IEEE C37 013a-2007

IEEE Std C37.013a™-2007(Amendment to

IEEE Std C37.013-1997)

IEEE Standard for AC High VoltageGenerator Circuit Breakers Rated ona Symmetrical Current Basis

Amendment 1: Supplement for Use with Generators Rated 10–100 MVA

I E E E3 Park Avenue New York, NY 10016-5997, USA

6 June 2007

IEEE Power Engineering SocietySponsored by theSwitchgear Committee

Authorized licensed use limited to: UNIVERSIDADE FEDERAL DE SANTA CATARINA. Downloaded on April 22,2010 at 16:59:43 UTC from IEEE Xplore. Restrictions apply.


IEEE Std C37.013a™-2007

IEEE Standard for AC High Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis


Sponsor

Switchgear Committee of the IEEE Power Engineering Society

Approved 8 March 2007

IEEE-SA Standards Board


The Working Group thanks the International Electrotechnical Commission (IEC) for permission to reproduce information from its International Standard IEC 60694 (2002) and IEC 602271-100 (2006). All such extracts are copyright of IEC, Geneva, Switzerland. All rights reserved. Further information on the IEC is available from www.iec.ch. IEC has no responsibility for the placement and context in which the extracts and contents are reproduced by the author, nor is IEC in any way responsible for the other content or accuracy therein. Abstract: This amendment includes special requirements better suited for generator circuit breakers used to protect smaller generators rated between 10 MVA and 50 MVA and between 50 MVA and 100 MVA. It is important because the existing standards for typical distribution circuit breakers specifically exclude generator circuit breakers from the scope.

Keywords: circuit breaker, generator, generator circuit breaker, high voltage, transformer _________________________ The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright © 2007 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 6 June 2007. Printed in the United States of America. IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics Engineers, Incorporated. Print: ISBN 0-7381-5525-X SH95628 PDF: ISBN 0-7381-5526-8 SS95628 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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iv Copyright © 2007 IEEE. All rights reserved.

Introduction

The 1997 edition of IEEE Std C37.013, although approved as an IEEE Standard, failed to win approval as an ANSI standard because, although the Scope says that it covers “…all ac high-voltage generator circuit breakers…,” the requirements for small generator circuit breakers were not adequately addressed. It is the main purpose of this supplement to add specific requirements for smaller generator circuit applications, and focusing in particular on circuit breakers for use with generators rated in the 10 MVA to 100 MVA range. The supplement includes additional preferred ratings as well as other requirements that supplement the main requirements of 1997 edition. One important addition can be found in Annex B, which gives guidance regarding the effects of cable connections on the transient recovery voltage requirements for generator circuits. It would be well to mention two items, which were proposed for change, but in the end were not incorporated:

a) It was proposed that in 5.5 of IEEE Std C37.013-1997, an alternative rated short-circuit duty cycle, CO – 30 s – CO, should be added to the existing preferred duty cycle of CO – 30 min – CO. After much discussion, it was decided that, even if circuit breakers were available with the faster 30 s reclosing time, most likely it would never be needed. If there were a fault on either the transformer-side or the generator-side of the circuit breaker, it would be highly unlikely that such a fault could clear itself, so that an attempted reclosing operation would probably be unsuccessful anyway. Furthermore, it would take at least 30 minutes for someone to go to check the circuit to verify whether it should be reclosed. Therefore, the “CO – 30 min – CO” remains the preferred duty cycle.

b) It was proposed that, in Figure 15 of IEEE Std C37.013-1997, the parameters u’ and t’ should be defined for the coordinates of the upper end point on the “delay line” and that preferred values should be established for those parameters. After much discussion, it was concluded that, as the transient recovery voltage wave will have begun to bend away from the upper end of the delay line, the actual end point is not critical, and therefore, it is not specified.

Notice to users

Errata

Errata, if any, for this and all other standards can be accessed at the following URL: http:// standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for errata periodically.

Interpretations

Current interpretations can be accessed at the following URL: http://standards.ieee.org/reading/ieee/interp/ index.html.

This introduction is not part of IEEE Std C37.013a-2007, IEEE Standard for AC High Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis—Amendment 1: Supplement for use with Generators Rated 10–100 MVA.


v Copyright © 2007 IEEE. All rights reserved.

