SIST EN 62271-110:2009
(Main)High-voltage switchgear and controlgear - Part 110: Inductive load switching (IEC 62271-110:2009)
High-voltage switchgear and controlgear - Part 110: Inductive load switching (IEC 62271-110:2009)
This International Standard is applicable to a.c. circuit-breakers designed for indoor or outdoor installation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1000 V and applied for inductive current switching with or without additional short-circuit current breaking duties. The standard is applicable to circuit-breakers in accordance with IEC 62271-100 that are used to switch high-voltage motor currents and shunt reactor currents and also to high-voltage contactors used to switch high-voltage motor currents [2]. Switching unloaded transformers, i.e. breaking transformer magnetizing current, is not considered in this standard. The reasons for this are as follows: a) due to the non-linearity of the transformer core, it is not possible to correctly model the switching of transformer magnetizing current using linear components in a test laboratory. Tests conducted using an available transformer, such as a test transformer, will only be valid for the transformer tested and cannot be representative for other transformers; b) as detailed in CIGRE Technical Brochure 305 [1], the characteristics of this duty are usually less severe than any other inductive current switching duty. It should be noted that such a duty may produce severe overvoltages within the transformer winding(s) depending on the circuit-breaker re-ignition behaviour and transformer winding resonance frequencies. Short-line faults, out-of-phase current making and breaking and capacitive current switching are not applicable to circuit-breakers applied to switch shunt reactors or motors. These duties are therefore not included in this standard. Subclause 1.1 of IEC 62271-100 is otherwise applicable.
Hochspannungs-Schaltgeräte und -Schaltanlagen - Teil 110: Schalten induktiver Lasten (CEI 62271-110:2009)
Appareillage à haute tension - Partie 110: Manoeuvre de charges inductives (IEC 62271-110:2009)
La CEI 62271-110:2009 est applicable aux disjoncteurs à courant alternatif conçus pour une installation à l'intérieur ou à l'extérieur, et pour fonctionner à des fréquences de 50 Hz à 60 Hz, sur des réseaux de tensions supérieures à 1 000 V et prévus pour l'établissement et la coupure de courants inductifs avec ou sans pouvoir de coupure de court-circuit additionnel. Cette norme est applicable aux disjoncteurs selon CEI 62271-100 et qui sont utilisés pour l'établissement et la coupure de courants de moteurs à haute tension et de réactances shunt, et aussi aux contacteurs à haute tension utilisés pour l'établissement et la coupure de courants de moteurs à haute tension. Cette deuxième édition annule et remplace la première édition datée 2005, elle constitue en une révision rédactionnelle. Par rapport à la première édition toutes les références à la CEI 60694 ont été remplacées par la celles à la CEI 62271-1. Cette norme doit être lue en conjonction avec la CEI 62271-1, première édition, parue en 2007, et avec la CEI 62271-100, deuxième édition, parue en 2008. Cette publication doit être lue conjointement avec la CEI 62271-1:2007 et la CEI 62271-100:2008.
Visokonapetostne stikalne in krmilne naprave - 110. del: Preklapljanje induktivnega bremena (IEC 62271-110:2009)
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Visokonapetostne stikalne in krmilne naprave - 110. del: Preklapljanje induktivnega bremena (IEC 62271-110:2009)Hochspannungs-Schaltgeräte und -Schaltanlagen - Teil 110: Schalten induktiver Lasten (CEI 62271-110:2009)Appareillage à haute tension - Partie 110: Manoeuvre de charges inductives (IEC 62271-110:2009)High-voltage switchgear and controlgear - Part 110: Inductive load switching (IEC 62271-110:2009)29.130.10Visokonapetostne stikalne in krmilne napraveHigh voltage switchgear and controlgearICS:Ta slovenski standard je istoveten z:EN 62271-110:2009SIST EN 62271-110:2009en,fr01-julij-2009SIST EN 62271-110:2009SLOVENSKI
STANDARDSIST EN 62271-110:20061DGRPHãþD
SIST EN 62271-110:2009
EUROPEAN STANDARD EN 62271-110 NORME EUROPÉENNE
EUROPÄISCHE NORM May 2009
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: avenue Marnix 17, B - 1000 Brussels
© 2009 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62271-110:2009 E
ICS 29.130.10 Supersedes EN 62271-110:2005
English version
High-voltage switchgear and controlgear -
Part 110: Inductive load switching (IEC 62271-110:2009)
Appareillage à haute tension -
Partie 110: Manoeuvre
de charges inductives (CEI 62271-110:2009)
Hochspannungs-Schaltgeräte
und -Schaltanlagen -
Teil 110: Schalten induktiver Lasten (IEC 62271-110:2009)
This European Standard was approved by CENELEC on 2009-04-01. 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, Bulgaria, 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 62271-110:2009
EN 62271-110:2009
– 2 – Foreword The text of document 17A/843/FDIS, future edition 2 of IEC 62271-110, prepared by SC 17A,
