Ansi C12 PDF
Ansi C12 PDF
Ansi C12 PDF
1-2008
Secretariat:
The information in this publication was considered technically sound by the consensus of persons
engaged in the development and approval of the document at the time it was developed. Consensus
does not necessarily mean that there is unanimous agreement among every person participating in the
development of this document.
NEMA standards and guideline publications, of which the document contained herein is one, are
developed through a voluntary consensus standards development process. This process brings together
volunteers and/or seeks out the views of persons who have an interest in the topic covered by this
publication. While NEMA administers the process and establishes rules to promote fairness in the
development of consensus, it does not write the document and it does not independently test, evaluate,
or verify the accuracy or completeness of any information or the soundness of any judgments contained
in its standards and guideline publications.
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purposes or needs. NEMA does not undertake to guarantee the performance of any individual
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In publishing and making this document available, NEMA is not undertaking to render professional or
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exercise of reasonable care in any given circumstances. Information and other standards on the topic
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additional views or information not covered by this publication.
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of the statement.
ANSI C12.1-2008
Published by
No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the
prior written permission of the publisher.
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ANSI C12.1-2008
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ANSI C12.1-2008
TABLE OF CONTENTS
Foreword .........................................................................................................................................vii
1 Scope and references...................................................................................................................... 1
1.2 References.......................................................................................................................... 1
2 Definitions ........................................................................................................................................ 3
3 Standards and standardizing equipment ....................................................................................... 10
3.1 Scope ................................................................................................................................ 10
3.2 Final authority.................................................................................................................... 10
3.3 Traceability paths to NIST................................................................................................. 10
3.3.1 Direct transfer ...................................................................................................... 10
3.4 Meter laboratory ................................................................................................................ 11
3.4.1 Laboratory conditions........................................................................................... 11
3.4.2 Reference temperature and humidity .................................................................. 12
3.4.3 Laboratory power sources ................................................................................... 12
3.5 Meter shop ........................................................................................................................ 12
3.6 Laboratory standards ........................................................................................................ 12
3.6.1 Basic reference standards ................................................................................... 12
3.6.2 Transport standards............................................................................................. 12
3.7 Periodic verification of reference standards ..................................................................... 12
3.8 Portable/field/working standard watthour meters ............................................................. 12
3.9 Performance records ........................................................................................................ 12
3.10 Performance requirements for standard watthour meters ................................................ 13
3.10.1 General test conditions ........................................................................................ 13
3.10.2 Accuracy tests for portable and reference standards .......................................... 13
4 Acceptable performance of new types of electricity metering devices and associated
equipment ...................................................................................................................................... 15
4.1 General ............................................................................................................................. 15
4.1.1 Acceptable metering devices ............................................................................... 15
4.1.2 Adequacy of testing laboratory ............................................................................ 15
4.1.3 Retesting of new meter type ................................................................................ 15
4.1.4 Test documentation ............................................................................................. 15
4.1.5 Test device........................................................................................................... 15
4.1.6 Tests performed in series .................................................................................... 15
4.1.7 Handling of failed device...................................................................................... 15
4.1.8 Restart testing ...................................................................................................... 15
4.1.9 Reporting of test metering devices ...................................................................... 16
4.2 Types of metering devices ................................................................................................ 16
4.2.1 Basic type............................................................................................................. 16
4.2.2 Variations within the basic type ........................................................................... 16
4.2.3 Type designation.................................................................................................. 16
4.2.4 Acceptance of basic types in whole or part ......................................................... 16
4.2.5 Minor variations.................................................................................................... 16
4.2.6 Special types........................................................................................................ 16
4.3 Specifications for design and construction ....................................................................... 16
4.3.1 Sealing ................................................................................................................ 16
4.3.2 Enclosures ........................................................................................................... 16
4.3.3 Terminals and markings....................................................................................... 17
4.3.4 Construction and workmanship ........................................................................... 17
4.3.5 Provision for adjustment ...................................................................................... 17
4.4 Selection of metering devices for approval tests .............................................................. 17
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ANSI C12.1-2008
APPENDICES
A ..................................................................................................................................................... 64
B ..................................................................................................................................................... 74
C..................................................................................................................................................... 93
D..................................................................................................................................................... 95
E ..................................................................................................................................................... 96
F ..................................................................................................................................................... 97
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ANSI C12.1-2008
TABLES
1 Portable and Reference Standards Percent Errors ....................................................................... 14
2 Table of Failures Based on the Number of Metering Devices Tested........................................... 19
3 List of Tests.................................................................................................................................... 20
4 Starting Load Test.......................................................................................................................... 21
5 Load Performance Test ................................................................................................................. 21
6 Effect of Variation of Power Factor for Single-Element Meters ..................................................... 22
7 Effect of Power Factor for Two-Element Meters:........................................................................... 22
8 Effect of Variation of Power Factor for Two-Element Three-Phase Four-Wire Wye Meters ......... 23
9 Effect of Variation of Power Factor for Three-Element Three-Phase Four-Wire Wye Meters .......... 23
10 Effect of Variation of Voltage ......................................................................................................... 24
11 Effect of Variation of Voltage on Solid-State Auxiliary Devices ..................................................... 24
12 Effects of Variation of Frequency................................................................................................... 25
13 Equality of Current Circuits in the Three-Wire Element for Single-Element Meters ...................... 25
14 Equality of Current Circuits in the Three-Wire Element for Multi-Element .................................... 26
15 Equality of Current Circuits between Elements for Multi-Element Meters..................................... 26
16 Temperature-Rise Test Specifications........................................................................................... 27
17 Effect of Internal Heating ............................................................................................................... 32
18 Effect of Tilt .................................................................................................................................... 33
19 Test for Independence of Elements in Two-Element Meters......................................................... 35
20 Test for Independence of Elements in Three-Element Meters ...................................................... 36
21 Effect of External Magnetic Field ................................................................................................... 38
22 Effect of Variation of Ambient Temperature................................................................................... 39
23 Effect of Variation of Temperature on Solid-State Auxiliary Devices............................................. 40
24 Effect of Temporary Overloads on Accuracy ................................................................................. 40
25 Effect of Current Surge in Ground Conductor................................................................................ 41
26 Test Modes, Voltage, and Application for Each External Connection Group—Oscillatory
Test ................................................................................................................................................ 44
27 Variable Interval Plan ..................................................................................................................... 56
28 Performance Test—Pulse Devices................................................................................................ 60
29 Portable Standard Watthour Meter ................................................................................................. 90
30 Reference Standard Watthour Meters ........................................................................................... 92
FIGURES
1 Dimensions for jumper bars of simulated meter temperature-rise test for single-phase
and polyphase meters (maximum rating 100 A) ............................................................................ 29
2 Dimensions for jumper bars of simulated meter temperature-rise test for single-phase
and polyphase meters (maximum rating 101 – 200 A rating)........................................................ 30
3 Dimensions for jumper bars of simulated meter temperature-rise test for single-phase
and polyphase meters (maximum rating 201 – 320 A rating)........................................................ 31
4 Electrical Fast Transient/Burst Test # 25....................................................................................... 42
5 Electrical Fast Transient/Burst Test # 25....................................................................................... 43
6 Typical test layout for radiated susceptibility—Test 26 and radiated and conducted
emissions—Test 27 ....................................................................................................................... 46
7 Typical wiring detail for self contained meters for radiated susceptibility —Test 26 and
radiated and conducted emissions —Test 27 ............................................................................... 47
8 Typical wiring detail for transformer rated meters for radiated susceptibility —Test 26 and
radiated and conducted emissions —Test 27 ............................................................................... 48
9 Typical GTEM test layout for Radiated Susceptibility Test............................................................ 49
10 Sunlight Interference Test.............................................................................................................. 62
11 Variable Angles Sunlight Interference Test ................................................................................... 63
B.1 Traceability path diagram............................................................................................................... 76
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ANSI C12.1-2008
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ANSI C12.1-2008
Most of the meter specifications have been retained from the previous edition. Comments about the
significant changes follow. To help insure that new electronic equipment is as dependable as possible, an
oscillatory surge withstand test was added. Also, the requirement when retesting a new meter type was
made more restrictive. Minor changes to the temperature rise test were made to make testing more
uniform. Supplementary information was added to the equality of current circuits test, the electrostatic
discharge test, and the relative humidity test to clarify the testing process. For several of the tests specific
details for successful passing criteria have been included. References to external documents were
updated.
The Secretariat of the Accredited Standards Committee on Electricity Metering, C12, is held by the National
Electrical Manufacturers Association (NEMA) and the National Institute of Standards and Technology. At the
time this standard was processed and approved, the C12 Committee had the following members:
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ANSI C12.1-2008
The following members of the C12.1 Committee were actively involved in the revision of this standard:
S. Weikel, Chairman
M. Anderson G. Mayfield
N. Balko J. McEvoy
L. Barto H. Millican
B. Cain A. Moise
R. Collins T. Morgan
B. Cook T. Nelson
C. Crittenden D. Nguyen
J. DeMars V. Nguyen
L. Durante D. Nordell
D. Ellis L. Pananen
T. Everidge C. Partridge
C. Gomez A. Rashid
W. Hardy A. Snyder
Bob Hughes D. Tandon
Brent Hughes A. Thompson
B. Kingham J. Thurber
L. Kotewa J. Voisine
T. Lawton S. Weikel
R. Lokys J. West
E. Malemezian
In addition, the following comprised the Editorial Committee for the current Revision of C12.1:
L. Barto
E. Malemezian
P. Orr
A. Snyder
S. Weikel
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ANSI C12.1-2008
This Code establishes acceptable performance criteria for new types of ac watthour meters, demand
meters, demand registers, pulse devices, and auxiliary devices. It describes acceptable in-service
performance levels for meters and devices used in revenue metering. It also includes information on related
subjects, such as recommended measurement standards, installation requirements, test methods, and test
schedules. This Code for Electricity Metering is designed as a reference for those concerned with the art of
electricity metering, such as utilities, manufacturers, and regulatory bodies.
1.2 References
The following publications shall be used in conjunction with this standard. When they are superseded by an
approved revision, the revision shall apply:
ASQ Z1.9-2003, Sampling Procedures and Tables for Inspection by Variables for Percent Nonconforming
ASTM B117-2003, Standard Practice for Operating Salt Spray (Fog) Apparatus
ASTM G155 2005, Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-
Metallic Materials
Code of Federal Regulations (Telecommunication) CFR 47, Part 15—Radio Frequency Devices, Subparts
A—General and B—Unintentional Radiators
Chapter 13 “The Customers’ Premises, Service and Installations”, Handbook for Electricity Metering, 10th
Edition, Washington, D.C.: Edison Electric Institute, 2002
IEEE 1-2000, IEEE Recommended Practice: General Principles for Temperature Limits in the Rating of
Electric Equipment and for the Evaluation of Electrical Insulation
IEEE C37.90.1-2002, IEEE Standard Surge Withstand Capability (SWC) Tests for Protective Relays and
Relay Systems Associated with Electric Power Apparatus
IEEE C62.41.1-2002, IEEE Guide on the Surge Environment in Low-Voltage (1000 V and less) AC Power
Circuits
IEC 60068-2-6 (1995), Environmental Testing - Part 2: Tests, Test Fc: Vibration (Sinusoidal)
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ANSI C12.1-2008
IEC 60068-2-27 (1987), Environmental Testing, Part 2: Tests, Test Ea and Guidance: Shock.