Patents

Attention is called to the possibility that implementation of this amendment may require use of subject matter covered by patent rights. By publication of this amendment, no position is taken with respect to the existence or validity of any patent rights in connection therewith. The IEEE shall not be responsible for identifying patents or patent applications for which a license may be required to implement an IEEE standard or for conducting inquiries into the legal validity or scope of those patents that are brought to its attention.

Participants

At the time this amendment was completed, the Small Generator Circuit Breaker Supplement Working Group had the following membership:

R. William Long, Chair

Anne Bosma Dieter Braun Denis Dufournet

Georges Montillet Neal McCord Nigel P. McQuin Martin Motz

Erich Ruoss H. Melvin Smith Gerald J. Watson

The following members of the individual balloting committee voted on this amendment. Balloters may have voted for approval, disapproval, or abstention. Roy Alexander W. J. (Bill) Bergman Stan Billings Anne Bosma Dieter Braun Lyne Brisson Ted Burse Tommy Cooper Ronald Daubert Dufournet Denis Alexander Dixon Doug Edwards Gary Engmann Marcel Fortin William G. Fossey Ruben Garzon Douglas Giraud Keith Gray Randall Groves

Erik Guillot Harold L. Hess Edward Horgan Jr. David Jackson Richard Jackson Jerry Jerabek Stephen R. Lambert John Leach Jason Lin Albert Livshitz Franco Lo Monaco R. William Long Gregory Luri William Majeski Neil McCord Nigel P. McQuin Gary Michel Daleep Mohla Georges Montillet

Arun Narang Jeffrey Nelson Paul Notarian T. W. Olsen Miklos Orosz David Peelo Ralph Philbrook III James Ruggieri Devki Sharma Jordan Shikoski H. Melvin Smith R. Kirkland Smith Allan St. Peter Stanton Telander Shanmugan Thamilarasan Gerald Vaughn Charles Wagner James Wilson Zhenxue Xu


vi Copyright © 2007 IEEE. All rights reserved.

When the IEEE-SA Standards Board approved this amendment on 8 March 2007, it had the following membership:

Steve M. Mills, Chair Richard H. Hulett, Vice Chair

Don Wright, Past Chair Judith Gorman, Secretary

Richard DeBlasio Alex Gelman William R. Goldbach Arnold M. Greenspan Robert M. Grow Joanna N. Guenin Julian Forster* Kenneth S. Hanus William B. Hopf

Herman Koch Joseph L. Koepfinger* John Kulick David J. Law Glenn Parsons Ronald C. Petersen Tom A. Prevost Narayanan Ramachandran Greg Ratta

Robby Robson Anne-Marie Sahazizian Virginia C. Sulzberger Malcolm V. Thaden Richard L. Townsend Walter Weigel Howard L. Wolfman

*Member Emeritus Also included are the following nonvoting IEEE-SA Standards Board liaisons:

Satish K. Aggarwal, NRC Representative Richard DeBlasio, DOE Representative Alan H. Cookson, NIST Representative

Don Messina

IEEE Standards Program Manager, Document Development

Matthew J. Ceglia IEEE Standards Program Manager, Technical Program Development


vi Copyright © 2007 IEEE. All rights reserved.

Contents

1. Scope .......................................................................................................................................................... 1

2. References .................................................................................................................................................. 2

5. Ratings and required capabilities................................................................................................................ 2

5.3 Rated continuous current ..................................................................................................................... 2 5.8 Short-circuit current rating .................................................................................................................. 3 5.10 Rated load current switching capability............................................................................................. 7 5.12 Out-of-phase current switching ability .............................................................................................. 9

6. Tests ......................................................................................................................................................... 10

7. Application guide ..................................................................................................................................... 12

8. Bibliography............................................................................................................................................. 12

Annex B (informative) For generator circuit breakers connected to the step-up transformer by shielded cables—an example of the effects of added capacitance on TRV requirements for a system-source fault............................................................................................................................................................... 13



1 Copyright © 2007 IEEE. All rights reserved.

IEEE Standard for AC High Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis


NOTE—The editing instructions contained in this amendment define how to merge the material contained herein into the existing base standard and its amendments to form the comprehensive standard.