High-voltage switchgear and controlgear, of IEC TC 17, Switchgear and controlgear, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62271-110 on 2009-04-01. This European Standard supersedes EN 62271-110:2005. The main changes from EN 62271-110:2005 are that all references to EN 60694 have been replaced with EN 62271-1. This standard is to be read in conjunction with EN 62271-1:2008 and with EN 62271-100:2009 to which it refers and which are applicable, unless otherwise specified. In order to simplify the indication of corresponding requirements, the same numbering of clauses and subclauses is used as in EN 62271-1 and EN 62271-100. Additional subclauses are numbered from 101. 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) 2010-01-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow) 2012-04-01 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 62271-110:2009 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following note has to be added for the standard indicated: IEC 60470 NOTE
Harmonized as EN 60470:2000 (not modified). __________ SIST EN 62271-110:2009
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Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
Addition to Annex ZA of EN 62271-100:
Publication Year Title EN/HD Year
IEC 62271-100 2008 High-voltage switchgear and controlgear - Part 100: Alternating current circuit-breakers EN 62271-100 2009
SIST EN 62271-110:2009
SIST EN 62271-110:2009
IEC 62271-110Edition 2.0 2009-01INTERNATIONAL STANDARD NORME INTERNATIONALEHigh-voltage switchgear and controlgear –
Part 110: Inductive load switching
Appareillage à haute tension –
Partie 110: Manœuvre de charges inductives
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE TICS 29.130.10 PRICE CODECODE PRIXISBN 2-8318-1021-2
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale SIST EN 62271-110:2009
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CONTENTS FOREWORD.4 1 General.6 1.1 Scope.6 1.2 Normative references.6 2 Normal and special service conditions.6 3 Definitions.6 4 Ratings.7 4.1 Rated voltage (Ur).7 4.2 Rated insulation level.7 4.3 Rated frequency (fr).7 4.4 Rated normal current (Ir) and temperature rise.7 4.5 Rated short-time withstand current (Ik).7 4.6 Rated peak withstand current (Ip).7 4.7 Rated duration of short-circuit (tk).7 4.8 Rated supply voltage of closing and opening devices and of auxiliary and control circuits (Ua).7 4.9 Rated supply frequency of closing and opening devices and auxiliary circuits.7 4.10 Rated pressure of compressed gas supply for insulation, operation and/or interruption.7 5 Design and construction.8 6 Type tests.8 6.1 General.8 6.2 Dielectric test.8 6.3 Radio interference voltage (r.i.v.) tests.9 6.4 Measurement of the resistance of the main circuit.9 6.5 Temperature-rise tests.9 6.6 Short-time withstand current and peak withstand current tests.9 6.7 Verification of protection.9 6.8 Tightness tests.9 6.9 Electromagnetic compatibility (EMC) tests.9 6.101 Mechanical and environmental tests.9 6.102 Miscellaneous provisions for making and breaking tests.9 6.103 Test circuits for short-circuit making and breaking tests.9 6.104 Short-circuit test quantities.9 6.105 Short-circuit test procedures.9 6.106 Basic short-circuit test duties.10 6.107 Critical current tests.10 6.108 Single-phase and double-earth fault tests.10 6.114 High-voltage motor current switching tests.10 6.115 Shunt reactor current switching tests.14 7 Routine tests.19 8 Guide to selection of circuit-breakers for service.19 9 Information to be given with enquiries, tenders and orders.19 10 Rules for transport, storage, installation, operation and maintenance.20 11 Safety.20 SIST EN 62271-110:2009
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Bibliography.24
Figure 1 – Motor switching test circuit and summary of parameters.20 Figure 2 – Illustration of transient voltages at interruption of inductive current for first phase clearing in a three-phase non-solidly earthed circuit.21 Figure 3 – Reactor switching test − Basic layout of three-phase test circuit.22 Figure 4 – Reactor switching test − Basic layout of single-phase test circuit.22 Figure 5 – Illustration of transient voltages at interruption of inductive current for a single-phase test.23
Table 1 – Test duties at motor current switching tests.13 Table 2 – Prospective transient voltage of load circuit including connection to the circuit-breaker.16 Table 3 – Load circuit 1 test currents.17 Table 4 – Load circuit 2 test currents.17 Table 5 – Test duties for reactor current switching tests.18
SIST EN 62271-110:2009
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INTERNATIONAL ELECTROTECHNICAL COMMISSION _____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 110: Inductive load switching
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees. 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 62271-110 has been prepared by subcommittee 17A: High-voltage switchgear and controlgear, of IEC technical committee 17: Switchgear and controlgear. This second edition cancels and replaces the first edition dated 2005 and constitutes an editorial revision. The main changes from the first edition are that all references to IEC 60694 have been replaced with IEC 62271-1.