IEC 61000-4-2 (2001), Electromagnetic Compatibility (EMC) - Part 4-2: Testing and Measurement
Techniques - Electrostatic Discharge Immunity Test
IEC 61000-4-4 (2004), Electromagnetic Compatibility (EMC), Part 4-4: Testing and Measurement
Techniques - Electrical Fast Transient/Burst Immunity Test
International Safe Transit Association, Test Procedure 1A, Performance Test for Individual Packaged-
Products Weighing 150 lb. (68 kg) or Less, (revision date: 2001) , Vibration and Shock
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ANSI C12.1-2008
2 Definitions
The definitions given apply specifically to the subject as treated in this American National Standard. Most
of them are grouped under general terms, such as watthour meter, and all are given numbers for
identification. For additional definitions, see IEEE 100.
2.1 accuracy: The extent to which a given measurement agrees with the defined value.
2.2 alternate display: A display sequence usually containing constants and diagnostic information.
2.3 auxiliary device: An add-on device mounted under the meter cover that adds functionality to the
meter device.
2.4 Blondel's theorem: In a system of N conductors, N-1 meter elements, properly connected, will
measure the active power or energy taken. The connection must be such that all voltage coils have
a common tie to the conductor in which there is no current coil.
2.5 calibration: Comparison of the indication of the instrument under test, or registration of the meter
under test, with an appropriate standard.
2.6 certified meter type: A metering device which is tested and certified to meet the certification
testing as specified in this standard for a specific meter type. It shall include any optional circuit
boards, devices, or modules enclosed within the meter cover as part of this certified meter type.
2.7 coupling-capacitor voltage transformer (CCVT): A voltage transformer comprised of a capacitor
divider and an electromagnetic unit so designed and interconnected that the secondary voltage of
the electromagnetic units is substantially proportional to, and in phase with, the primary voltage
applied to the capacitor divider for all values of secondary burdens within the rating of the coupling-
capacitor voltage transformer.
2.8 class designation: See watthour meter-class designation (2.94).
2.9 creep: A continuous apparent accumulation of energy in a meter with voltage applied and the load
terminals open circuited.
2.10 customer alert: A switching output used to indicate events or conditions.
2.11 demand: The average power or a related quantity over a specified interval of time. Demand is
expressed in kilowatts, kilovolt-amperes, kilovars or other suitable units.
2.12 demand constant (pulse receiver Kd): The value of the measured quantity for each received
pulse, expressed in kilowatts per pulse, kilovars per pulse, or other suitable units.
2.13 demand interval: The specified interval of time on which a demand measurement is based.
Intervals such as 15, 30, or 60 minutes are commonly specified.
2.14 demand interval deviation: The difference between the measured demand interval and the
specified demand interval, expressed as a percentage of the specified demand interval.
2.15 demand interval – rolling (RDI): An interval of time, the beginning which progresses in steps of
sub-intervals and where the interval length is equal to an integer multiple of sub-intervals.
2.16 demand-maximum: The highest demand measured over a selected period of time.
2.17 demand meter: A metering device that indicates or records demand.
2.18 demand meter – block interval (integrating): A meter that integrates power or a related quantity
over a fixed-time interval, and indicates or records the average.
2.19 demand meter – lagged: A demand meter with an approximately exponential response.
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ANSI C12.1-2008
2.20 demand meter (lagged) – time characteristic: The nominal time required for 90% of the final
indication, with constant load suddenly applied.
NOTE—The time characteristic of demand meters (lagged) describes the exponential response of the meter to
the applied load. The response is continuous and independent of the selected discrete time intervals.
2.21 demand register: A device for use with an electricity meter, that indicates and/or records demand.
2.22 demand register – block interval: A demand register that indicates and/or records the maximum
demand obtained by arithmetically averaging the meter registration over a regularly repeated time
interval.
2.23 demand register – continuous cumulative: The sum of all previous billing period maximum
demands and the highest demand to date for the present billing period.
2.24 demand register – cumulative: A register that indicates the sum of the previous maximum
demand readings prior to reset.
NOTE—When reset, the present reading is added to the previously accumulated readings. The maximum
demand for the present reading period is the difference between the present and previous readings.
2.25 demand register – indicating single-pointer form: An indicating demand register from which the
demand is obtained by reading the position of a pointer relative to the markings on a scale.
NOTE—When reset, the single pointer returns to zero.
2.26 demand register – dual range (single pointer form): An indicating demand register having an
arrangement for changing the full-scale capacity from one value to another, usually by reversing the
scale plate.
NOTE—For example, Scale Class 1/2; Scale Class 2/6. An interlock assures proper scale and scale-class
relation.
2.27 demand register – full-scale value: The maximum scale capacity of the register. If a multiplier
exists, the full-scale value will be the product of the maximum scale marking and the multiplying
constant.
2.28 demand register – scale class: Denotes, with respect to single-pointer form, dual-range single-
pointer form, or cumulative-form demand registers, the relationship between the full-scale value of
the register and the test kVA rating of the meter with which the register is used.
2.29 display: A means of visually identifying and presenting measured or calculated quantities and other
information.
2.30 electricity meter: A device that measures and registers the integral of an electrical quantity with
respect to time.
2.31 element: An element is the combination of signal sensing units, resulting in an output proportional
to the measured quantities.
NOTES
1 For example, if one input signal is voltage and the other input signal is current, then the output is power
(watts).
2 The term element is also referred to as stator.
3 Electricity meters normally include 1, 1-1/2, 2, 2-1/2, or 3 elements.
4 The 2-1/2 element meter refers to 2 stator 4-wire wye meter as described in section A.2.7.2.
5 The three wire element is a single element using the sum of two current circuits and one potential circuit.
2.32 electronic storage register: An electronic circuit where data is stored for display and/or retrieval.
2.33 end-of-interval indicator (EOI): An indicator for the end of the demand interval for non-
rolling(block)-interval demand, or the end of the sub-interval for rolling-interval demand.
2.34 energy: The integral of active power with respect to time.
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ANSI C12.1-2008
2.35 energy flow: Energy flow from line to load terminals shall be considered as energy delivered to the
load terminals of the meter. Energy in the opposite direction, i.e., from load to line terminals, shall be
considered as received. The line and load terminals are as specified in the Handbook for Electricity
Metering, (Chapter 13).
2.36 firmware: A control program stored in non-volatile memory and considered to be an integral part of
an electronic device.
2.37 homogeneous meter group: A lot or population of meters from which a random sample is selected
that, as far as is practicable, consists of meters of the same basic type or model designation, have
the same general construction, produced by the same manufacturer, and have the same
relationship of parts.
2.38 interface: The means for transmitting information between the meter or register and peripheral
equipment.
2.39 laboratory - meter: A laboratory responsible for maintaining reference standards and assigning
values to the working standards used for the testing of electricity meters and auxiliary devices.
2.40 laboratory – independent standards: A standards laboratory maintained by, and responsible to, a
company or authority that is not under the same administrative control as the laboratories or
companies submitting instruments for calibration.
2.41 metering devices: Equipment used in energy revenue metering; such as watthour meters, demand
meters, demand and TOU registers and various forms of pulse initiating, receiving and totalizing
devices.
2.42 normal mode: The operating mode of the register usually displaying the billing data.
2.43 phase-shifting transformer: An assembly of one or more transformers intended to be connected
to a polyphase circuit so as to provide voltages in the proper phase relations for energizing
varmeters, varhour meters, or other measurement equipment. This type of transformer is
sometimes referred to as a phasing transformer.
2.44 phasor: A complex number, associated with sinusoidally varying electrical quantities, such that the
absolute value (modulus) of the complex number corresponds to either the peak amplitude or rms
value of the quantity, and the phase (argument) to the phase angle at zero time. By extension, the
term "phasor" can also be applied to impedance and related complex quantities that are not time-
dependent.
2.45 power – active: The time average of the instantaneous power over one period of the wave.
NOTE—For sinusoidal quantities in a two-wire circuit, it is the product of the voltage, the current, and the cosine
of the phase angle between them. For nonsinusoidal quantities, it is the sum of all the harmonic components,
each determined as above. In a polyphase circuit, it is the sum of the active powers of the individual phases.
2.46 power – apparent: The product of rms current and rms voltage for any wave form in a two-wire
circuit. For sinusoidal quantities, apparent power is equal to the square root of the sum of the
squares of the active and reactive powers in both two-wire and polyphase circuits.
2.47 power – reactive: For sinusoidal quantities in a two-wire circuit, reactive power is the product of the
voltage, the current, and the sine of the phase angle between them, using the current as reference.
2.48 power factor: The ratio of active power to the apparent power.
2.49 precision: The repeatability of measurement data, customarily expressed in terms of standard
deviation.
2.50 pulse: A change of state of an electrical signal that conveys an event or information.
NOTE—A sudden change of voltage or current produced, for example, by the closing or opening of a contact.
2.51 pulse amplifier or relay: A device used to change the amplitude or waveform of a pulse for
retransmission to another pulse device.
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ANSI C12.1-2008
2.52 pulse capacity: The number of pulses per demand interval that a pulse receiver can accept and
register without loss.
2.53 pulse device (for electricity metering): The functional unit for initiating, transmitting,
retransmitting, or receiving electric pulses, representing finite quantities, such as energy, normally
transmitted from some form of electricity meter to a receiver unit.
2.54 pulse initiator: Any device, mechanical or electrical, used with a meter to initiate pulses, the
number of which are proportional to the quantity being measured. It may include an external
amplifier or auxiliary relay or both.
2.55 pulse-initiator output constant (Ke or KWHC): The value of the measured quantity for each
outgoing pulse of a pulse initiator, expressed in kilowatt hours per pulse, kilovarhours per pulse, or
other suitable units.
2.56 pulse-initiator output ratio (R/P or Mp): The number of revolutions of the meter rotor per output
pulse of the pulse initiator.
2.57 pulse rate – maximum: The number of pulses per second at which a pulse device is nominally
rated.
2.58 pulse receiver: The unit that receives and registers the pulses.
2.59 pulse recorder: A device that receives and records pulses over successive demand intervals.
2.60 pulse-recorder channel: One individual input, output, and intervening circuitry required to record
pulse data.
2.61 Q-hour meter: An electricity meter that measures the quantity obtained by effectively lagging the
applied voltage to a watthour meter by 60 degrees. This quantity is used with watthours in
calculating quadergy (varhours).
2.62 quadergy: The integral of reactive power with respect to time.
2.63 shop – meter: A place where meters are inspected, repaired, tested, and adjusted.