The editing instructions are shown in bold italic. Four editing instructions are used: change, delete, insert, and replace. Change is used to make corrections in existing text or tables. The editing instruction specifies the location of the change and describes what is being changed by using strikethrough (to remove old material) and underscore (to add new material). Delete removes existing material. Insert adds new material without disturbing the existing material. Insertions may require renumbering. If so, renumbering instructions are given in the editing instruction. Replace is used to make changes in figures or equations by removing the existing figure or equation and replacing it with a new one. Editorial notes will not be carried over into future editions because the changes will be incorporated into the base standard.

1. Scope

Change the existing paragraph as shown: This standard applies to all ac high-voltage generator circuit breakers rated on a symmetrical current basis that are installed between the generator and the transformer terminals. Requirements relative to ac high-voltage generator circuit breakers intended for use with generators and transformers rated 10 MVA or more are covered specifically. Generator circuits rated less than 10 MVA and pumped storage installations are considered a special applications, and their requirements are not completely covered by this standard.


IEEE Std C37.013a-2007 IEEE Standard for AC High Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis—Amendment 1:

Supplement for use with Generators Rated 10–100 MVA


2. References

Change the following references in Clause 2 as shown: ANSI C37.06-1987 2000(R1994), Switchgear: AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis—Preferred Ratings and Related Required Capabilities.1 IEC 60694: 1996Edition 2.2 (2002-01), Common specifications for high voltage switchgear and controlgear standards.2 IEEE Std C37.04TM-19941999, IEEE Standard Rating Structure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis (ANSI).3, 4 NEMA SG 4-19902000, Alternating Current High-Voltage Circuit Breaker.5 Insert the following references into Clause 2 in alphanumeric order, and keep the existing reference to the prior edition of IEEE Std C37.09TM-1979 that covers two-part testing: IEC 62271-100 Edition 1.1 (2003-05), High-voltage switchgear and controlgear—Part 100: High-voltage alternating-current circuit-breakers. IEEE Std C37.09TM-1999, IEEE Standard Test Procedure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis. IEEE Std C37.11TM-1997 (Reaff 2003), IEEE Standard Requirements for Electrical Control for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis or a Total Current Basis.

5. Ratings and required capabilities

5.3 Rated continuous current

Change the following paragraph as shown: The rated continuous current of a generator circuit breaker is the designated upper limit of current in rms amperes at power frequency, which it shall be required to carry continuously without exceeding any of the limitations designated in 5.3.1 and 5.3.2. Typical values include 1.2 kA, 1.6 kA, 2 kA, 2.5 kA, 3.15 kA, 4 kA, 5 kA, 6.3 kA, 8 kA, 10 kA, 12 kA, 16 kA, 20 kA, etc and so on.

1 ANSI publications are available from the Sales Department, American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, NY 10036, USA (http://www.ansi.org/). 2 IEC publications are available from the Sales Department of the International Electrotechnical Commission, Case Postale 131, 3, rue de Varembé, CH-1211, Genève 20, Switzerland/Suisse (http://www.iec.ch/). IEC publications are also available in the United States from the Sales Department, American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, NY 10036, USA (http://www.ansi.org/). 3 IEEE publications are available from the Institute of Electrical and Electronics Engineers, Inc., 445 Hoes Lane, Piscataway, NJ 08854, USA (http://standards.ieee.org/). 4 The IEEE standards or products referred to in this clause are trademarks of the Institute of Electrical and Electronics Engineers, Inc. 5 NEMA publications are available from Global Engineering Documents, 15 Inverness Way East, Englewood, CO 80112, USA (http://global.ihs.com/).





