissible
tolerances, the results shall be corrected by
12.14 Test of Starting Conditions applying the appropriate temperature coefficient
It shall be verified that the starting requirements as of the meter.
fixed under 11.5 are satisfied. Table 25 Interpretation of Test Results
12.15 Test of Meter Constant/Registration ( Clause 12.16)
The requirement of 11.6 shall be verified at one test Class of Meter
point, preferably at Imax UPF. 1 2
Although this verification is not required for meters Permissible displacement of the 0.5 1.0
having test output in the form of high resolution register, zero line, percent
a long period registration test shall be performed at
this test points to verify conformity of registration 12.17 Repeatability of Error Test
error, as indicated by the display of the meter and as Test shall be carried out at 0.05 Ib, Ib at UPF load under
distinct from any other external display used for testing reference test conditions. Six error samples shall be
purpose, within the limits specified in Table 15. taken by keeping a gap of time-intervals of 5 minutes
between each sample. Identical test condition shall be
12.16 Limits of Error and Interpretation of Test maintained throughout the test. For error test duration,
Results refer 6.11.
a) Limits of error as specified in 11.1 shall be verified. Requirement fixed under 11.7 shall be satisfied.

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IS 13779 : 2020

ANNEX A
( Clause 2 )
LIST OF REFERRED INDIAN STANDARDS

IS No. Title IS No. Title

1401 : 2008 Protection of persons and 9000 (Part 8) : 1981 Basic environmental testing
equipment by enclosure — procedures for electronic
Probes for verification and electrical items: Part 8
(second revision) Vibration (sinusoidal) test
2071 (Part 1) : 2016 High-voltage test techniques: 11000 (Part 2/Sec 1) Fire hazard testing: Part 2 Test
Part 1 General definitions : 2018 methods, Section 1 Glow-wire
and test requirements apparatus and common test
(third revision) procedure (second revision)
4905 : 2015 Random sampling and 12032 series Graphical symbols for
randomization procedures (all parts) diagrams in the field of
(first revision) electrotechnology
6873 (Part 2/Sec 1) Limits and methods of 12346 : 1999 Testing equipment for a.c.
: 2019 measurement of radio electrical energy meters
disturbance characteristics (first revision)
Part 2 Electromagnetic. 12360 : 1988 Voltage bands for electrical
Compatibility (EMC) — installations including
Requirements for household preferred voltages and
appliances, electric tools and frequency
similar apparatus/Section 1
Emission (third revision) 13360 Plastics — Methods of
(Part 6/Sec 17) : Testing: Part 6 Thermal
9000 (Part 2/Sec 3) Basic environmental testing 2017 properties Section 17
: 1977 procedures for electronic Determination of Temperature
and electrical items: Part of deflection Under
2 Cold test, Section 3 cold load-Plastics and Ebonite
test for non-heat dissipating (second revision)
items with gradual change of
temprature 14697 : 1999 a.c. static transformer
operated, watthour and
9000 (Part 3/Sec 3) Basic environmental testing var-hour meters class
: 1977 procedures for electronic and 0.2S and 0.5S and 1.0S —
electrical items: Part 3 Dry specification
heat test, Section 3 Dry heat
test for non-heat dissipating 14700 (Part 4/Sec 2) Electromagnetic compatibility
items with gradual change of : 2018 (EMC): Part 4 Testing and
temprature measurement techniques,
Section 2: Electrostatic
9000 (Part 5/Sec 2) Basic environmental testing discharge immunity test
: 1981 procedures for electronic and (second revision)
electrical items: Part 5 Damp
heat (cyclic) test, Section 2 14700 (Part 4/Sec 3) Electromagnetic compatibility
12 + 12 h cycle : 2018 (EMC): Part 4 Testing and
measurement techniques,
9000 (Part 7/Sec 1) Basic environmental testing Section 3 Radiated, radio
: 2018 procedures for electronic and frequency, electromagnetic
electrical items: Part 7 Impact field immunity test
test, Section 1 Shock test
(Test Ea) (second revision)

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IS 13779 : 2020

IS No. Title IS No. Title

14700 (Part 4/Sec 4) Electromagnetic compatibility IS/IEC 60529 : Degrees of protection
: 2018 (EMC): Part 4 Testing and 2001 provided by enclosures
measurement techniques, (IP CODE)
Section 4 Electrical fast IEC 60068-2-75 : Environmental testing —
transient/burst immunity test 2014 Part 2-75: Tests — Test Eh:
(second revision) Hammer tests
14700 (Part 4/Sec 5) Electromagnetic compatibility IEC 61000-4-20 : Electromagnetic compatibility
: 2019 (EMC): Part 4 Testing and 2010 (EMC) — Part 4-20:
measurement techniques, Testing and measurement
Section 5 Surge immunity test techniques — Emission and
(first revision) immunity testing in transverse
electromagnetic (TEM)
waveguides

ANNEX B
( Clause 8.2 )
RELATIONSHIP BETWEEN AMBIENT AIR TEMPERATURE AND RELATIVE HUMIDITY

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IS 13779 : 2020

ANNEX C
( Table 17 Note 4 )