2.64 simulated meter: A meter cover, base, and jumper bars constructed to represent the thermal
characteristics of a specific class of watthour meter to be used in the testing of a meter socket and
in determining the empirical temperature rise of the test meter for temperature rise at continuous
ampere rating.
2.65 standards – national: Standard electrical quantities that are maintained by the National Institute of
Standards and Technology (NIST).
2.66 standard watthour meter – basic current range: The current range of a multirange standard
watthour meter designated by the manufacturer for its calibration (normally the 5 A range).
2.67 standard watthour meter – basic voltage range: The voltage range of a multirange standard
watthour meter designated by the manufacturer for its calibration (normally the 120 V range).
2.68 standard watthour meter – rated current: The nameplate current for each range of a standard
watthour meter.
NOTE—The main adjustment of the meter is ordinarily made with rated current on the basic current range.
2.69 standard watthour meter – rated voltage: The nameplate voltage for a meter or for each range of
a standard watthour meter.
NOTE—The main adjustment of the standard meter is ordinarily made with rated voltage on the basic voltage
range.
2.70 test – acceptance: A test to demonstrate the degree of compliance of a device with the purchaser's
requirements.
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ANSI C12.1-2008
2.71 test accuracy – in-service: A test made during the period that the meter is in service. It may be
made on the customer's premises without removing the meter from its mounting, or by removing the
meter for test either on the premises or in a laboratory or meter shop.
2.72 test – accuracy – referee: A test made by or in the presence of one or more representatives of a
regulatory body or other impartial agency.
2.73 test – accuracy – request: A test made at the request of a customer.
2.74 test amperes (TA): The load current specified by the manufacturer for the main calibration
adjustment.
2.75 test – approval: A test of one or more meters or other items under various controlled conditions to
ascertain the compliance of the type of which they are a sample with the appropriate standard.
2.76 test mode: A separately activated sequence that saves billing data while displaying test data. It
reactivates the billing data to the register when the normal mode is resumed.
2.77 timebase primary: A timing system established from the frequency of the power line or other
reference source.
2.78 timebase secondary: A timing system established from an alternate source when the primary
source is not available.
2.79 time-of-use register: That portion of a watthour meter that, for selected periods of time,
accumulates and may display amounts of electric energy, demand, or other quantities measured or
calculated.
2.80 time-of-use register – period: A selected period of time during which a specified rate will apply to
the energy usage or demand, typically designated as A, B, C, and D.
2.81 time-of-use register – switch point: The transition from one time-of-use period to another.
2.82 total harmonic distortion (THD): The ratio of the root-mean-square of the harmonic content
(excluding the fundamental) to the root-mean-square value of the fundamental quantity, expressed
as a percentage.
2.83 totalizing: A device used to receive and sum pulses from two or more sources for proportional
transmission to another totalizing relay or to a receiver.
2.84 transducer: A device to receive energy from one system and supply energy (of either the same or
of a different kind) to another system, in such a manner that the desired characteristics of the
energy input appear at the output.
2.85 transformer-loss compensation: A method that adds to or subtracts from the meter registration to
compensate for predetermined iron and/or copper losses of transformers and transmission lines.
2.86 varhour meter: An electricity meter that measures and registers the integral, with respect to time, of
the reactive power of the circuit in which it is connected. The unit in which this integral is measured
is usually the kilovarhour.
2.87 varhour test constant: The expression of the relation between the reactive energy applied to the
meter and corresponding value of the test output.
NOTE—For electromechanical meters, one test output equals one disk revolution.
2.88 voltage-withstand tests: Tests made to determine the ability of insulating materials and spacings
to withstand specified overvoltages for a specified time without flashover or puncture.
2.89 watthour meter: An electricity meter that measures and registers the integral, with respect to time,
of the active power of the circuit in which it is connected. The unit in which this integral is measured
is usually the kilowatthour.
2.90 watthour meter – bottom-connected: A meter having a bottom-connected terminal assembly.
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ANSI C12.1-2008
2.91 watthour meter – calibration: Adjustment to bring the percentage registration of the meter to
within specified limits.
2.92 watthour meter – basic reference standards: Those standards with which the value of the
watthour is maintained in the laboratory.
2.93 watthour meter – class designation: The maximum specified continuous load in amperes.
2.94 watthour meter – detachable (socket mounted): A meter having bayonet-type (blade) terminals
arranged on the back side of the meter for insertion into matching jaws of a meter socket (or
detachable meter-mounting device).
2.95 watthour meter – field standard: A portable meter that is used as a standard meter to calibrate
the utility's billing meters and is traceable to NIST. This meter is also known as a portable standard
or working standard.
2.96 watthour meter – form designation: An alphanumeric designation denoting the circuit
arrangement for which the meter is applicable and its specific terminal arrangement. The same
designation is applicable to equivalent meters of all manufacturers.
2.97 watthour meter – full load: Full load is a test condition using test amps, rated voltage and unity
power factor.
2.98 watthour meter – gear ratio (Rg): The number of revolutions of the meter’s rotor for one revolution
of the first dial pointer.
2.99 watthour meter – induction: A motor-type meter in which currents induced in the rotor interact with
magnetic fields to produce the driving torque.
2.100 watthour meter – light load: Light load is a test condition using rated voltage, 10% of test amps
and unity power factor.
2.101 watthour meter – load range: The maximum range in amperes over which the meter is designed
to operate continuously with a specified accuracy.
2.102 watthour meter – multistator: A watthour meter containing more than one stator.
2.103 watthour meter – percentage error: The difference between percentage registration and 100%.
NOTE—A meter whose percentage registration is 95% is said to be 5% slow, or its error is (-) 5%.
2.104 watthour meter – percentage registration: The ratio of the actual registration of the meter to the
true value of the quantity measured in a given time, expressed as a percentage.
2.105 watthour meter – reference performance: test, used as a basis for comparison with
performances under other conditions of the test.
2.106 watthour meter – register: A device for use with an electricity meter that indicates or records units
of electric energy or other quantity measured.
2.107 watthour meter – register constant (Kr): The multiplier used to convert the register reading to
kilowatthours (or other suitable units).
NOTE—This constant takes into consideration the watthour constant, gear ratio, and instrument transformer
ratios.
2.108 watthour meter – register ratio (Rr): The number of revolutions of the first gear of the register for
one revolution of the first dial pointer.
2.109 watthour meter – registration: The amount of electric energy (or other quantity being measured)
that was recorded by the meter.
NOTE—It is equal to the product of the register reading and the register constant. The registration during a
given period is equal to the product of the register constant and the difference between the register readings at
the beginning and the end of the period.
8
ANSI C12.1-2008
2.110 watthour meter – rotor: That part of an induction meter that is directly driven by electromagnetic
action.
2.111 watthour meter – self contained: A meter in which the terminals are arranged for connection to
the circuit being measured without using external instrument transformers.
2.112 watthour meter – single stator: A meter containing only one stator.
2.113 watthour meter – stator: An assembly of an induction watthour meter, which consists of a voltage
circuit, one or more current circuits, so arranged that their joint effect, when energized, is to exert a
driving torque on the rotor.
2.114 watthour meter – transport standard: Standard meters of the same or better level of uncertainty
as the basic reference standard meters that are used for transferring the value of the watthour
between standards.
2.115 watthour meter – test constant (Kt): The expression of the relationship between the energy
applied to the meter and the corresponding occurrence of one test output indication expressed as
watthours per test output indication.
2.116 watthour meter constant (Kh): The expression of the relationship between the energy applied to
the meter and one disk revolution or equivalent, expressed as watthours per revolution or watthours
per equivalent revolution.
9
ANSI C12.1-2008
3.1 Scope
To outline an appropriate chain of intermediate steps between the national standards and watthour meters.
10
ANSI C12.1-2008
NIST
Independent Lab
Transport
Standard
Field/Working/Portable Standard
Customers Meter
It may be equipped and staffed to make calibration tests at some or all of the sequential steps intermediate
between the national standards of resistance, EMF, and time interval, and a local reference standard of
energy measurement (such as a group of watthour meters).
11
ANSI C12.1-2008
12
ANSI C12.1-2008
cause of the variation. If the cause cannot be determined and corrected, use of the standard shall be
discontinued.
3.10.2.1 Insulation
The insulation between current-carrying parts of separate circuits and between current-carrying parts and
other metallic parts shall be capable of withstanding the application of a sinusoidal voltage of 2.3 kV rms, 60
Hz for 1 minute with the leakage current not to exceed 0.005 A per circuit.
3.10.2.2 Accuracy specification for the effect of variation of voltage and current
3.10.2.2.1 Reference conditions
Voltage 120V
Current 5.0 A
Frequency 60 Hz
Power Factor Unity and 0.5 Lagging
o
Temperature 23 C
13
ANSI C12.1-2008
Percent Error
Standards
@ 1.00 PF @ 0.5 PF
Portable Standard 0.1% 0.2%
Reference Standard 0.05% 0.1%
14
ANSI C12.1-2008
4.1 General
15
ANSI C12.1-2008
4.3.1 Sealing
Metering devices shall be provided with facilities for sealing to detect unauthorized entry.
4.3.2 Enclosures
The enclosure, if intended for indoor application, shall meet the performance specifications described in
NEMA 250, for Type 2 enclosures.
The enclosure, if intended for outdoor application, shall meet the performance specifications described in
NEMA 250, for Type 3R enclosures.
16
ANSI C12.1-2008
4.5.2 Configuration
Metering devices shall be complete assemblies.
17
ANSI C12.1-2008
4.6.1 Tolerances
Due to possible errors in observations and in the test equipment employed, a tolerance should be applied to
the specified limits of percent deviation for any test condition involving a determination of the accuracy of the
metering device. A metering device shall be considered to be within the allowable limits if the measured
deviation does not exceed the specified maximum deviation from reference performance by 0.1% or by one
tenth of the maximum deviation, whichever is greater. The above reference points shall be as close as
practical to zero error and in no case shall exceed 0.5% error.
4.6.2.1 Failure
A test metering device shall be designated as failed if any of the following events occur during or after any
certification test:
4.6.2.1.1 Failure of the metering device to perform all functions as specified in a valid test procedure
(4.7.2.1 – 4.7.2.14 and 4.7.3.1 – 4.7.3.24).
4.6.2.1.2 The metering device has signs of physical damage as a result of a test procedure.
4.6.2.1.3 The metering device fails to remain within accuracy limits of a valid test procedure, either as
defined by the test procedure, or as the result of the Accuracy Performance Check as defined in 4.7.3.
4.6.2.2 Meter Type Certification Rejection Criteria
The meter type certification will be rejected if any of the following events occur:
4.6.2.2.1 The metering devices fail the certification tests as specified in Table 2 below:
18
ANSI C12.1-2008
# METERING
FAILURES IN DIFFERENT TESTS INDIVIDUALLY
DEVICES
TESTED 0 1 2 3 or more
3
4 F A IL
7
PA SS
9 or more
Examples The following examples explain how to apply Table 2. Also, reference to “the series tests“ in this
paragraph means tests required to be performed in the series manner as specified in Section 4.1.6., and
reference to “the parallel tests“ means testing is not required to be performed in any particular sequence
(either series or parallel).
