SIST EN 50470-3:2007

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wechselstrom-Elektrizitätszähler -- Teil 3: Besondere Anforderungen - Elektronische Wirkverbrauchszähler der Genauigkeitsklassen A, B und CEquipement de comptage d'électricité (c.a.) -- Partie 3: Prescriptions particulières - Compteurs statiques d'énergie active (classes de précision A, B et C)Electricity metering equipment (a.c.) -- Part 3: Particular requirements - Static meters for active energy (class indexes A, B and C)91.140.50Sistemi za oskrbo z elektrikoElectricity supply systems17.220.20Measurement of electrical and magnetic quantitiesICS:Ta slovenski standard je istoveten z:EN 50470-3:2006SIST EN 50470-3:2007en01-marec-2007SIST EN 50470-3:2007SLOVENSKI
STANDARD



SIST EN 50470-3:2007



EUROPEAN STANDARD EN 50470-3 NORME EUROPÉENNE
EUROPÄISCHE NORM October 2006
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2006 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50470-3:2006 E
ICS 91.140.50
English version
Electricity metering equipment (a.c.)
Part 3: Particular requirements -
Static meters for active energy
(class indexes A, B and C)
Equipement de comptage
d'électricité (c.a.)
Partie 3: Prescriptions particulières -
Compteurs statiques d'énergie active (classes de précision A, B et C)
Wechselstrom-Elektrizitätszähler
Teil 3: Besondere Anforderungen -
Elektronische Wirkverbrauchszähler
der Genauigkeitsklassen A, B und C
This European Standard was approved by CENELEC on 2006-05-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
SIST EN 50470-3:2007



EN 50470-3:2006 – 2 – Foreword This European Standard was prepared by the Technical Committee CENELEC TC 13, Equipment for electrical energy measurement and load control.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50470-3 on 2006-05-01. The following dates were fixed: – latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement
(dop)
2007-05-01 – latest date by which the national standards conflicting with the EN have to be withdrawn
(dow)
2009-05-01 This EN 50470-3 is related to:
– EN 62053-21:2003, Electricity metering equipment (a.c.) – Particular requirements – Part 21: Static meters for active energy (classes 1 and 2) and
– EN 62053-22:2003, Electricity metering equipment (a.c.) – Particular requirements – Part 22: Static meters for active energy (classes 0,2 S and 0,5 S).
The structure of the standards is similar, modifications in this Euroepan Standard are provided in the perspective of compliance with the Essential Requirements of the Directive 2004/22/EC on Measuring Instruments (MID).
This standard is to be used with EN 50470-1:2006, Electricity metering equipment (a.c.) – Part 1: General requirements, tests and test conditions – Metering equipment (class indexes A, B and C). This European Standard has been prepared under a mandate given to CENELEC by the European Commission and the European Free Trade Association and covers essential requirements of EC Directive 2004/22/EC. See Annex ZZ. __________ SIST EN 50470-3:2007



– 3 – EN 50470-3:2006 Contents 1 Scope.5 2 Normative references.5 3 Terms, definitions and abbreviations.5 4 Standard electrical values.6 5 Mechanical requirements.6 6 Climatic conditions.6 7 Electrical requirements.6 7.1 Power consumption.6 7.1.1 Measurement method.6 7.1.2 Voltage circuits.6 7.1.3 Current circuits.6 7.2 AC voltage test.7 8 Accuracy requirements and tests.7 8.1 Limits of percentage error due to variation of the load.7 8.2 Repeatability.8 8.3 Limits of additional percentage error due to influence quantities.8 8.4 Maximum permissible error (MPE).10 8.5 Effect of disturbances of long duration.10 8.6 Short time overcurrents.12 8.7 Performing the tests.12 8.7.1 Accuracy test conditions.12 8.7.2 Accuracy tests at reference conditions.13 8.7.3 Interpretation of accuracy test results.14 8.7.4 Repeatability.14 8.7.5 Test of effects of influence quantities.14 8.7.6 Calculation of the composite error.15 8.7.7 Test of effects of disturbances of long duration.15 8.7.8 Short time overcurrents.18 8.7.9 Test of starting and no-load condition.19 8.7.10 Meter constant.20 9 Durability.20 10 Reliability.20 11 Requirements concerning the software and protection against corruption.21 11.1 General.21 11.2 Identification of functions implemented in software.21 11.3 Identification and protection of software.21 11.4 Identification and protection of metrologically relevant parameters.21 11.5 Setting of parameters.22 11.6 Protection of measurement data.22 11.7 Protection against inadmissible influence by metrologically non-relevant software.22 11.8 Protection against inadmissible influence by connecting another device.22 Annex A (informative)
Calculation of the composite error.23 Annex B (normative)
Test circuit diagram for the test of immunity to earth fault.24 SIST EN 50470-3:2007