TEST CIRCUIT DIAGRAM FOR d.c. AND EVEN HARMONICS

C-1 CIRCUIT FOR HALF WAVE RECTIFICATION

NOTES
1 The balancing impedance shall be equal to the equipment under test (EUT) to ensure the measurement accuracy.
2 It is recommended to use a meter of same type as the EUT in place of balancing impedance.
3 The rectifier diodes shall be of the same type.
4 To improve the balancing condition an additional resistor or RB can be introduced in both paths. Its value should be approximately
10 times the value of the EUT.
5 The influence of the d.c. components and even harmonics in the a.c. current shall be checked at 0.5 Ib, 0.5 Imax and any current between
0.5 Ib and 0.5 Imax. Current in the standard meter is 2/√2 times the current in meter under test [for example, for 0.5 Ib in meter under test,
current in standard meter will be (2/√2) 0.5 Ib].
6 With above connections, the EUT will measure half of the energy measured by standard meter.

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IS 13779 : 2020

C-2 HALF-WAVE RECTIFIED WAVEFORM

C-3 HALF-WAVE HARMONIC CURRENT

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IS 13779 : 2020

ANNEX D
( Clause 12.7.2 )
VOLTAGE WAVE FROM THE TESTS OF INFLUENCE OF SUPPLY VOLTAGE

Fig. D-1 Voltage Interruptions of Δ U = 100 Percent, 1s

Fig. D-2 Voltage Interruptions of Δ U = 100 Percent, 20 ms

Fig. D-3 Voltage Dips of Δ U = 50 Percent

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IS 13779 : 2020

ANNEX E
( Clauses 9.6 and 12.8 )
TEST CIRCUIT DIAGRAM FOR THE TEST OF IMMUNITY TO EARTH FAULT

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IS 13779 : 2020

ANNEX F
( Clause 12.11 )
ELECTROMAGNET FOR TESTING THE INFLUENCE OF
EXTERNALLY PRODUCED MAGNETIC FIELDS
All dimensions in mm

Meter under Test

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IS 13779 : 2020

ANNEX G
( Clause 12.2.2.1 )
RECOMMENDED SAMPLING PLAN

G-1 LOT A sample of N1 meters selected according to column

2 of Table 26 shall be tested for the above tests.
G-1.1 In any consignment, all the meters of the same Any meter failing in any one of these tests shall be
type and rating manufactured by the same factory considered defective. If the number of defectives found
during the same period shall be grouped together to in the sample is less than or equal to C1, the lot shall
constitute a lot. be considered to be conforming to these tests. If the
number of defectives is greater than or equal to C2, the
G-1.2 Sample shall be tested from each lot for lot shall be considered as not conforming to these tests.
ascertaining the conformity of the meters to the If the number of defectives is between C1 and C2, a
requirements of specified acceptance test. further sample of N2 meters shall be taken according to
column 3 of Table 26 and subjected to these tests. If the
G-2 SCALE OF SAMPLING
number of defectives in two samples combined is less
G-2.1 The number of meters to be selected from the than C2, the lot shall be considered as conforming to
lot depends upon the size of the lot and shall be in these tests, otherwise rejected.
accordance with Table 26: G-3.2 Tests of Insulation Resistance, a.c. Voltage
Table 26 Sampling Plan Tests, Test of Power Consumption, Test of Meter
( Clause G-2.1 ) Constant/Registration and Limits of Error
From the sample of meters which have been drawn
Lot Size N1* N2** (N1 + N2) C1 C2
according to G-3.1 and those that have passed all tests
(1) (2) (3) (4) (5) (6) of G-3.1, a sample of 8 meters shall be tested, all of
Up to 300 8 - 8 0 - which shall pass for conformity to these tests. If any
301 to 500 13 13 26 0 2 of the meters fails in any of these tests, the whole lot
501 to 1000 20 20 40 0 3
shall be declared not conforming to the requirements
of these tests.
1001 and above 32 32 64 1 4
G-3.3 Tests for Repeatability of Error
*Size of the first sample
**Size of the second sample Above tests shall be carried out on 3 samples selected
from above 8 meters under clause G-3.2 and shall be
G-2.2 The meters shall be taken at random from the lot. tested for repeatability of error tests separately. If any
The procedure given in IS 4905 may be adapted. one of the meters fails the whole lot shall be declared
not conforming to the requirements of these tests.
G-3 NUMBER OF TESTS AND CRITERIA FOR
ACCEPTANCE G-3.4 The lot shall be considered as conforming to this
specification, if provisions of G-3.1, G-3.2 and G-3.3
G-3.1 Test of No Load Condition and Starting are satisfied.
Condition

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IS 13779 : 2020

ANNEX H
( Clause 7.2 )
STANDARD CONNECTION DIAGRAMS

The standard connection diagrams are given below. phase of a single phase supply is generally marked
The phase supply terminals ate generally marked ‘M’. It should be noted that each individual metered
as ‘R’, ‘Y’ and ‘I’ though other conventions are also connection for independent load should be given an
acceptable if suitably marked on the terminal block independent set of phase and neutral connections direct
cover. The neutral terminal marked as ‘N’ and the from the supply side.