SIST EN 62271-110:2009
62271-110 © IEC:2009 – 5 –
The text of this standard is based on the following documents: FDIS Report on voting 17A/843/FDIS 17A/856/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. This standard is to be read in conjunction with IEC 62271-1, first edition, published in 2007, and with IEC 62271-100, second edition, published in 2008, to which it refers and which are applicable, unless otherwise specified. In order to simplify the indication of corresponding requirements, the same numbering of clauses and subclauses is used as in IEC 62271-1 and IEC 62271-100. Additional subclauses are numbered from 101. A list of all the parts in the IEC 62271 series, under the general title High-voltage switchgear and controlgear, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date
indicated on the IEC web site under “http://webstore.iec.ch” in the data related to the specific publication. At this date, the publication will be
• reconfirmed; • withdrawn; • replaced by a revised edition, or • amended. SIST EN 62271-110:2009
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HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 110: Inductive load switching
1 General 1.1 Scope This International Standard is applicable to a.c. circuit-breakers designed for indoor or outdoor installation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1000 V and applied for inductive current switching with or without additional short-circuit current breaking duties. The standard is applicable to circuit-breakers in accordance with IEC 62271-100 that are used to switch high-voltage motor currents and shunt reactor currents and also to high-voltage contactors used to switch high-voltage motor currents [2]. Switching unloaded transformers, i.e. breaking transformer magnetizing current, is not considered in this standard. The reasons for this are as follows: a) due to the non-linearity of the transformer core, it is not possible to correctly model the switching of transformer magnetizing current using linear components in a test laboratory. Tests conducted using an available transformer, such as a test transformer, will only be valid for the transformer tested and cannot be representative for other transformers; b) as detailed in CIGRE Technical Brochure 305 [1], the characteristics of this duty are usually less severe than any other inductive current switching duty. It should be noted that such a duty may produce severe overvoltages within the transformer winding(s) depending on the circuit-breaker re-ignition behaviour and transformer winding resonance frequencies. Short-line faults, out-of-phase current making and breaking and capacitive current switching are not applicable to circuit-breakers applied to switch shunt reactors or motors. These duties are therefore not included in this standard. Subclause 1.1 of IEC 62271-100 is otherwise applicable. 1.2 Normative references Subclause 1.2 of IEC 62271-100 is applicable with the following addition: IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: High-voltage alternating-current circuit-breakers
2 Normal and special service conditions Clause 2 of IEC 62271-1 is applicable. 3 Definitions For the purposes of this document, the definitions of IEC 60050(441) and IEC 62271-1 apply. SIST EN 62271-110:2009
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4 Ratings Clause 4 of IEC 62271-100 is applicable except for the references to short-line faults, out-of-phase making and breaking, capacitive current switching and as noted in specific subclauses below. 4.1 Rated voltage (Ur) Subclause 4.1 of IEC 62271-1 is applicable. 4.2 Rated insulation level Subclause 4.2 of IEC 62271-1 is applicable with the following addition: The rated values stated in Tables 1a and 1b and Tables 2a and 2b of IEC 62271-1 are applicable with the exception of column (8) in the latter two tables. NOTE 1 The reason for this exception is the passive nature of the shunt reactor load circuit. NOTE 2 In some cases (high chopping overvoltage levels, or where a neutral reactor is present or in cases of shunt reactors with isolated neutral), it may be necessary to specify an appropriate insulation level which is higher than the rated values given in Tables 1a, 1b, 2a and 2b. 4.3 Rated frequency (fr) Subclause 4.3 of IEC 62271-1 is applicable with the following addition: The standard values for the rated frequency of high voltage circuit-breakers are 50 Hz and 60 Hz. 4.4 Rated normal current (Ir) and temperature rise Subclause 4.4 of IEC 62271-1 is applicable. 4.5 Rated short-time withstand current (Ik) Subclause 4.5 of IEC 62271-100 is applicable. 4.6 Rated peak withstand current (Ip) Subclause 4.6 of IEC 62271-100 is applicable. 4.7 Rated duration of short-circuit (tk) Subclause 4.7 of IEC 62271-100 is applicable. 4.8 Rated supply voltage of closing and opening devices and of auxiliary and control circuits (Ua) Subclause 4.8 of IEC 62271-1 is applicable. 4.9 Rated supply frequency of closing and opening devices and auxiliary circuits Subclause 4.9 of IEC 62271-1 is applicable. 4.10 Rated pressure of compressed gas supply for insulation, operation and/or interruption Subclause 4.10 of IEC 62271-1 is applicable. SIST EN 62271-110:2009