EN 50470-3:2006 – 4 – Annex C (normative)
Test circuit diagram for d.c., even harmonics, odd harmonics and sub-harmonics.25 Annex ZZ (informative)
Coverage of Essential Requirements of EC Directives.30 Bibliography.31
Figures Figure B.1 – Circuit to simulate earth fault condition in phase 1.24 Figure B.2 – Voltages at the meter under test.24 Figure C.1 – Test circuit diagram for half-wave rectification.25 Figure C.2 – Half-wave rectified waveform.26 Figure C.3 – Informative distribution of half-wave harmonic content (the Fourier analysis is not complete).26 Figure C.4 – Test circuit diagram (informative).27 Figure C.5 – Phase fired waveform.28 Figure C.6 – Informative distribution of harmonic content of phase fired waveform (the Fourier analysis is not complete).28 Figure C.7 – Burst fired waveform.29 Figure C.8 – Informative distribution of harmonic content of burst fired waveform (the Fourier analysis is not complete).29
Tables Table 1 – Power consumption in voltage circuits.6 Table 2 – Power consumption in current circuits.7 Table 3 – AC voltage tests.7 Table 4 – Percentage error limits at reference conditions (single-phase meters and polyphase meters with balanced loads).8 Table 5 – Percentage error limits at reference conditions (polyphase meters carrying a single-phase load, but with balanced polyphase voltages applied to voltage circuits).8 Table 6 – Limits of additional percentage error due to influence quantities
(single-phase meters and polyphase meters with balanced loads).9 Table 7 – Limits of additional percentage error due to influence quantities (polyphase meters carrying a single phase load,
but with balanced polyphase voltages applied to voltage circuits).9 Table 8 – Maximum permissible error (MPE).10 Table 9 – Effect of disturbances of long duration – Critical change values.11 Table 10 – Effect of short time overcurrents – Critical change value.12 Table 11 – Voltage and current balance.12 Table 12 – Reference conditions.13 Table 13 – Test points determining the intrinsic error and the additional percentage error due to influence quantities.14 Table 14 – Interpretation of test results.14 Table 15 – Starting current.19
SIST EN 50470-3:2007



– 5 – EN 50470-3:2006 1 Scope This European Standard applies to newly manufactured static watt-hour meters intended for residential, commercial and light industrial use, of class indexes A, B and C, for the measurement of alternating current electrical active energy in 50 Hz networks. It specifies particular requirements and type test methods. It applies to static watt-hour meters for indoor and outdoor application, consisting of a measuring element and register(s) enclosed together in a meter case. It also applies to operation indicator(s) and test output(s). If the meter has (a) measuring element(s) for more than one type of energy (multi-energy meters), or when other functional elements, like maximum demand indicators, electronic tariff registers, time switches, ripple control receivers, data communication interfaces etc. are enclosed in the meter case (multi-function meters) then this standard applies only for the active energy metering part. This standard distinguishes between: – meters of class indexes A, B and C; – direct connected and transformer operated meters; – meters for use in networks equipped with or without earth fault neutralizers. It does not apply to: – watt-hour meters where the voltage across the connection terminals exceeds 600 V (line-to-line voltage for meters for polyphase systems); – portable meters; – reference meters. Methods for acceptance testing are covered by the IEC 62058 series of standards 1). The dependability aspect is covered by the documents of the IEC 62059 series. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Publication Year Title EN 50470-1
2006 Electricity metering equipment (a.c.) – Part 1: General requirements, tests and test conditions – Metering equipment (class indexes A, B and C)
EN 62059-41 2006 Electricity metering equipment – Dependability – Part 41: Reliability prediction (IEC 62059-41:2006) 3 Terms, definitions and abbreviations For the purposes of this document, the terms and definitions given in EN 50470-1 apply. ——————— 1) At draft stage. SIST EN 50470-3:2007