Example 1: If 3 metering devices are selected for the series testing and one failure occurs in any test
procedure, the meter type certification will be rejected and the entire eight series tests will be started over
from the beginning.
Example 2: If 9 metering devices are selected for the series tests and the first, second, and third failures
occur separately in three different tests or test procedures, the meter type certification will be rejected.
These failures described here mean that a failure of the first metering device during one test procedure, a
failure of a second metering device during another test procedure, and a failure of a third metering device
during another test procedure different from the tests that the first two metering devices have failed
previously. Once such failures occur, the entire eight series tests will be started over from the beginning.
However, if 3 metering devices are selected for a parallel test performed concurrently with the 9 metering
devices selected for the series tests, the rejection criteria for the 3 metering devices tested in a parallel test
shall not apply to the 9 metering devices tested in series, or vice versa. In addition, if a group of metering
devices tested in a parallel test(s) fails according to the rejection criteria, only the particular failed test(s)
needs to be repeated.
4.6.2.2.2 The failure of two or more metering devices during the same test or test procedure.
Unless otherwise specified, all tests shall be made with the metering device under test mounted in a
conventional manner on a suitably rated meter mounting device (example, socket or load box), free from
vibration. All alternating current tests shall be conducted on a circuit supplied by a sine-wave source with
a distortion factor not greater than 3%. Where the metering device has more than one voltage and current
circuit, it shall be tested with the voltage circuits effectively in parallel and the appropriate current circuit(s)
energized effectively in series, unless otherwise specified. For metering devices with auxiliary devices
19
ANSI C12.1-2008
powered line-to-line, the metering device shall be tested with the voltage and current circuits individually
energized to power the auxiliary device as it would be in normal operation.
o o
All tests shall be made at 23 C 5 C, rated voltage 3%, rated frequency 1 Hz, test amperes 3%,
o
and unity power factor 2 , unless otherwise indicated in specific tests. The metering device shall be
stabilized at ambient temperature before performance tests are made. A list of all the required tests is shown
in Table 3.
20
ANSI C12.1-2008
21
ANSI C12.1-2008
22
ANSI C12.1-2008
23
ANSI C12.1-2008
4.7.2.5.1 Test No. 5a: Effect of variation of voltage on the solid-state auxiliary device
A solid-state auxiliary device can be tested for accuracy of the auxiliary device and its input pulse initiator,
using electromechanical watthour meter disk revolutions as the input source for Test 5a. For testing the
accuracy of the solid-state auxiliary device only, an auxiliary input pulse source may be used, bypassing the
input pulse initiator. A minimum count of 1000 for the measured quantity is required to establish the test
accuracy. The test recognizes the ambiguity of ± 1 least significant digit. This test shall be made with the
solid-state auxiliary device and meter combination energized with rated voltage and rated frequency, at an
ambient temperature of 23 C ± 5 C.
The accuracy of the measured quantities shall not differ from the input source by an amount exceeding that
specified in Table 11.
24
ANSI C12.1-2008
Table 13 – Equality of Current Circuits in the Three-Wire Element for Single-Element Meters
4.7.2.7.2 Multi-element metering device - Equality of current circuits in the three-wire element
In a multi-element, polyphase-metering device, with a three-wire element, the change in performance
produced by using only one current circuit of the three-wire element, as compared with the performance
when both current circuits of the three-wire element are used, shall not exceed the maximum deviation
specified in Table 14. These tests shall be made on each element separately with no current flowing in the
current circuits of the remaining element(s) but with the voltage circuits of all elements energized effectively
in parallel.
25
ANSI C12.1-2008
26
ANSI C12.1-2008
4.7.2.9.1 Test on class 10, 20, 100, 200, and 320 meters
The temperature-rise test shall be made by means of temperature detectors in intimate contact with the
metal of the current circuit and located at its approximate center.
In the case of metering devices provided with terminal compartments (type "A"), the test shall be conducted
under the test conditions specified in 4.7.2.9 until the current-circuit temperatures have stabilized. The
temperature rise shall be considered the difference in degrees Celsius between the stabilized temperature
and ambient (room) temperature.
For detachable metering devices (type "S") Class 100, 200, and 320, the test installation shall be
standardized using a simulated meter as specified in figures 1, 2, and 3. The simulated meter shall have the
same cover and number of current jumper bars as current circuits in the metering device to be tested.
Where the use of “the same cover” of the metering device precludes respecting the height dimension of the
mechanical profile of the simulated meter jumper bars as shown in Figure 1 - Figure 3, the test may be
performed with the minimal amount of bending of the jumper bars necessary to eliminate contact between
the simulated meter jumper bars and the metering device cover, as well as between the simulated meter
jumper bars themselves. A temperature-rise test shall be conducted on the simulated meter by applying the
test current to all jumper bars in series until the temperature as indicated by the temperature detector has
stabilized. This temperature shall then be recorded and the simulated metering device replaced by the
metering device to be tested. When the temperatures of the metering device current circuits have stabilized,
27
ANSI C12.1-2008
the temperatures shall be measured and the empirical temperature-rise values of the meter device current
circuits shall be calculated as follows:
where:
m = Measured final temperature rise of current circuit of metering device under test
s = Measured final temperature rise of current circuit of simulated meter jumper bar for the same
current phase
Rh
T 251 ( 1) for aluminum windings
Rc
where:
T = temperature rise in degrees Celsius
Rh = hot resistance
Rc = cold resistance
To determine the temperature rise at the time of de-energization, the temperature rise corresponding to the
resistance values for each current circuit shall be plotted against time. The graph shall be extrapolated to the
time of de-energization.
28
ANSI C12.1-2008
29
ANSI C12.1-2008
Figure 2 – Dimensions for jumper bars of simulated meter temperature-rise test for
single-phase and polyphase meters (maximum rating 101 – 200 A rating)
30
ANSI C12.1-2008
Figure 3 – Dimensions for jumper bars of simulated meter temperature-rise test for
single-phase and polyphase meters (maximum rating 201 – 320 A rating)
31
ANSI C12.1-2008
32
ANSI C12.1-2008
33
ANSI C12.1-2008
For test conditions (7) through (12) in Table 19, a current shall be applied to Element B. The currents in
Element A and Element B shall be equal in magnitude, and each shall be substantially in phase with the
voltage applied to the respective element. For these test conditions, both the voltage circuit and the current
circuit of Element B shall be connected as follows:
Reference performance — Phase 1 direct
Conditions (7) and (8) — Phase 1 reversed
Conditions (9) and (10) — Phase 2 direct
Conditions (11) and (12) — Phase 2 reversed
For a two-element three-phase four-wire wye metering device, the current circuit common to both elements
shall not be connected. The currents used shall be twice the values indicated in Table 19. The circuits of any
three-wire element shall be connected in series and shall be tested as one circuit.
The difference between the performance of the metering device under the test conditions specified and the
applicable reference performance shall not exceed the maximum deviation in Table 19.
34
ANSI C12.1-2008
For test conditions (5) through (8) in Table 20 current shall be applied to the current circuits of Element B
and Element C.
These currents shall be equal in magnitude with the current applied to Element A, and each shall be
substantially in phase with the voltage applied to the respective element. For these test conditions, both the
voltage and current circuits of Element B and, similarly, the voltage and current circuits of Element C shall be
connected as follows:
Reference performance — Both Element B and Element C, Phase 1 direct
Conditions (5) and (6) — Element B, Phase 2 direct; Element C, Phase 3 direct
Conditions (7) and (8) — Element B, Phase 3 direct; Element C, Phase 2 direct
The difference between the performance of the metering device under the test conditions specified and the
applicable reference performance shall not exceed the maximum deviation in Table 20.
35
ANSI C12.1-2008
The requirement to perform an Accuracy Performance Check before and after each individual test
procedure may be relaxed for the following group of test procedures: Mechanical Shock, Transportation
Drop, Mechanical Vibration, and Transportation Vibration. An Accuracy Performance Check shall be
required before and after this entire group of tests is performed.
36
ANSI C12.1-2008
The standard 0.5 µs – 100 kHz Ring Wave applied to the metering device, shall be for Location Category
B, as described in IEEE C62.41.2-2002, Table 2.
The standard 1.2/50 µs – 8/20 µs combination wave applied to the metering device shall be for Location
Category B, as described in IEEE C62.41.2-2002, Table 3.
37
ANSI C12.1-2008
– Condition (2). Directly behind the center-line of the metering device in a vertical position. The
middle of the conductor shall be 10 inches (254 mm) directly behind the center and on a level
with the center of the metering device. The loop shall be in a vertical plane perpendicular to the
test board.
– Condition (3). Vertically at the same distance in front of the test board as the center of the
metering device. The middle of the conductor shall be on the same level with the center of the
metering device and 10 inches (254 mm) to the right or left. The loop shall be in a vertical plane
parallel to the test board.
For conditions (1) through (3), the change produced in the performance of a metering device by application
of a 100 ampere-turn external magnetic field shall not exceed the maximum deviation specified in Table 21.
Available nominal voltage and current can be used for the duration of this test except when the metering
device is undergoing the specified accuracy test.
– Conditions (7) through (12). Repeat conditions (1) through (6), respectively, except that
metering devices shall be placed in a space having a temperature of -20 C 5 C. The effect of
variation of temperature upon the performance of the metering devices shall not exceed the
maximum deviation specified in Table 22. Available nominal voltage and current can be used
for the duration of this test except when the metering device is undergoing the specified
accuracy test.
38
ANSI C12.1-2008
The time, program and register reading requirement of 4.7.3 shall not apply.
* When the actual temperature difference between two tests differs from the nominal temperature difference
specified for the two tests, the deviation shall be adjusted proportionally.
39
ANSI C12.1-2008
4.7.3.5.1 Test No. 19a: Effect of variation of ambient temperature on the solid-state auxiliary
device
A solid-state auxiliary device can be tested for accuracy of the auxiliary device and its input pulse initiator,
using electromechanical watthour meter disk revolutions as the input source for Test 19a. For testing the
accuracy of the solid-state auxiliary device only, an auxiliary input pulse source may be used, bypassing the
input pulse initiator. A minimum count of 1000 for the measured quantity is required to establish the test
accuracy. The test recognizes the ambiguity of ±1 least significant digit.
This test shall be made with the solid-state auxiliary device and meter combination energized with rated
voltage and rated frequency. The auxiliary device, while energized, shall be exposed to each specific test
temperature for at least two hours prior to the test. The accuracy of the measured quantities shall not differ
from the input source by an amount exceeding that specified in Table 23.
40
ANSI C12.1-2008
To meet the mechanical structure requirement of this test, the metering device shall meet the constraint
of 4.6.2.1.2.
To meet the insulation requirement of this test, the metering device shall pass Test No. 15, Insulation,
immediately following the completion of this test. The application of Test No. 15 in this manner shall not
excuse the metering device from the application of this test in the series test sequence.