5.4.1 Dielectric strength of external insulation

Replace Table 4 with the following:

Table 4—Schedule of dielectric strength values for ac generator circuit breakers and external insulation

(Ref. IEC)a (Ref. ANSI) Insulation withstand voltagesb

Rated voltage

(kV, rms) Rated maximum

voltage (kV, rms)

Power frequency (kV, rms)

Lightning impulse 1.2 × 50 µs wave

(kV, peak)

Line Column 1 Column 2 Column 3 Column 4

1 7.2 5 20 60

2 12 8.25 28 75

3 17.5 8.25 / 15 38 95

4 — 15.5 50 110

5 24 27 60 125

6 36 38 80 150c a Reprinted from 4.1.1 and Table 1a of IEC 60694 Ed. 2.2 “Copyright © 2002 IEC, Geneva, Switzerland. www.iec.ch.” b For rated voltages between those listed in Column 1 or in Column 2, the higher values of insulation withstand voltage should be chosen from the higher line number in the table. c In Line 6 of Table 4, the Lightning Impulse Withstand Voltage value is not 170 kV, as no generators are rated 36 kV with a rated Lightning Impulse Withstand Voltage of 170 kV.

5.8 Short-circuit current rating

Insert the following text at the end of the existing paragraph: The short-circuit current rating of a generator circuit breaker is the rms symmetrical component of short-circuit current to which all required short-circuit capabilities are related. Procedures for determining the symmetrical short-circuit current duties that compare with ratings and related required capabilities are found in Clause 7. It is to be noted that, if the performance capability of a generator circuit breaker design has been demonstrated for a certain generator rating or transformer rating, then that performance capability is automatically demonstrated for a generator or a transformer of lower rating.

5.8.1 Rated short-circuit current

Change the existing paragraph as shown: The rated short-circuit current of a generator circuit breaker is the highest rms value of the symmetrical component of the three-phase short-circuit current. It is measured from the envelope of the current wave at the instant of primary arcing contact separation, and is the current that the generator circuit breaker shall be required to interrupt at the rated maximum voltage and rated duty cycle when the source of the short-circuit current is from the power system through at least one transformation. It establishes also, by ratios defined in 5.8.2.6, the highest current that the generator circuit breaker shall be required to close and latch against





and to carry. Typical values are 20 kA, 25 kA, 31.5 kA, 40 kA, 50 kA, 63 kA, 80 kA, 100 kA, 120 kA, 160 kA, etcand so on.

NOTE—The rare cases when the generator-source short-circuit current is higher than the system source short- circuit current need special consideration.6

5.8.2.7 Required short-time current-carrying capability

Change the first two paragraphs as shown: The generator circuit breaker shall be capable of carrying for a time Ts equal to 1 s, any short-circuit current, whose crest peak value does not exceed 2.74 times the rated short-circuit current, as determined from the envelope of the current wave, at the time of the maximum peak, and whose rms value I determined over the complete 1 s period, does not exceed the rated short-circuit current considered above. The mathematical expression for the rms value I of a short-circuit current over the period Ts is given in 7.1.6 of IEEE Std C37.09-1999 as follows:

∫∫ =⎟⎟⎟

⎠

⎞

⎜⎜⎜

⎝

⎛=

1

0

2

0

21 dtidtiTs

ITs

where i is the instantaneous current in amperes (see Clause 7 of IEEE Std C37.09-1979) t is the time from the initiation of the fault, in seconds

It is not to be inferred that the generator circuit breaker is to be capable of interrupting after the required short-time current-carrying capability duty until it has cooled down to normal heat run temperature.”

5.9.1 Rated inherent TRV

Change the first paragraph as shown: The rated inherent TRV is the reference voltage that constitutes the limit of the inherent transient recovery voltage of circuits that the circuit breaker shall be capable of withstanding under fault conditions and shall be defined by an oscillatory wave-shape having a TRV rate, time delay, and crest peak voltage (E2). Preferred values for rated TRV parameters are as listed in TRV Tables 5, and Table 6, Table 8, and Table 9. The formula and method for determining the time-to-crestpeak (T2) are given in 7.3.6.3 and Figure 15. Tables 5 and Table 6 provide the values of the inherent TRV parameters. If the circuit breaker requires that the inherent TRV be modified by the addition of capacitors, then the amount of equivalent capacitance required shall be given in the test report and on the nameplate. It is recognized that connecting a cable between the generator and the circuit breaker may provide this capacitance.7 Please refer to paragraph 6.2.3.7.3 for additional information.

6 Notes in text, tables, and figures are given for information only and do not contain requirements needed to implement the standard. 7 Inserted text has been taken from 4.102.1 of IEC 62271-100 “Copyright © 2006 IEC, Geneva, Switzerland. www.iec.ch.”