EN 50470-3:2006 – 6 – 4 Standard electrical values The values given in EN 50470-1 apply. 5 Mechanical requirements The requirements given in EN 50470-1 apply. 6 Climatic conditions The conditions given in EN 50470-1 apply. 7 Electrical requirements In addition to the electrical requirements in EN 50470-1, meters shall fulfil the following requirements. 7.1 Power consumption 7.1.1 Measurement method The power consumption in the voltage and current circuits shall be determined at reference conditions given in 8.7.1 by any suitable method. The overall maximum error of the measurement of the power consumption shall not exceed 5 %. 7.1.2 Voltage circuits The active and apparent power loss in each voltage circuit of a meter at reference voltage, reference temperature and reference frequency shall not exceed the values shown in Table 1. Table 1 – Power consumption in voltage circuits Meters
(single- and polyphase) Power supply connected to the voltage circuits Power supply not connected to the voltage circuits Power consumption in voltage circuit 2 W and 10 VA 0,5 VA Power consumption of auxiliary power supply -- 10 VA NOTE 1 In order to match voltage transformers to meters, the meter manufacturer should state the power factor of the burden (for transformer operated meters only). NOTE 2 The above figures are mean values. Switching power supplies with peak power values in excess of these specified values are permitted, but it should be ensured that the rating of associated voltage transformers is adequate. NOTE 3 For multifunctional meters see EN 62053-61.
7.1.3 Current circuits The apparent power taken by each current circuit of a meter at reference current, reference frequency and reference temperature shall not exceed the values shown in Table 2. SIST EN 50470-3:2007



– 7 – EN 50470-3:2006 Table 2 – Power consumption in current circuits Class index Meters, (single- and polyphase) Test current A B C Direct connected Iref = 10 Itr 2,5 VA 4,0 VA 4,0 VA Transformer operated In 1,0 VA 1,0 VA 1,0 VA NOTE In order to match current transformers to meters, the meter manufacturer should state the power factor of the burden (for transformer operated meters only).
7.2 AC voltage test The a.c. voltage test shall be carried out in accordance with Table 3. The test voltage shall be substantially sinusoidal, having a frequency between 45 Hz and 65 Hz, and applied for 1 min. The power source shall be capable of supplying at least 500 VA.
For the tests relative to earth, the auxiliary circuits with reference voltage equal to or below 40 V shall be connected to earth. All tests shall be carried out with the case closed and the cover and terminal cover(s) in place. During this test no flashover, disruptive discharge or puncture shall occur. Table 3 – AC voltage tests Test Applicable to Test voltage r.m.s. Points of application of the test voltage 2 kV a) Between, on the one hand, all the current and voltage circuits as well as the auxiliary circuits whose reference voltage is over 40 V, connected together, and, on the other hand, earth. A Protective class I meters 2 kV b) Between circuits not intended to be connected together in service. 4 kV a) Between, on the one hand, all the current and voltage circuits as well as the auxiliary circuits whose reference voltage is over 40 V, connected together, and, on the other hand, earth. B Protective class II meters 2 kV b) Between circuits not intended to be connected together in service.
8 Accuracy requirements and tests 8.1 Limits of percentage error due to variation of the load When the meter is under reference conditions given in 8.7.1, and the current and the power factor are varied, the percentage errors shall not exceed the limits specified for the relevant class indexes in Table 4 and Table 5. If the meter is designed for the measurement of energy in both directions, the values in Table 4 and Table 5 shall apply for each direction. SIST EN 50470-3:2007