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4.101 Rated short-circuit breaking current (Isc) Subclause 4.101 of IEC 62271-100 is applicable. 4.102 Transient recovery voltage related to the rated short-circuit breaking current Subclause 4.102 of IEC 62271-100 is applicable. 4.103 Rated short-circuit making current Subclause 4.103 of IEC 62271-100 is applicable. 4.104 Rated operating sequence Subclause 4.104 of IEC 62271-100 is applicable. 4.108 Inductive load switching This standard is applicable. 4.109 Rated time quantities Subclause 4.109 of IEC 62271-100 is applicable. 4.110 Number of mechanical operations Subclause 4.110 of IEC 62271-100 is applicable. 5 Design and construction Clause 5 of IEC 62271-100 is applicable. 6 Type tests 6.1 General Subclause 6.1 of IEC 62271-100 is applicable with the following addition: Inductive current switching tests performed for a given current rating and type of application may be considered valid for another current rating and same type of application as detailed below: a) for high-voltage shunt reactor switching at rated voltage 52 kV and above, tests at a particular current rating are to be considered valid for applications up to the tested current value +20 %; b) for shunt reactor switching at rated voltage below 52 kV, no type testing is required and reference should be made to the guide [1]; c) for high-voltage motor switching, no further type testing is considered necessary for stalled motor currents between 100 A and 300 A or for stalled motor currents between 300 A and the current associated with the short-circuit current of test duty T10 according to 6.106.1 of IEC 62271-100. 6.2 Dielectric test Subclause 6.2 of IEC 62271-100 is applicable with the following addition: SIST EN 62271-110:2009
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Refer to 4.2 of this standard. 6.3 Radio interference voltage (r.i.v.) tests Subclause 6.3 of IEC 62271-1 is applicable. 6.4 Measurement of the resistance of the main circuit Subclause 6.4 of IEC 62271-1 is applicable. 6.5 Temperature-rise tests Subclause 6.5 of IEC 62271-1 is applicable. 6.6 Short-time withstand current and peak withstand current tests Subclause 6.6 of IEC 62271-1 is applicable. 6.7 Verification of protection Subclause 6.7 of IEC 62271-1 is applicable. 6.8 Tightness tests Subclause 6.8 of IEC 62271-1 is applicable. 6.9 Electromagnetic compatibility (EMC) tests Subclause 6.9 of IEC 62271-1 is applicable. 6.101 Mechanical and environmental tests Subclause 6.101 of IEC 62271-100 is applicable. 6.102 Miscellaneous provisions for making and breaking tests Subclause 6.102 of IEC 62271-100 is applicable with the following addition: High-voltage motor current and shunt reactor switching tests shall be performed at rated auxiliary and control voltage or, where necessary, at maximum auxiliary and control voltage to facilitate consistent control of the opening and closing operation according to 6.102.3.1 of IEC 62271-100 and at rated functional pressure for interruption and insulation. For gas circuit-breakers shunt reactor switching tests shall also be performed at the minimum functional pressure for interruption and insulation. 6.103 Test circuits for short-circuit making and breaking tests Subclause 6.103 of IEC 62271-100 is applicable. 6.104 Short-circuit test quantities Subclause 6.104 of IEC 62271-100 is applicable. 6.105 Short-circuit test procedures Subclause 6.105 of IEC 62271-100 is applicable. SIST EN 62271-110:2009