4.7.3.10 Test No. 24: Effect of variation of ambient temperature-secondary time base
This test shall be conducted with the metering device in the battery carryover mode. The accuracy of the
secondary time shall be within 0.02% (2 minutes per week) at ambient temperatures of -30 C 5 C and
70 C 5 C. The metering device shall be exposed to each specified temperature for not less than 2 hours
prior to testing.
41
ANSI C12.1-2008
This test shall be conducted on all metering devices containing solid-state components excluding LED
voltage indicators. This test may be omitted for electromechanical meters and registers.
0 . 1 M E T E R M I N . (A L L G R O U N D P L A N E E D G E S )
S U R G E D L IN E
1 .0 M E T E R 0 .0 5
N O N -C O N D U C T I V E S U P P O R T
H IG H F R E Q . G R O U N D S U C H
A S 2 5 m m B R A iD E D S T R A P
H IG H F R E Q . G R O U N D S U C H
A S 2 5 m m B R A ID E D S T R A P
POW ER RETURN
1 .0 M E T E R 0 .0 5 0 .1 M E T E R
1 – E Q U IP M E N T O N G R O U N D P L A N E M U S T B E 0 . 5 M E T E R
F R O M O T H E R C O N D U C T IV E S T R U C T U R E S .
2 – L E A D S M U S T B E K E P T A M IN I M U M O F 0 . 1 M E T E R A B O V E
GROUND PLANE.
3 – G R O U N D P L A N E M U S T B E A M IN I M U M O F 1 . 0 M E T E R x
1 . 0 M E T E R W IT H A T L E A S T 0 . 1 M E T E R O F G R O U N D
P L A N E E X T E N D IN G B E Y O N D A L L E Q U IP M E N T O N T H E
GROUND PLANE.
4 - S U R G E A N D P O W E R R E T R N L IN E S M A Y E G R E S S T H E
M E T E R S O C K E T T H R O U G H A N Y P O IN T .
42
ANSI C12.1-2008
The metering device shall meet the Electrical Oscillatory SWC Test requirements of IEEE 37.90.1. This
test subjects the power inputs and the I/O circuits of the metering device to repetitive bursts damped
oscillatory waves with an initial crest of 2.5 kV for a duration of 2 minutes.
The test shall be conducted utilizing the test equipment configurations and test conditions specified in
IEEE C37.90.1. The application points shall be Current, Voltage, Power supply, Input circuit, output, Data
communications and Signal circuit as defined in ANSI/IEEE C37.90.1-2002, and be per Table 26 below.
In addition to the definitions of these terms in ANSI/IEEE C37.90.1-2002, “Data communications” and
“Signal circuit” shall be defined for a metering device as follows:
Data communications shall include: TIP and Ring on an output from a Modem, any RS232/485
lines, plus any other communications type output/inputs. The application of the waveform would
be capacitively coupled to the lines. These lines shall not be considered as “Input circuit” or
“Output”, requiring a direct application to the ports.
Signal circuit shall include: KYZ outputs, KYZ inputs, customer alert lines, EOI outputs, EOI
inputs, plus others. The application of the waveform would be capacitively coupled to the lines.
These lines shall not be considered as “Input circuit” or “Output”, requiring a direct application to
the ports.
43
ANSI C12.1-2008
Table 26 – Test Modes, Voltage, and Application for Each External Connection
Group—Oscillatory Test
Oscillatory
Applicatio
Test modes test Voltage
External n
to be applied
connection group
Common Transverse
This test shall be conducted on all metering devices containing solid-state components excluding LED
voltage indicators. This test may be omitted for electromechanical meters and registers.
44
ANSI C12.1-2008
to allow both horizontal and vertical irradiation of the front, left side, right side, top, and bottom of the test
sample.
Below 1 GHz, the signal shall be 90% amplitude modulated with a 1.0 kHz sine wave. A continuous wave
signal is used above 1 GHz. Beginning at 200 kHz, the scan rate will double the frequency no faster than
every 200 seconds (.005 octaves/second) through 10 GHz.
One test sample is used to determine the orientation which provides the greatest sensitivity.
With a field strength set to 15 +/- 5 V/m, test the test samples over a frequency range in the most sensitive
orientation.
In each orientation above, the fixture shall place the test sample in a test volume in which the field strength
remains within acceptable test limits.
When using GTEM testing, power and I/O leads should be only as long as needed to make connection from
the GTEM shielded I/O connectors to the test sample. Leads shall not exceed 5 meters in length. Excess
leads shall be coiled in a 0.4 meter diameter coil and supported 0.02 to 0.1 meter off the floor and other
metal surfaces of the GTEM.
4.7.3.13 Test No. 27: Radio frequency conducted and radiated emission test
The metering device shall conform to all applicable requirements of the Code of Federal Regulations (CFR)
47, Part 15—Radio Frequency Devices, Subparts A—General and B—Unintentional Radiators issued by the
Federal Communications Commission for Class "B" digital devices.
The test shall be conducted with all cables connected, with all options and accessories specified, in a
configuration closely resembling typical field in-service connections. Typical in-service configurations are
provided in Figures 6, 7, 8, and 9. These figures shall be followed as closely as possible, appropriate to the
type of meter tested and test chamber utilized for the test. The LISN can be optionally located on the floor.
For all other aspects of this test not covered by CFR 47, Part 15 A and B, and this standard, refer to ANSI
C63.4.
This test shall be conducted on all metering devices containing solid-state components excluding voltage
indicators. This test may be omitted for electromechanical meters and registers.
The time, program and register reading requirement of 4.7.3 shall not apply.
45
ANSI C12.1-2008
SHIELDED ANTENNA
ENCLOSURE
RF
FRONT VIEW
Figure 6 – Typical test layout for radiated susceptibility—Test 26 and radiated and conducted
emissions—Test 27. Reference 4.7.3.12.1 and 4.7.3.13
46
ANSI C12.1-2008
LINE CONDUCTORS
4 INDIVIDUAL CONDUCTORS
#14 AWG, TYPE THHN OR EQUIVALENT
3.5 METERS IN LENGTH
UNSHIELDED AND NOT TWISTED
HOT
LISN *
TO
VOLTAGE
SUPPLY
LISN *
NEUTRAL
EACH END TO BE
INSULATED
4 INDIVIDUAL CONDUCTORS
#14 AWG, TYPE THHN OR EQUIVALENT
3.0 METERS IN LENGTH * LINE IMPEDENCE STABILIZATION
UNSHIELDED AND NOT TWISTED NETWORK
LOAD CONDUCTORS
Figure 7 – Typical wiring detail for self contained meters for radiated susceptibility —Test 26 and
radiated and conducted emissions —Test 27. Reference 4.7.3.12.1 and 4.7.3.13
47
ANSI C12.1-2008
TERMINATION
RESISTORS
INDIVIDUAL CONDUCTORS (AS REQ'D) 2 EACH
#16 AWG, TYPE THHN OR EQUIVALENT 20K TYPICAL
5.0 METERS IN LENGTH
UNSHIELDED AND NOT TWISTED
I/ O CONDUCTORS
SPLICE LINE & LOAD CONDUCTORS
TOGETHER & GROUND TO
SIMULATE LOOPS FORMED BY
CURRENT CIRCUITS IN ACTUAL
INSTALLATIONS
3 INDIVIDUAL CONDUCTORS
#14 AWG, TYPE THHN OR EQUIVALENT
3.0 METERS IN LENGTH
UNSHIELDED AND NOT TWISTED * LINE IMPEDANCE STABILIZATION
CURRENT CIRCUIT LOAD CONDUCTORS NETWORK
Figure 8 – Typical wiring detail for transformer rated meters for radiated susceptibility —Test 26
and radiated and conducted emissions —Test 27.
Reference 4.7.3.12.1 and 4.7.3.13
48
ANSI C12.1-2008
SEPTUM HEIGHT
SEPTUM
ANECHOIC
ABSORBERS
METER
TO SIGNAL GEN.
Figure 9 – Typical GTEM test layout for Radiated Susceptibility Test.— Reference 4.7.3.12
NOTES —
1 Uniformity of the test field shall be demonstrated to ensure field does not fall below minimum field requirements.
2 All power and cabling exiting the enclosure shall be suitably filtered to prevent RF leakage.
3 Orientation of the test meter is shown for front, horizontal polarization.
4 Field intensity is controlled by septum voltage (direct measurement), or by field probes located in the cell.
5 Field strength shall be determined from the central axis of the meter : voltage on septum divided by septum
height equals field strength.
Discharges shall be applied only to such points and surfaces of the metering device that are normally
accessible with the cover (and terminal compartment cover when applicable) in place. Discharges shall not
be applied to any point that is accessible only for maintenance purposes, including, but not limited to, the
meter terminals or the conductors connected to the terminals.
This test shall be conducted on all metering devices containing solid-state components excluding voltage
indicators.
An Accuracy Performance Check shall be performed (4.7.3).
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ANSI C12.1-2008
– The metering device enclosure door or cover shall be closed (normal operating position) for the
duration of the test.
– The metering device shall not be powered nor operating for the duration of the test.
– The test duration shall be 168 hours.
– The temperature shall be cycled once each 24 hours, as described below. The temperature
ramping shall be smooth and continuous. The rate of temperature change during ramping shall
not exceed 20 C, per hour.
– The daily temperature cycle shall be conducted as follows:
– Ramp up from room ambient to the Maximum Storage Temperature, Tstor–Max in
approximately 3 hours.
– Soak at TStor–Max for approximately 11 hours.
– Ramp down to Minimum Storage Temperature, Tstor–Min in approximately 6 hours.
– Soak at Tstor–min for approximately 3 hours
– Ramp up to room ambient, in approximately 2 hours
Available nominal voltage and current can be used for the duration of this test when run independent of any
other test.
An Accuracy Performance Check shall be performed (4.7.3).
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ANSI C12.1-2008
Available nominal voltage and current can be used for the duration of this test when run independent of any
other test.
An Accuracy Performance Check shall be performed (4.7.3).
This test follows Test No. 35: Transportation Vibration, and shall be conducted as described as Shock
Testing in the International Safe Transit Association Test Procedure 1A.
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ANSI C12.1-2008
This test exposes the metering device, packaged for shipment, to transportation vibration for
approximately one hour.
This test shall be done on the same metering devices and the same packaging as Test No. 33, and shall be
done before Test No. 33. The metering device, packaged in its intended packing container shall pass the
requirements described as Vibration Testing in the International Safe Transit Association Test Procedure
1A.
After this test, covers, terminal covers, etc. shall be readily removable. There shall be no progressive
corrosion or electrolytic action that will adversely affect the functioning of any part of the meter. Also,
there shall be no evidence of deleterious discoloration or fading of finishes or materials. The time,
program and register reading requirement of 4.7.3 shall not apply.
52
ANSI C12.1-2008
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ANSI C12.1-2008
5.1.1 Purpose
The purpose of this section is to establish accuracy limits, test plans, and inspection procedures for
alternating-current revenue watthour meters.