EN 50470-3:2006 – 8 – Table 4 – Percentage error limits at reference conditions (single-phase meters and polyphase meters with balanced loads) Percentage error limits
for meters of class index Value of current for direct connected or transformer operated meters Power factor A B C Imin ≤ I < Itr 1 ± 2,5 ± 1,5 ± 1,0 Itr ≤ I ≤ Imax 0,5 ind…1…cap 0,8 ± 2,0 ± 1,0 ± 0,5 NOTE For the relationships Imin / Itr and Imax / Itr see EN 50470-1, Table 3.
Table 5 – Percentage error limits at reference conditions (polyphase meters carrying a single-phase load, but with balanced polyphase voltages applied to voltage circuits) Percentage error limits
for meters of class index Value of current for direct connected or transformer operated meters Power factor A B C Itr ≤ I ≤ Imax 0,5 ind…1 ± 3,0 ± 2,0 ± 1,0 NOTE For the relationship Imax / Itr see EN 50470-1, Table 3.
The difference between the percentage error when the meter is carrying a single-phase load and a balanced polyphase load at Iref and unity power factor shall not exceed 2,5 %, 1,5 % and 1 % for class indexes A, B and C respectively. 8.2 Repeatability The application of the same measurand under the same conditions of measurement shall result in the close agreement of successive measurements. The repeatability at any test point given in Table 13 shall be better than 1/10th of the limit of percentage error at reference conditions. The manufacturer shall state the necessary number of pulses. 8.3 Limits of additional percentage error due to influence quantities When the current and the power factor are held constant at a point within their respective specified measuring ranges, and any single influence quantity is taken from its reference value and varied within its specified operating range, with the meter otherwise operated at reference conditions as specified in 8.7.1, the additional percentage error shall not exceed the limits specified for the relevant class indexes given in Table 6 and Table 7. Concerning additional percentage error due to temperature variation, the requirements for each sub-range within the full temperature range specified by the manufacturer apply. NOTE For example, if the manufacturer specifies that the meter is intended for the temperature range -10 °C to + 40 °C, then the requirements for the sub-ranges 5 °C to 30 °C, -10 °C to 5 °C and 30 °C to 40 °C apply. SIST EN 50470-3:2007



– 9 – EN 50470-3:2006 Table 6 – Limits of additional percentage error due to influence quantities
(single-phase meters and polyphase meters with balanced loads) Limits of additional percentage error for meters of class index Influence quantity Value of current for direct connected or transformer operated meters Power factor A B C Temperature variation
Imin ≤ I ≤ Imax 1 ± 1,8 ± 0,9 ± 0,5 5 °C to 30 °C Itr ≤ I ≤ Imax 0,5 ind, 0,8 cap ± 2,7 ± 1,3 ± 0,9 Imin ≤ I ≤ Imax 1 ± 3,3 ± 1,6 ± 1,0 -10 °C to 5 °C
30 °C to 40 °C Itr ≤ I ≤ Imax 0,5 ind, 0,8 cap ± 4,9 ± 2,3 ± 1,6 Imin ≤ I ≤ Imax 1 ± 4,8 ± 2,4 ± 1,4 -25 °C to -10 °C
40 °C to 55 °C Itr ≤ I ≤ Imax 0,5 ind, 0,8 cap ± 7,2 ± 3,4 ± 2,4 Imin ≤ I ≤ Imax 1 ± 6,3 ± 3,1 ± 1,9 -40 °C to -25 °C
55 °C to 70 °C Itr ≤ I ≤ Imax 0,5 ind, 0,8 cap ± 9,4 ± 4,4 ± 3,1 Imin ≤ I ≤ Imax 1 ± 1,0 ± 0,7 ± 0,2 Voltage variation
± 10 % Itr ≤ I ≤ Imax 0,5 ind, 0,8 cap ± 1,5 ± 1,0 ± 0,4 Imin ≤ I ≤ Imax 1 ± 0,8 ± 0,5 ± 0,2 Frequency variation ± 2 % Itr ≤ I ≤ Imax 0,5 ind, 0,8 cap ± 1,0 ± 0,7 ± 0,2 NOTE For the relationships Imin / Itr and Imax / Itr see EN 50470-1, Table 3.
Table 7 – Limits of additional percentage error due to influence quantities (polyphase meters carrying a single phase load,
but with balanced polyphase voltages applied to voltage circuits) Limits of additional percentage error for meters of class index Influence quantity Value of current for direct connected or transformer operated meters Power factor A B C Temperature variation
1 ± 1,8 ± 0,9 ± 0,5 5 °C to 30 °C Itr ≤ I ≤ Imax 0,5 ind ± 2,7 ± 1,3 ± 0,9 1 ± 3,3 ± 1,6 ± 1,0 -10 °C to 5 °C
30 °C to 40 °C Itr ≤ I ≤ Imax 0,5 ind ± 4,9 ± 2,3 ± 1,6 1 ± 4,8 ± 2,4 ± 1,4 -25 °C to -10 °C
40 °C to 55 °C Itr ≤ I ≤ Imax 0,5 ind ± 7,2 ± 3,4 ± 2,4 1 ± 6,3 ± 3,1 ± 1,9 -40 °C to -25 °C
55 °C to 70 °C Itr ≤ I ≤ Imax 0,5 ind ± 9,4 ± 4,4 ± 3,1 1 ± 1,5 ± 1,0 ± 0,3 Voltage variation
± 10 % Itr ≤ I ≤ Imax 0,5 ind ± 2,0 ± 1,5 ± 0,5 1 ± 1,0 ± 0,7 ± 0,3 Frequency variation ± 2 % Itr ≤ I ≤ Imax 0,5 ind ± 1,3 ± 1,0 ± 0,3 NOTE For the relationship Imax / Itr see EN 50470-1, Table 3.
SIST EN 50470-3:2007