Table 5—TRV parameters for system-source faults

Inherent TRV

Transformer rating

(MVA) T2 —Time-to-peak (µs)

E2 —Peak voltage (kV)

TRV rate (kV/µs)


1 10–50 0.68 V 1.84 V 3.2

2 51–100 0.62 V 1.84 V 3.5

3 101–200 0.54 V 1.84 V 4.0

4 201–400 0.48 V 1.84 V 4.5

5 401–600 0.43 V 1.84 V 5.0

6 601–1000 0.39 V 1.84 V 5.5

7 1001 or more 0.36 V 1.84 V 6.0

NOTES:

1—Time delay shall be equal to or less than 1 μs.

2—V is the rated maximum voltage in kilovolts.


Table 6 —TRV parameters for generator-source faults

Inherent TRV

Generator rating



TRV rate (kV/µs)


1 10–50 1.44 V 1.84 V 1.5

2 51–100 1.35 V 1.84 V 1.6

3 101–400 1.20 V 1.84 V 1.8

4 401–800 1.08 V 1.84 V 2.0

5 801 or more 0.98 V 1.84 V 2.2

NOTES:

1—Time delay shall be equal to or less than 0.5 μs.






Insert the following subclauses after Table 6: 8

5.9.1.1 Representation of TRV waves

The waveform of transient recovery voltages in systems with a voltage less than 100 kV approximates to a damped single frequency oscillation. Two lines adequately represent this rising part of the TRV waveform. One line goes through the origin and tangent to the TRV curve with a slope equal to the TRV rate. The other line has the same slope and goes through the point td time delay. Methods of drawing TRV envelopes are given in 7.3.6.3. The influence of local capacitance on the source side of the circuit breaker produces a slower rate of rise of the voltage during the first few microseconds of the TRV. This is taken into account by introducing a time delay. It is understood that every part of the TRV wave can influence the interrupting capability of a circuit breaker.

5.9.1.2 Representation of TRV

The following parameters are used for the representation of TRV. The rising part of the TRV curve is bounded by two lines:

a) Reference line: The reference line goes through the origin and is tangent to the TRV curve with a slope equal to the TRV rate and represents the upper bound of the TRV envelope. (See Figure 15.)

T2 is the time to reach the peak voltage E2 in microseconds. E2 is the maximum reference voltage (TRV peak value), in kilovolts. t3 is the intersection point of the tangent to the recovery voltage and to the horizontal

line E2 representing the maximum recovery voltage, in microseconds.

NOTE—t3 is approximately equal to 0.88 × T2. The TRV parameters are defined as a function of the rated voltage (V), the first-pole-to-clear factor, the amplitude factor, and the above parameters. (See 7.3.6.3.)

b) Delay line of TRV: The delay line starts on the time axis at the rated time delay (td) and runs parallel to the first reference line (TRV line) and represents the lower bound of the TRV envelope. (See Figure 15.)

td is the time delay, in microseconds. The tolerance of the time delay is ±20%. For three-phase circuits, the inherent TRV refers to the first-pole-to-clear, i.e., the voltage across one open pole with the other two poles still conducting. The inherent TRV parameters for the test are defined as a function of the rated voltage (V) and are represented by the envelope drawn from the reference line and the delay line, as described in 7.3.6.3 and as shown in Figure 15. The inherent TRV of the test circuit shall be determined by such a method as will produce and measure the TRV wave without significantly influencing it. It shall be measured at the terminals to which the circuit breaker will be connected with all necessary test-measuring devices, such as voltage dividers. In circuits where such a measurement is not possible, for instance in certain synthetic test circuits, a calculation of the

8 Text from 5.9.1.1 and 5.9.1.2 has been taken from 4.102.2 of IEC 62271-100 “Copyright © 2006 IEC, Geneva, Switzerland. www.iec.ch.”