Fig. H-1 Single Phase Two Wire Meter

Fig. H-2 Single Phase Two Wire Meter Symmetrical Connections

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IS 13779 : 2020

Fig. H-3 Three Phase Three Wire Meter for Direct Connection

Fig. H-4 Three Phase Three Wire Meter for Current Transformers

Fig. H-5 Three Phase Four Wire Single Tariff Meter for Direct Connection

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IS 13779 : 2020

Fig. H-6 Three Phase Four Wire Meter with Current Transformers

Fig. H-7 Three Phase Four Wire Meter for Direct Connection
(Meters with no terminals for current circuits, i.e, load current carrying conductors are not terminated at the
meter and are passed through current measuring sensors)

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IS 13779 : 2020

ANNEX J
( Foreword )
COMMITTEE COMPOSITION
Equipment for Electrical Energy Measurement, tariff and Load Control Sectional Committee, ETD 13

Organization Representative (s)

Central Power Research Institute, Bhopal Shri B. A. Sawale (Chairman)
Adani Power Limited, Ahmedabad Shri Uday Trivedi
Shri Manoj Taunk (Alternate)
CESC Limited, Kolkata Shri Udayan Ganguly
Ms Susmita Sen (Alternate I)
Shri Santosh Chattopadhyay (Alternate II)
Central Electricity Authority, New Delhi Shrimati Vandana Singhal
Central Power Research Institute, Bengaluru Shri V. Shivakumar
Shrimati Viji Bharathi (Alternate I)
Shri V. Suresh (Alternate II)
Central Power Research Institute, Noida Shrimati Mridula Jain
Cyanconnode Private Limited, Gurugram Shri Deepak Nimare
Shri Subir Majumder (Alternate)
Elymer International Private Limited, Faridabad Shri Vipin Panwar
Enernovation Private Limited, Udaipur Shri Surendra Jhalora
Genus Power Infrastructures Limited, Jaipur Shri Ranvir Singh Rathore
Shri Bajrang Lal Agarwal (Alternate I)
Shri Anukram Mishra (Alternate II)
HPL Electric and Power Limited, Noida Shri C. P. Jain
Shri Sundeep Tandon (Alternate I)
Shri Ramveer Gupta (Alternate II)
Indian Electrical and Electronics Manufacturers Shri J. Pande
Association (IEEMA), New Delhi Shri Akeel Khan (Alternate)
Kalki Communication Technologies Private Limited, Shri Vinoo S. Warrier
Bengaluru Shri Balagopalan Mathoor (Alternate)
Landis + Gyr Limited, Noida Shri Anand Srivastava
Shri Rameshwar Dubey (Alternate I)
Shri Aashish Gaur (Alternate II)
Larsen and Toubro (L & T) Limited, Mysore Shri Sanjay Ahuja
Shri D. V. Kulkarni (Alternate I)
Shri Sujith Unnikrishnan (Alternate II)
Maharashtra State Electricity Distribution Company Mr Manish Wath
Limited, Mumbai
Narnix Technolabs Private Limited, New Delhi Shri Narang N. Kishor
National Smart Grid Mission, Gurugram Shri Atul Bali
Shri Sundeep Reddy (Alternate)
Secure Meters Limited, Udaipur Shri Madhur Kumar Srivastava
Shri Rajnish Kumar Ameta (Alternate)

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IS 13779 : 2020

Organization Representative (s)

Tata Power - Delhi Distribution Ltd, New Delhi Shri Subhadip Ray Chaudhuri
Shri Nitin Marjara (Alternate)
Tata Power Limited, Mumbai Shri Ajay Potdar
Shri Devanjan Dey (Alternate)
Yadav Measurements Private Limited, Udaipur Shri Bal Mukund Vyas
Shri N. K. Bhati (Alternate)
Zera India Private Limited Shri Shailendra Goyal
BIS Directorate General Shri Rajeev Sharma, Scientist ‘F’ and Head (ETD)
[ Representing Director General ( Ex-officio ) ]

Member Secretary
Ms Meghna Mudgal
Scientist ‘B’ (ETD), BIS

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 Free Standard provided by BIS via BSB Edge Private Limited to Kartikeya sharma -
gandhinagar(kartikeya.sharma@gmail.com) 61.2.224.16 [for non-commercial use only].
 Free Standard provided by BIS via BSB Edge Private Limited to Kartikeya sharma -
gandhinagar(kartikeya.sharma@gmail.com) 61.2.224.16 [for non-commercial use only].

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian Standards Act, 2016 to promote harmonious
development of the activities of standardization, marking and quality certification of goods and attending to
connected matters in the country.

Copyright

BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without
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copyright be addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed
periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are
needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards
should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of
‘BIS Catalogue’ and ‘Standards: Monthly Additions’.
This Indian Standard has been developed from Doc No.: ETD 13 (11300).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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