EN 50470-3:2006 – 10 – 8.4 Maximum permissible error (MPE) In addition to the requirements of 8.1 and 8.3, the composite error of the meter shall not exceed the values given in Table 8. When the operating range of the meter covers more than one temperature range, then the respective requirements for each temperature range apply. The composite error at a certain load shall be calculated from the following formula: )cos,,()cos,,()cos,,()cos,(2222ϕδϕδϕδϕIfIUITIeec+++= where )cos,(ϕIe = the intrinsic error of the meter at a certain load; )cos,,(ϕδIT = the additional percentage error due to the variation of the temperature at the same load; )cos,,(ϕδIU = the additional percentage error due to the variation of the voltage at the same load; )cos,,(ϕδIf= the additional percentage error due to the variation of the frequency at the same load. See also 8.7.6. Table 8 – Maximum permissible error (MPE) Operating temperature range 5 °C to 30 °C -10 °C to 5 °C or 30 °C to 40 °C -25 °C to -10 °C or
40 °C to 55 °C -40 °C to -25 °C or 55 °C to 70 °C Meter class index Value of current Power factor A B C A B C A B C A B C Single-phase meter; polyphase meter with balanced loads Imin ≤ I < Itr 1 ± 3,5 ± 2,0 ± 1,0 ± 5,0 ± 2,5 ± 1,3 ± 7,0 ± 3,5 ± 1,7 ± 9,0 ± 4,0 ± 2,0 Itr ≤ I ≤ Imax 0,5 ind…1…0,8 cap ± 3,5 ± 2,0 ± 0,7 ± 4,5 ± 2,5 ± 1,0 ± 7,0 ± 3,5 ± 1,3 ± 9,0 ± 4,0 ± 1,5 Polyphase meter carrying a single-phase load, but with balanced voltage supplied to the voltage circuits Itr ≤ I ≤ Imax 0,5 ind…1 ± 4,0 ± 2,5 ± 1,0 ± 5,0 ± 3,0 ± 1,3 ± 7,0 ± 4,0 ± 1,7 ± 9,0 ± 4,5 ± 2,0
8.5 Effect of disturbances of long duration When the meter is otherwise operated at reference conditions, the additional percentage error due to disturbances of long duration, when applied one by one, shall not exceed the critical change values specified in Table 9. For testing, see 8.7.7. SIST EN 50470-3:2007