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6.106 Basic short-circuit test duties Subclause 6.106 of IEC 62271-100 is applicable. 6.107 Critical current tests Subclause 6.107 of IEC 62271-100 is applicable. 6.108 Single-phase and double-earth fault tests Subclause 6.108 of IEC 62271-100 is applicable. NOTE Subclauses 6.109 to 6.112 of IEC 62271-100 are not applicable to this standard. 6.114 High-voltage motor current switching tests 6.114.1 Applicability This subclause is applicable to three-phase alternating current circuit-breakers having rated voltages above 1 kV and up to 17,5 kV, which are used for switching high-voltage motors. Tests may be carried out at 50 Hz with a relative tolerance of ±10 % or 60 Hz with a relative tolerance of ±10 %, both frequencies being considered equivalent. Motor switching tests are applicable to all three-pole circuit-breakers having rated voltages equal to or less than 17,5 kV, which may be used for the switching of three-phase asynchronous squirrel-cage or slip-ring motors. The circuit-breaker may be of a higher rated voltage than the motor when connected to the motor through a stepdown transformer. However, the more usual application is a direct cable connection between circuit-breaker and motor. When tests are required, they shall be made in accordance with 6.114.2 to 6.114.9. No limits to the overvoltages are given as the overvoltages are only relevant to the specific application. Overvoltages between phases may be as significant as phase-to-earth overvoltages. 6.114.2 General The switching tests can be either field tests or laboratory tests. As regards overvoltages, the switching of the current of a starting or stalled motor is usually the more severe operation. Due to the non-linear behaviour of the motor iron core, it is not possible to exactly model the switching of motor current using linear components in a test station. Tests using linear components to simulate the motors can be considered to be more conservative than switching actual motors. For laboratory tests a standardized circuit simulating the stalled condition of a motor is specified (refer to Figure 1). The parameters of this test circuit have been chosen to represent a relatively severe case with respect to overvoltages and will cover the majority of service applications. The laboratory tests are performed to prove the ability of a circuit-breaker to switch motors and to establish its behaviour with respect to switching overvoltages, re-ignitions and current chopping. These characteristics may serve as a basis for estimates of the circuit-breaker performance in other motor circuits. Tests performed with the test currents defined in 6.114.3 and 6.114.4 demonstrate the capability of the switching device to switch high-voltage motors up to its rated interrupting current. For field tests, actual circuits are used with a supply system on the source side and a cable and motor on the load side. There may be a transformer between the circuit-breaker and SIST EN 62271-110:2009
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motor. However, the results of such field tests are only valid for circuit-breakers working in circuits similar to those during the tests. The apparatus under test includes the circuit-breaker with overvoltage protection devices if they are normally fitted. NOTE 1 Overvoltages may be produced when switching running motors. This condition is not represented by the substitute circuit, but is regarded as less severe. NOTE 2 The starting period switching of a slip-ring motor is generally less severe due to the effect of the starting resistor. NOTE 3 The rated voltage of the circuit-breaker may differ from that of the motor. 6.114.3 Characteristics of the supply circuits 6.114.3.1 General A three-phase supply circuit shall be used. The tests shall be performed using two different supply circuits A and B as specified in 6.114.3.2 and 6.114.3.3, respectively. Supply circuit A represents the case of a motor connected directly to a transformer. Supply circuit B represents the case where parallel cables are applied on the supply side. 6.114.3.2 Supply circuit A The three-phase supply may be earthed through a high ohmic impedance so that the supply voltage is defined with respect to earth. The impedance value shall be high enough to limit a prospective line-to-earth fault current to a value below the test current.
The source inductance Ls shall not be lower than that corresponding to the rated short-circuit breaking current of the tested circuit-breaker. Its impedance shall also be not higher than 0,1 times the impedance of the inductance in the load circuit (see 6.114.4). The supply side capacitance Cs is represented by three capacitors connected in earthed star. Their value, including the natural capacitance of the circuit shall be 0,04 µF ± 0,01 µF. The inductance Lb1 of the capacitors and connections shall not exceed 2 µH. The busbar inductance is represented by three bars forming a busbar each 6 m ± 1 m in length and spaced at a distance appropriate to the rated voltage. 6.114.3.3 Supply circuit B As supply circuit A with the value of the supply side capacitance increased to 1,75 µF ± 0,25 µF. 6.114.4 Characteristics of the load circuit 6.114.4.1 General A three-phase load circuit shall be used. The motor substitute circuit is connected to the circui
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