inherent TRV is allowed. (For an example, see the additional guidance as given in Annex F of IEC 62271-100, Ed. 1.) The transient recovery voltage during the test shall be recorded. During a short-circuit test, the circuit-breaker characteristics such as arc voltage, post-arc conductivity, and presence of switching resistors (if any) will affect the transient recovery voltage. Thus, the test transient recovery voltage will differ from the inherent TRV wave of the test circuit upon which the performance requirements are based to a degree depending on the characteristics of the circuit breaker. Unless the modifying effect of the circuit breaker is not significant and the breaking current does not contain a significant dc component, records taken during tests should not be used for assessing the inherent transient recovery voltage characteristics of the circuit; rather, this should be done by other means. (Additional guidance is given in Annex F of IEC 62271-100, Ed. 1.) Please refer to 6.2.3.7.3 for additional information

5.10 Rated load current switching capability

Insert the following new subclause and renumber subsequent subclauses:

5.10.1 Operation endurance capability classes M1 and M2

The operation endurance capabilities specified in Table 7 indicate the type and number of complete closing–opening operations that the generator circuit breaker shall be capable of performing for the operation endurance classes M1 or M2, under the following conditions:

a) The generator circuit breaker shall operate with rated control voltage and rated fluid (gas or liquid) pressure in the operating mechanism.

b) The frequency of operations is not to exceed two in 30 min and four in 4 h because the generator circuit breaker may be equipped with auxiliary devices, such as resistors, that have thermal limitations. When auxiliary devices such as resistors are not used, the manufacturer may provide an alternative frequency of operation values.

c) The values listed in the rating tables have been established by experience and engineering judgment. Those involving currents are derived from service capability and circuit breaker condition (see 5.8.3.2) and are not separate ratings (see 6.2.8.2).





Replace Table 7 with the following: Table 7—Schedule of operation endurance capabilities for ac generator circuit breakers

with operation endurance class M1 and class M2 Number of operations ( 1 operation means 1 closing and 1 opening)

Generator circuit breaker endurance classa

Between servicingb

No-load Mechanicalb–h

Continuous current switchingb,d,e,g,h,i

Line Column 1 Column 2 Column 3 Column 4 1 M1 500 1000 50 2 M2 1000 3000 150 a The integrated duty on the generator circuit breaker must be within the service capability as defined in 5.8.3. See Clause 6. bMaintenance consists of cleaning, tightening, adjusting, lubricating, and dressing of contacts, and so on, as recommended by the manufacturer under usual service conditions. Maintenance intervals are usually based on both an elapsed time and a number of operations, whichever occurs sooner. In determining maintenance intervals for particular applications, consideration must be given to actual conditions prevailing at the installation site. Refer to Clause 4 for service conditions and to Clause 7 for general application conditions. The numbers of operations specified in Column 2 are based on usual service conditions. When used as a guide for field application, they define maximum maintenance intervals. c When closing and opening no-load. d With rated control voltage applied (see Table 10). e Frequency of operation (see 5.10). f Requirements are based on specified maintenance intervals in accordance with Column 2. g No functional part shall have been replaced prior to completion of the specified number of operations. hAfter completion of the specified number of operations, the circuit breaker shall withstand 75% of its rated power frequency withstand voltage, and the resistance of the current carrying circuit from terminal to terminal measured with a current of at least 100 A flowing shall not have increased by more than the amount specified by the manufacturer compared with the value for the circuit breaker when new. Under these conditions, the circuit breaker is considered capable of carrying the rated continuous current, at power frequency, without injurious heating until maintained and of performing one interruption at rated short-circuit current or a related capability. After completion of this series of operations, functional part replacement and general maintenance may be necessary (see 6.2.8.3). iIf a short-circuit operation occurs before the completion of the listed operations, maintenance is recommended and possible functional part replacement may be necessary depending on previous duty, fault magnitude, and expected future operations. Replace 5.10.2 title (old 5.10.1) with the following title:

5.10.2 Inherent TRV for load current switching

Change the existing paragraph as follows: The inherent TRV for out-of-phase current switching is the reference voltage that constitutes the limit of the inherent transient recovery voltage of circuits, which the circuit breaker shall be capable of withstanding under out-of-phase switching conditions and shall be defined by an oscillatory wave-shape having a the TRV rate, time delay, and crest peak voltage (E2) as listed in Table 8a (see also 7.3.9.2). The formula and method for determining the time-to-crest peak (T2) are given in 7.3.6.3 and Figure 15. Insert the following paragraph after the current one: Table 8 provides the preferred values of the inherent TRV parameters for load current switching. If the circuit breaker requires that the inherent TRV be modified by the addition of capacitors, then the amount of equivalent capacitance required shall be given in the test report and on the nameplate. It is recognized that connecting a shielded cable or a cable bus between the generator and the circuit breaker may provide this capacitance. Please refer to 6.2.3.7.3 for additional information.