Watthour meters placed into service or returned to service shall meet the provisions as set forth in this
Section.
All watthour meters and their associated equipment shall be thoroughly inspected at the time of installation
to assure safe and accurate operation.
5.1.3 Tests
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5.1.4.1 General
The performance of watthour meters should be verified by an annual test program such as one of the three
plans listed below. Records shall be maintained on each watthour meter tested. Subsequently, an analysis
of the test results for each group of watthour meters shall be made and appropriate action shall be taken.
The generally accepted plans for testing are:
a) Periodic interval plan
b) Variable interval plan
c) Statistical sampling plan
5.1.4.2 Objectives
The primary purpose of performance testing is to provide information on which the utility may base a
program to maintain meters in an acceptable degree of accuracy throughout their service life.
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0–3% 12.5%
> 3% 25.0%
The minimum number of meters to be tested in each group shall be 200 meters or 12.5% of that group,
whichever is less.
5.1.4.3.3 Statistical sampling plan
The statistical sampling plan used shall conform to accepted principles of statistical sampling based on
either variables or attributes methods. Meters shall be divided into homogeneous groups, such as
manufacturer and manufacturer's type. The groups may be further divided into subdivision within the
manufacturer's type by major design modifications.
NOTE—Examples of statistical sampling plans can be found in ANSI/ASQC Z1.9, the ANSI version of MIL-STD-414 and
ANSI/ASQC Z1.4, the ANSI version of MIL-STD-105.
5.1.5.1 Method 1
Average percentage registration is the weighted average of the percentage registration at light load (LL) and
at full load (FL), giving the full load registration a weight of four. By this method
Average percentage registration = 4FL + LL
5
5.1.5.2 Method 2
Average percentage registration is the average of the percentage registration at light load (LL) and at full
load (FL). By this method
Average percentage registration = FL + LL
2
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5.1.5.3 Method 3
Average percentage registration is the registration at a single point when this single point represents the
registration within the load range.
5.1.5.4 Method 4
Average percentage registration for Polyphase meters is the weighted average of the percentage
registration at light load (LL), Full Load (FL), and Power Factor (PF), giving the full load registration a weight
of four, and the light load registration a weight of two. By this method.
Average percent registration = 4FL + 2 LL + PF
7
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5.3.3.2 Inspection
When metering installations are inspected the instrument transformers associated with the installations
should receive a close visual inspection for correctness of connections and evidence of any damage.
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6.1 General
The usual form of pulse initiators is that of an attachment to a meter device so arranged that the number of
pulses produced is proportional to the quantity measured.
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All tests shall be made at 23 C 5 C, rated voltage 3%, rated frequency 1 Hz, test current 3%, and unity
power factor 2%, unless otherwise indicated in specific tests. The metering device shall be stabilized at
ambient temperature before performance tests are made.
After each test, a sufficient time interval shall be allowed for the pulse device to come to a stable condition
before making the next observation or test.
6.3.4 Insulation
With the meter device voltage and current circuits de-energized, the insulation between current carrying
parts of separate circuits and between current-carrying parts and other metallic parts shall be capable of
withstanding the application of a sinusoidal voltage of 2.5 kV rms, 60 Hz for 1 minute. The input circuit of the
pulse initiators with independent power supplies power supply shall be tested at 1.5 kV rms, 60 Hz for one
minute. The leakage current shall not exceed 0.005 A per circuit. For both the 1.5 and 2.5 kV rms test, low-
voltage electronic circuits, operating at less than 40 V rms, and all output relay terminals, shall not be
subjected to this test.
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APPENDIX A
(Informative)
Measurement of Power, Energy, and Related Quantities
A.1.1 Introduction
The growth in the use of electric power and energy has made necessary the adoption of polyphase
alternating-current transmission and distribution systems. Such a system is a circuit or network to which are
applied two or more voltages of the same frequency but displaced in phase by a fixed amount relative to one
another. The individual circuits making up the polyphase network are called phases. The correct
measurement of power, energy, and related quantities in polyphase circuits requires the proper selection
and application of meters and meter elements. It is not the intention to present in this standard a complete
test of all the methods of measurement of power and energy. The material contained herein is intended to
cover the basic methods of measurement of power, energy, and related quantities as accomplished by
acceptable commercial practice.
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A.2.7.1. However, if the voltages between each line and neutral are balanced within acceptable limits, the
accuracies generally are considered to be satisfactory. Such a meter has one voltage coil and a two-section
current winding on each stator. This winding consists of two coils wound in opposite directions on a common
core. Thus when each of the coils is connected in its respective circuit, the magnetic effects of the currents
in the two sections of the winding are additive. These windings are connected as follows: One current coil of
the first stator is inserted in one line conductor and its flux reacts with the flux of the voltage coil connected
between that conductor and the neutral. Similarly, one current coil of the second stator is inserted in another
line conductor and its flux reacts with the flux of the voltage coil connected between that conductor and the
neutral. The remaining current coils, one on each stator, are connected in series and inserted in the
remaining phase conductor.
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modern materials and techniques are designed to function satisfactorily over a very wide load range. For
these meters the terms nominal or rated load, or some multiple or fraction thereof, have no specific meaning.
As a result, present-day practice classifies such a meter as Class 100 or Class 200. This means that a Class
100 meter is designed to operate continuously with acceptable accuracy up to a maximum current of 100 A,
and a Class 200 meter to 200 A.
Since, however, this maximum current is not a suitable value to use when calibrating or testing a meter, the
manufacturer designates the recommended value of amperes, called the `test amperes,' to be used when
calibrating the meter. For example, a Class 100 meter might have a test-ampere designation of 15 A,
abbreviated as `TA 15,' and a Class 200 meter might have a TA 30 nameplate rating. Because modern
meters are frequently required to perform with acceptable accuracies at values of current, voltage, and
frequency, that may differ appreciably from those used to calibrate the meter, compensating devices have
been developed to maintain, within acceptable limits, the calibration accuracy at the calibrating points and
over wide variations therefrom. Moreover, such devices are used to compensate for environmental
conditions, such as changes in ambient temperature, and for other conditions that are not always ideal. No
compensating device is perfect, but all in current use perform well within acceptable limits.
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in all modern meters. It may be assumed with confidence that all modern meters will function satisfactorily
under all reasonable variations in ambient temperature.
A.2.11.6 External Magnetic Fields
In all well-designed induction watthour meters, the arrangement, number, and configuration of the various
electromagnet and permanent-magnet circuits, as well as the number and arrangement of the several coils,
are such as to keep the detrimental effect of the external magnetic fields to a minimum. However, care
should be exercised not to place the meter in a strong varying magnetic field of the same frequency as the
rated frequency of the meter.
A.2.11.8 Surges
Meters installed in rural areas are more exposed to the elements than those in the more congested urban
areas. As a result, atmospheric electrical disturbances have a greater opportunity to affect adversely the
proper functioning of such meters. These disturbances are capable of producing, under certain
circumstances, very large currents of short duration, called surge currents. These currents may go to ground
through or in the vicinity of the meter. When this happens, the excessively large magnetic field created may
affect the strength of the permanent magnets in the meter, thereby resulting in registration errors.
Present-day permanent magnets are designed to have a very strong ability to resist demagnetization. Thus,
with modern meters, over-registration caused by surge currents is a rare occurrence.
In addition to surge proofing of the permanent magnets, a modern meter has built-in surge proofing for its
insulation. For both voltage and current coils, built-in protective gaps to ground are used. In addition, the
voltage coil has increased surge resistance across the coil.
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P
power factor
P2 Q2
where:
P = active power
Q = reactive power
NOTE—The above formula applies only to sinusoidal waveforms without harmonic content.
The quantity thus defined is not, in general, equal to the average value of the power factor during the
interval, but may be referred to as the interval power factor.
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APPENDIX B
(Normative)
Standards and Standardizing Equipment
B.1 General
The purpose and scope of this section is to specify the standards of electrical measurement and of time
interval to which the metering of electric energy shall be referred, and to outline an appropriate chain of
intermediate steps between the national standards of measurement and the watthour meters used in the
meter shop.
B.2.1.1 “The unit of electrical resistance shall be the ohm, which is equal to one thousand million units of
resistance in the centimeter-gram-second system of electromagnetic units.”
B.2.1.2 “The unit of electric current shall be the ampere, which is one-tenth of the unit of current in the
centimeter-gram-second system of electromagnetic units.”
B.2.1.3 “The unit of electromotive force (emf) and of electric potential shall be the volt, which is the
electromotive force that, steadily applied to a conductor whose resistance is one ohm, will produce
a current of one ampere.”
B.2.1.4 “The unit of electric quantity shall be the coulomb, which is the quantity of electricity transferred by
a current of one ampere in one second.”
B.2.1.5 “The unit of electrical capacitance shall be the farad, which is the capacitance of a capacitor which
is charged to a potential of one volt by one coulomb of electricity.”
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B.2.1.6 “The unit of electrical inductance shall be the henry, which is the inductance in a circuit such that
an electromotive force of one volt is induced in the circuit by variation of an inducing current at the
rate of one ampere per second.”
B.2.1.7 “The unit of power shall be the watt, which is equal to ten million units of power in the centimeter-
gram-second system, and which is the power required to cause an unvarying current of one
ampere to flow between points differing in potential by one volt.”
B.2.1.8 “The units of energy shall be (a) the joule, which is equivalent to the energy supplied by a power of
one watt operating for one second, and (b) the kilowatthour, which is equivalent to the energy
supplied by a power of one thousand watts operating for one hour.”
B.2.1.9 The unit of time interval is the atomic second, defined in 1967 by international agreement as a
certain number of periods of a specified atomic transition of cesium 133.
1
Guidelines for implementing the New Representations of the Volt and Ohm Effective January 1, 1990,
NIST Technical Note 1263, June 1989.
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high accuracy (much better than one part in a million), and are appropriate to use without corrections in
verifying the rate of a laboratory standard clock or other reference interval timer.
NIST
Independent Lab
Transport
Standard
Field/Working/Portable Standard
Customers Meter
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It may be equipped and staffed to make calibration tests at some or all of the sequential steps intermediate
between the national standards of resistance, emf, and time interval, and a local reference standard of
energy measurement (such as a group of watthour meters).
2
NCSL RP-10-1991 Establishment and Operation of an Electrical Utility Metrology Laboratory,
Recommended Practice, National Conference of Standards Laboratories.
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say 40%. Any system that controls laboratory humidity within specified upper and lower limits should be
designed to avoid excessive humidity in the event of the failure of the control element.
B.6.2.1 Intercomparison
Ideally, the basic reference standards of a laboratory should be maintained in groups of three or more
separate individual units that can be intercompared readily, since three is the minimum number of units for
which a change in one of them can be both detected and located by intercomparison.
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In some cases, specially calibrated transport standards are used in a Measurement Assurance Program
(MAP) to aid in the achievement of measurement quality control and to link the measurements in the
laboratory to national standards.