– 11 – EN 50470-3:2006 Table 9 – Effect of disturbances of long duration – Critical change values Value of current (balanced unless otherwise stated) Critical change value for meters of class index, % Disturbance Value For direct connected meters For trans-former operated meters Power factor A B C 1 ± 3,0 ± 2,1 ± 0,6 0,8 Un ≤ U < 0,9 Un 1,1 Un < U ≤ 1,15 Un 0,5 ind ± 4,5
± 3,0 ± 1,2 Severe voltage variation U < 0,8 Un 10 Itr
In
1 and 0,5 ind +10…–100 Reversed phase sequence Any two phases interchanged Itr 0,1 In 1 ± 1,5 ± 1,5 ± 0,3 Voltage unbalance One or two phases interrupted a 10 Itr In 1 ± 4,0 ± 2,0 ± 1,0 1 ± 1,0 ± 0,7 ± 0,2 Self-heating
Imax Imax 0,5 ind ± 1,5 ± 1,0 ± 0,2 Earth fault b 1,9 Un on two lines - 0,5 In 1 ± 1,0 ± 0,7 ± 0,3 Harmonic components in the current and voltage circuits 10 % U,
40 % I 5th harmonic 0,5 Imax 0,5 Imax 1 ± 1,0 ± 0,8 ± 0,5 DC and even harmonics in the a.c. current circuit c
2maxI - 1 ± 6,0 ± 3,0 ± 1,5 Odd harmonics in the a.c. current circuit
5 Itr
0,5 In
1 ± 6,0 ± 3,0 ± 1,5 Sub-harmonics in the a.c. current circuit
5 Itr
0,5 In
1 ± 6,0 ± 3,0 ± 1,5 Continuous magnetic fields of external origin 1 000 Ampere-turns 10 Itr
In 1 ± 3,0 ± 2,0 ± 1,0 Power frequency magnetic fields of external origin 0,5 mT 10 Itr In 1 ± 3,0 ± 2,0 ± 1,0 Radiated RF electromagnetic fields 10 V/m 10 Itr In 1 ± 3,0 ± 2,0 ± 1,0 Operation of auxiliary devices Most unfavourable condition Imin Imin 1 ± 1,0 ± 0,5 ± 0,1 Electrical fast transient/burst 4 kV (2 kV) 10 Itr
In 1 ± 6,0 ± 4,0 ± 2,0 Conducted disturbances induced by RF fields 10 V 10 Itr In 1 ± 3,0 ± 2,0 ± 1,0 Damped oscillatory waves d 2,5 kV / 1 kV - In 1 ± 3,0 ± 2,0 ± 1,0 a Polyphase meters with three measuring elements shall measure and register, within the limits of variation in percentage error shown in this table, if the following phases are interrupted. – in a three-phase, four wire network one or two phases ; – in a three-phase, three-wire network (if the meter is designed for this service) one of the three phases. This only covers phase interruptions and does not cover events such as transformer fuse failures. In case of polyphase meters with two measuring elements the test does not apply. b Only for three-phase four-wire voltage transformer operated meters connected to distribution network equipped with earth fault neutralizers. c This requirement does not apply to current transformer operated meters. d For voltage transformer operated meters only. SIST EN 50470-3:2007



EN 50470-3:2006 – 12 – For testing, see 8.7.7. 8.6 Short time overcurrents Short-time overcurrents shall not damage the meter. The meter shall perform correctly when back to its initial working condition and the additional error shall not exceed the critical change value specified in Table 10. NOTE This requirement does not apply to meters having a contact in the current circuits. For this case, see the appropriate standards. Table 10 – Effect of short time overcurrents – Critical change value Critical change value for meters of class index, % Meters for Value of current (balanced) Power factor A B C Direct connection 10 Itr - 1 ± 1,5 ± 1,5
± 1,5
Connection through current transformer - In 1 ± 1,5 ± 1,5 ± 1,5
For testing, see 8.7.8. 8.7 Performing the tests 8.7.1 Accuracy test conditions To test the accuracy requirements, the following test conditions shall be maintained: a) the meter shall be tested in its case with the cover in position; all parts intended to be earthed shall be earthed; b) before any test is made, the circuits shall have been energized for a time su
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