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– It shall be designed to avoid or minimize changes in ratio resulting from self-heating at rated
voltage or from ambient temperature changes.
B.6.8.1 Stability
The transfer characteristics of an ac-dc transfer standard (that is, its ac-dc differences) are functions of its
geometry, its electrical parameters, and its operating level, and should not change significantly with time.
Hence, the transfer characteristics of an instrument need be determined infrequently, unless the
components of its measuring circuit are modified or replaced, or their physical arrangement altered.
However, the dc calibration of a transfer instrument should be verified periodically.
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B.12.1 General
B.12.1.3 Tolerances
The standard meter under test shall be considered to be within the specified limit unless the test result
exceeds the limit by more than the value of the measurement uncertainty assigned to cover the possible
errors in the laboratory reference standards, observations, and procedures.
B.12.2.1 General
All parts that are subject to corrosive influence under normal working conditions shall be effectively protected
against corrosion due to atmospheric causes. Any protective coating shall not be liable to damage by
ordinary handling or injuriously affected by exposure to air under ordinary conditions. The construction of the
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meter shall be suitable for its purpose in all respects, and shall give assurance of permanence in all
mechanical, electrical, and magnetic adjustments.
B.12.2.4 Case
The case shall be of sufficient strength to afford to the working parts adequate protection against damage
under normal conditions of handling, usage, and transport; and it shall afford to the interior substantial
protection against the entry of dust. Portable standard meters should be fitted with a detachable cover to
enclose the readout, terminals, and controls, and be equipped with a substantial carrying strap. The inside of
the cover should include a means for attaching a calibration card.
B.12.2.5 Sealing
Provision shall be made for the sealing of the standard meter to detect unauthorized access to working parts
and to electrical and magnetic adjusting devices.
B.12.2.6 Window
A window of glass or other suitable transparent material shall be provided to permit a clear view of the
readout. It shall be substantially dust tight and shall be replaceable.
B.12.2.7 Terminals
Terminal identification shall be adjacent to each terminal and shall be of a permanent nature.
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B.12.2.11 Nameplate
A nameplate shall be provided on the outside of the case to show all necessary information, including
manufacturer, type, serial number, voltage ratings, current ratings, frequency, model number, and watthour
constant (Kh) or energy constant (Ke) at basic voltage and current ratings.
B.12.3.1 General
All parts that are subject to corrosive influence under normal working conditions shall be effectively protected
against corrosion due to atmospheric causes. Any protective coating shall not be liable to damage by
ordinary handling or injuriously affected by exposure to air under ordinary conditions. The construction of the
meter shall be suitable for its purpose in all respects, and shall give assurance of permanence in all
mechanical, electrical, and magnetic adjustments.
B.12.3.4 Case
The case shall be of sufficient strength to afford to the working parts adequate protection against damage
under normal conditions of handling, usage, and transport; and it shall afford to the interior substantial
protection against the entry of dust.
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B.12.3.5 Sealing
Provision shall be made for the sealing of the standard meter to detect unauthorized access to working parts
and to electrical and magnetic devices.
B.12.3.6 Window
A window of glass or other suitable transparent material may be provided, if applicable, to permit a clear
view of the readout. It shall be substantially dust-tight and shall be replaceable.
B.12.3.7 Terminals
Terminal identification shall be adjacent to each terminal and shall be of a permanent nature.
B.13.1.4 Frequency
The frequency shall be 60 Hz and be constant to within 0.2%.
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B.13.1.7 Level
Standard watthour meters of the induction type shall be level to within 0.5 .
B.13.1.9 Insulation
The insulation between current-carrying parts of separate circuits and between current-carrying parts and
other metallic parts shall be capable of withstanding the application of a sinusoidal voltage of 2.3 kV rms, 60
Hz, for 1 minute.
B.13.2.1 Drift
Test Condition (1): With 250% rated current and with the voltage circuit open, the indication shall not change
perceptibly in 1 min.
Test Condition (2): With 100% rated current, the braking device on standard watthour meters of the
induction type shall immediately release the rotor when 70% rated voltage is applied.
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Test Conditions
% Maximum
Test %V %I PF Other Deviation
100 100 1.0 0
Reference Conditions
100 25 1.0 0
B.13.1
100 100 0.5 0
Drift
open 250 — see text 0 in 1 min.
B.13.2.1
100 50 1.0 0.25
Current Variation
100 200 1.0 0.25
B.13.2.2
100 50 0.5 0.40
B.13.2.3
100 200 0.5 0.60
90 25 1.0 0.20
110 25 1.0 0.20
Voltage Variation 90 100 1.0 0.20
B.13.2.4 110 100 1.0 0.20
90 100 0.5 0.40
110 100 0.5 0.40
100% on all
100 1.0 0.20
Current Ranges Current Ranges
B.13.2.5.1 100% on all
100 0.5 0.20
Current Ranges
100% on all
100 1.0 0.20
Voltage Ranges Voltage Ranges
B.13.3.5.2 100% on all
100 0.5 0.25
Voltage Ranges
see text
100 100 1.0 0C 0.30
Ambient Temperature
100 100 0.5 0C 0.50
B.13.2.6
100 100 1.0 50 C 0.30
100 100 0.5 50 C 0.50
Internal Heating 100 100 1.0
see text 0.20
B.13.2.7 100 100 0.5
Tilt 100 25 1.0 0.20
see text
B.13.2.8 100 100 1.0 0.20
Repeatability 100 25 1.0 0.20
see text
B.13.2.9 100 100 1.0 0.20
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Test Conditions
% Maximum
Test %V %I Pf Other Deviation
100 100 1.0 0
Reference Conditions
100 25 1.0 0
B.13.1
100 100 0.5 0
100 90 1.0 0.10
Current Variation
100 110 1.0 0.10
B.13.3.2
100 90 0.5 0.10
B.13.3.3
100 110 0.5 0.10
90 100 1.0 0.10
Voltage Variation 110 100 1.0 0.10
B.13.3.4 90 100 0.5 0.15
110 100 0.5 0.15
100% on all
100 1.0 0.10
Current Ranges Current Ranges
B.13.3.5.1 100% on all
100 0.5 0.10
Current Ranges
100% on all
100 1.0 0.10
Voltage Ranges Voltage Ranges
B.13.3.5.2 100% on all
100 0.5 0.10
Voltage Ranges
see text
100 100 1.0 11 C 0.10
Ambient Temperature
100 100 0.5 11 C 0.15
B.13.3.6
100 100 1.0 35 C 0.10
100 100 0.5 35 C 0.15
Repeatability 100 25 1.0 0.05
see text
B.13.3.7 100 100 1.0 0.05
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Appendix C
(Normative)
Registering Mechanism and Meter Constants
for Electro-mechanical Meters
C.1 General
Descriptions have been given of methods for determining the accuracy of a meter as far as the speed of the
rotor is concerned, and for physically checking register and gear ratios. It is equally important that it be
determined mathematically that the relations between the register (dial) constant, watthour constant, register
ratio, and gear ratio are correct. The register constant shall always appear on the face of the register when
other than one, the register ratio will be found marked on the register or on the nameplate, and the watthour
constant usually will be found marked on the nameplate. Manufacturers generally use one standard shaft
reduction for all ratings of meters of the same type, but the information does not appear on the meter. The
gear ratio is dependent on the shaft reduction and also the register ratio. The gear ratio information also
does not appear on the meter.
C.2 Symbols
Kh (watthour constant): The number of watthours per revolution of the meter rotor (disk).
Kr (register, or dial, constant): The multiplier used to convert the register reading to kilowatthours.
Rg (gear ratio): The number of revolutions of the rotor (disk) for one revolution of the first dial pointer.
Rr (register ratio): The number of revolutions of the first gear of the register for one revolution of the first dial
pointer.
Rs (shaft reduction): The number of revolutions of the meter rotor (disk) for one revolution of the first gear of
the register.
C.4 Formulas
When the register constant (Kr), watthour constant (Kh), and shaft reduction (Rs) are known, the register ratio
(Rr) may be determined by the following formula:
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ANSI C12.1-2008
Rg Rr Rs
K h Rr R s Kh Rg
Kr
10 1000
, 10,000
Kr 10 1000
,
Kh
Rr R s
Kr 10 1000
,
Rs
Kh Rr
In the foregoing formulas, 10 is the numerical value of one revolution of the first dial pointer.
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APPENDIX D
(Informative)
Periodic Testing Schedule
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APPENDIX E
(Normative)
Phase-Shifting Transformers
E.1 Definition
For definition of a phase-shifting transformer, see Section 2.
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APPENDIX F
(Informative)
Historical Background
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Committee Personnel
AEIC NELA
J. W. Cowles, Chairman G. A. Sawing, Chairman
O. J. Bushnell W. H. Fellows
G.R. Green W.E. McCoy
J. T. Hutchings
S. G. Rhodes
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This Code, as revised, was submitted in galley-proof form to all the members of the Sectional Committee for
final approval by letter ballot, and it was then formally approved by each of the sponsors. The sponsors,
acting jointly, presented the Code to the American Engineering Standards Committee for approval as
American Standard, and it was so approved February 20, 1928.
Committee Personnel
The Sectional Committee was formally organized March 14, 1924; J. Franklin Meyer, Chairman; E. D. Doyle,
Secretary, later succeeded by H. Koenig.
The actual revision of the Code was done by four technical subcommittees, as authorized by the Section
Committee. These subcommittees were:
(1) Acceptance Specifications: F.V. Magalhaes, Chairman; A. J. Allen, W.M. Bradshaw,
H.B. Brooks, O.J. Bushnell, C.J. Clarke, C.I. Hall, F.C. Holtz, C.H. Ingalls, A.E. Knowlton, W.H.
Pratt
(2) Installation and Maintenance Methods: B. Currier, Chairman; A. S. Albright, A. J. Allen,
W.H. Fellows, R.C. Fryer, E.E. Hill, C.H. Ingalls, A.G. Turnbull, W.L. Wadsworth
(3) Standards: E.D. Doyle, Chairman; A.S. Albright, C.J. Clarke, H.G. Hamann, E.E. Hill
(4) Definitions: J.F. Meyer, Chairman; W.H. Fellows, F.C. Holtz, F.A. Kartak, C.H. Sharp
The work of revision was divided into six major sections and was done by the following six subcommittees:
(1) Definitions: R.D. Bennett, Chairman; H.B. Brooks, P.G. Elliott, W.H. Fellows, R.E. Johnson,
E.E. Kline, W.H. Pratt
(2) Standards and Metering: H.B. Brooks, Chairman; A.S. Albright, W.M. Bradshaw,
F.E. Davis, Jr., F.C. Holtz, H.C. Koenig, G.R. Sturtevant
(3) Specifications for Acceptance of Types of Electricity Meters and Auxiliary Devices: W.C.
Wagner, Chairman; W.M. Bradshaw, H.B. Brooks, A.B. Craig, W.R. Frampton, E.E. Hill, H.C.
Koenig, R.H. Nexsen, W.H. Pratt
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(4) Installation Methods and Watthour Meter Test Methods: O.K. Coleman, Chairman; A.P. Good,
Stanley S. Green, C.B. Hayden, N.S. Meyers, L.D. Price
(5) Laboratory and Service Tests: P.L. Holland, Chairman; J.S. Cruikshank, P.G. Elliott, J.H.
Goss, E.E. Hill, J.C. Langdell, F.L. Pavey
(6) Demand Meters: A.J. Allen, Chairman; F.C. Holtz, R.E. Johnson, E.A. LeFever, R.H. Nexsen,
A.R. Rutter, W.C. Wagner, W.H. Witherow
The work of revision was done by a number of task forces, and was reviewed by the Sectional Committee.
These task forces and their assignments were as follows:
(1) Definitions: W.J. Piper
(2) Measurement of Power and Energy: D.T. Canfield
(3) Standards: F.K. Harris, Chairman; E.F. Blair
(4) Acceptance of New Types of Meters: G.B.M. Robertson, Chairman; T.D. Barnes, E.F. Blair,
J.D. McKechnie, R.A. Road, R.S. Smith
(5) Watthour meter Test Methods: P. W. Hale, Chairman; J. Anderson, T.D. Barnes,
W.C. Downing, Jr., H.W. Kelley, J.D. McKechnie, E.C. Nuesse, R.A. Road, F.H. Rogers
(6) Installation Requirements: H.W. Kelley, Chairman; E.B. Hicks, H.H. Hunter, L.H. Keever,
R.E. Purucker, A.W. Rauth, L..O. Steger
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(7) Instrument Transformers and Auxiliary Devices: J.W. Dye, Chairman; E.F. Blair,
F.R. D'Entremont, B.L. Dunfee, W.H. Farrington, H.W. Kelley
(8) In-Service Tests of Watthour Meters: H.H. Hunter, Chairman; F.K. Harris, A.L. Hobson,
C.L. Lucal, J.D. McKechnie, C.V. Morey, R.E. Purucker, F.H. Rogers, L.O. Steger, G. Wey
(9) Demand Meters (Acceptance, Test Methods, In-Service Tests); G.J. Yanda, Chairman;
R.V. Adams, W.C. Downing, Jr., P. W. Hale, F.M. Hoppe, W.J. Piper, R.A. Road, R.J. Stowel
(10) Editorial: G.B.M. Robertson, Chairman; J. Anderson, P.W. Hale, F.K. Harris, A.T. Higgins, H.H.
Hunter, H.W. Kelley, F.H. Rogers, G.J. Yanda
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The work of revision was done by a number of subcommittees, and was reviewed by the C12 Standards
Committee. The assignments of these subcommittees were as follows:
(1) Definitions, and (2) Measurement of Power and Energy: E.F. Blair, Chairman; R.S. Turgel,
J.M. Vanderleck, A. Yenkelun
(3) Standards and Standardizing Equipment: F.L. Hermach, Chairman; M.F. Borleis,
W.E. Osborn, J. Roth, E.W. Schwarz, D.M. Smith
(4) Acceptance of New Types of Watthour Meters: A. Fini, Chairman; J. Anderson, D.B. Berry,
E.F. Blair, M.F. Borleis, C.R. Colinsworth, F.G. Kuhn, D. McAuliff, G.F. Walsh
(5) Watthour meter Test Methods: F.J. Levitsky, Chairman; J. Anderson, E.F. Blair, T.J. Pearson
(6) Installation Requirements: B.E. Kibbe, Chairman; D. Berry, A. Browne, M.A. Frederickson,
L.M. Holdaway, H.W. Redecker
(7) Instrument transformers and Auxiliary Devices: T.J. Pearson, Chairman; B.L. Dunfee,
F.A. Fragola, J. Landry, R. Stetson
(8) In-Service Tests of Watthour Meters: H.L. Colbeth, Chairman; E.L. Barker, M.A. Frederickson,
J. Keever, J.C. Liewehr, B. Renz, C.F. Riederer, J. Suridis
(9) Demand Meter and Pulse Devices: C.R. Collinsworth, Chairman, E.C. Benbow,
H.A. Duckworth, R. Hopkins, S.C. McColum, C.F. Riederer, C. Ringold, R.J. Stowell,
G.F. Walsh
(10) Editorial: R.A. Road, Chairman; J. Anderson, F.L. Hermach, A.T. Higgins, F.J. Levitsky,
W.E. Osborn, C.F. Riederer
This standard was developed by the American National Standards Committee on Electricity Metering, C12,
for full consensus approval as an American National Standard. Suggestions for improving this standard are
welcome. They should be sent to the American National Standards Institute, 1430 Broadway, New York, NY
10018.
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ANSI C12.1-2008
The Secretariat of the American National Standards Committee C12 on Electricity Metering is held by the
Institute of Electrical and Electronics Engineers and the National Bureau of Standards. At the time this
standard was processed and approved, the C12 Committee has the following members:
R. S. Turgel, Chairman
V. Condello, Secretary
The following Subcommittees of ANSI C12 were actively involved in the revision of this standard. The
assignments of these subcommittees were as follows:
(3) Standards and Standardizing Equipment: R. S. Turgel, Chairman; W. C. Busch,
P. Cunningham, R. E. Koll, F. J. Levitsky, R. H. Stevens
(4) Acceptance of New Types of Watthour Meters: A. Fini, Chairman; J. Anderson,
A. G. Ashenbeck, Jr., D. F. Becker, C. R. Collinsworth
(10) Editorial: F. J. Levitsky, Chairman; C. F. Mueller, A. Loika, R. S. Turgel
This standard was developed by the Accredited Standards Committee on Electricity Metering, C12, for full
consensus approval as an American National Standard. This revised edition supersedes ANSI C12.1-1982.
Suggestions for improving this standard are welcome. They should be sent to the American National
Standards Institute, 1430 Broadway, New York, NY 10018.
The technical content of this standard has been brought up to date, and the changes affect nearly all
chapters. In addition, following IEEE editorial policy aimed at avoiding duplication of similar or identical
requirements in their standards, those sections of text from other IEEE standards that had been
incorporated in the previous edition of C12.1 were replaced by appropriate references to those standards.
The other related standards that the C12 Committee has issued, and is continuing to issue, are listed
3
below:
C12.4-1984, American National Standard for Mechanical Demand Registers.
C12.5-1978, American National Standard for Thermal Demand (R1978) Meters.
C12.6-1987, American National Standard for Marking and Arrangement of Terminals for Phase-Shifting
Devices Used in Metering.
C12.7-1987, American National Standard Requirements for Watthour Meter Sockets.
C12.8-1981, American National Standard for Test Blocks and Cabinets for Installation of Self-Contained
"A" Base Watthour Meters.
C12.9-1987, American National Standard for Test Switches for Transformer-Rated Meters.
C12.10-1988, American National Standard for Watthour Meters.
C12.11-1987, American National Standard for Instrument Transformers for Revenue Metering, 10 kV BIL
Through 350 kV BIL (0.6 kV NSV Through 69 kV NSV).
3
These publications are available from the Service Center, Institute of Electrical and Electronic
Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331, or from the Sales Department,
American National Standards Institute, 1430 Broadway, New York, NY 10018.
103
ANSI C12.1-2008
The Secretariat of the Accredited Standards Committee on Electricity Metering, C12, is held by the Institute
of Electrical and Electronics Engineers and the National Institute of Standards and Technology. At the time
this standard was processed and approved, the C12 Committee had the following members:
R.S. Turgel, Chairman
F. Huber, Jr., Secretary
The following subcommittees of C12 were actively involved in the revision of this standard:
104
ANSI C12.1-2008
L. Struchtemey
G.F. Walsh
In addition to the Committees listed above, C12 also has the following subcommittees:
Subcommittee Chairman
Subcommittee 1 — Definitions (vacant)
Subcommittee 2 — Measurement of Power and Energy (vacant)
Subcommittee 6 — Installation Requirements (vacant)
Subcommittee 9 — Demand Meters (vacant)
Subcommittee 11 — Safety Requirements F. J. Levitsky
Subcommittee 12 — Solid-State Meters D. Dassman
Subcommittee 13 — Time-of-Day Metering T. C. Drew
Subcommittee 14 — Pulse Recorders T. C. Drew
Subcommittee 15 — Watthour Meter Sockets and Test Blocks F. A. Marta
Subcommittee 16 — Solid-State Watthour Meters D. Dassman
105
ANSI C12.1-2008
all metering, while leaving other standards to provide the details for their specific devices, to avoid
duplication. Parts of the existing standard that were viewed as user practices, not standards, were removed
or placed into the appendices as examples or for references.
The Secretariat of the Accredited Standards Committee on Electricity Metering, C12, is held by the National
Electrical Manufacturers Association (NEMA) and the National Institute of Standards and Technology. At the
time this standard was processed and approved, the C12 Committee had the following members:
The following members of the C12 Ad Hoc Committee to Revise C12.1 were actively involved in the
revision of this standard:
T. C. Drew, Chairman
In addition, the following comprised the Editorial Committee for the Revision of C12.1:
G. Belcher
E. Malemezian
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ANSI C12.1-2008
C. J. Smith
R. S. Turgel
The existing standard C12.1 has been rewritten with the intent to bring it up to date in an industry that is
changing dramatically, due to both technology and regulatory matters. The standard has been revised to
form the basic requirement document for all metering devices except instrument transformers. This edition of
the standard has added tests to help insure new electronic equipment is capable of providing the
dependability existing devices have shown.
New to this edition is a methodology for certification of new meter types, which was deemed necessary
because of the more rapid development of meter technology. Other significant additions are specific tests for
meter ancillary devices and tests for wide voltage range meters. Most meter specifications have been
retained from the previous edition without major changes.
The existing standard was broadened to include tests and requirements for all meters, both solid state and
electro-mechanical. Other standards in the C12 series provide the details for their specific devices, thus
avoiding duplication. In addition, an effort was made to align this standard with modern international
standards for electromagnetic compatibility where possible.
The Secretariat of the Accredited Standards Committee on Electricity Metering, C12, is held by the National
Electrical Manufacturers Association (NEMA) and the National Institute of Standards and Technology. At the
time this standard was processed and approved, the C12 Committee had the following members:
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ANSI C12.1-2008
The following members of the C12 Ad Hoc Committee to Revise C12.1 were actively involved in the
revision of this standard:
S. Weikel, Chairman
M. Anderson
J. Arneal
W. Buckley
M. Burns
B. Cook
J. DeMars
W. Germer
C. Gomez
R. Lokys
E. Malemezian
S. Malich
K. McDonald
J. McEvoy
H. Millican
T. Morgan
D. Nguyen
L. Pananen
G. Powers
M. Parc
J. Ruehl
J. Taylor
J Thurber
T. Vahlstrom
S. Weikel
C. S. Weimer
D. Williams
In addition, the following comprised the Editorial Committee for the current Revision of C12.1:
M. Anderson
M. Keys
E. Malemezian
K. Masri
H. Millican
S. Weikel
108