Replace Table 8 with the following: Table 8—TRV parameters for load current switching

Inherent TRV

Generator rating



TRV rate (kV/µs)


1 10 –50 1.20 V 0.92 V 0.9

2 51–100 1.08 V 0.92 V 1.0

3 101–400 0.91 V 0.92 V 1.2

4 401–800 0.77 V 0.92 V 1.4

5 801 or more 0.62 V 0.92 V 1.6

NOTES:

1—Time delay shall be equal to or less than 1 μs. 2—See 6.2.8.2 of IEEE Std C37.013-1997 for test voltage values.


5.12 Out-of-phase current switching ability

5.12.3 Inherent TRV for out-of-phase current switching

Change the existing paragraph as follows: The inherent TRV for out-of-phase current switching is the reference voltage that constitutes the limit of the inherent transient recovery voltage of circuits, which the circuit breaker shall be capable of withstanding under out-of-phase switching conditions and shall be defined by an oscillatory wave-shape having a the TRV rate, time delay, and crest peak voltage (E2) as listed in Table 9a (see also 7.3.9.2). The formula and method for determining the time-to-crest peak (T2) are given in 7.3.6.3 and Figure 15. Insert the following paragraph after the current one: If the circuit breaker requires that the inherent TRV be modified by the addition of capacitors, then the amount of equivalent capacitance required shall be given in the test report and on the nameplate. It is recognized that connecting a shielded cable or a cable bus between the generator and the circuit breaker may provide this capacitance. Please refer to 6.2.3.7.3 for additional information.





Replace Table 9 with the following: Table 9—TRV parameters for out-of-phase current switching

Inherent TRV

Generator rating



TRV rate (kV/µs)


1 10 –50 0.98 V 2.6 V 3.0

2 51–100 0.89 V 2.6 V 3.3

3 101–400 0.72 V 2.6 V 4.1

4 401–800 0.63 V 2.6 V 4.7

5 801 or more 0.57 V 2.6 V 5.2

NOTES:

1—Time delay shall be equal to or less than 0.5 μs.


6. Tests

6.2.3.7.3 Recovery voltage

Change the item b) as follows: b) Transient recovery voltage. The inherent circuit TRV (unmodified by the generator circuit

breaker) shall be such as to give the applicable oscillatory wave-shape with values as listed in Table 5 for the rated short-circuit currents. Table 6 is included for information on TRV values for generator-source short-circuit currents.

Asymmetrical current-interrupting capabilities shall be demonstrated using test circuits capable of producing the rated TRV envelopes unmodified by the generator circuit breaker when a symmetrical current is interrupted. The parameters of the test circuit shall be adjusted so as to produce the specified rated inherent circuit TRV.

The actual TRV measured during test may differ from the inherent circuit TRV due to the influence of the generator circuit breaker (its resistors and/or capacitors).

The actual TRV measured during the test may differ from the inherent TRV of the test circuit measured before the test without the circuit breaker present. This is because the circuit breaker itself can influence the TRV due to its resistors and/or capacitors, or other reasons.

Change the title to 6.2.3.8.3 as follows:

6.2.3.8.3 Unit tests

Change the existing paragraph as follows: See 4.6.6.3 of IEEE Std C37.09-19794.6.6.3 or 4.8.2.3 of IEEE Std C37.09-1999.





Change the title to 6.2.3.8.5 as follows:

6.2.3.8.5 Pre-tripped tests

Change the existing paragraph as follows: See 4.6.6.5 of IEEE Std. C37.09-1979 4.6.6.5 or 4.8.2.4 of IEEE Std C37.09-1999.

6.2.3.9 Suggested short-circuit performance data form

Change the existing paragraph as follows: Test data are preferably presented in a form with an accompanying tabulation of pertinent data similar to that shown in Table 3 of IEEE Std C37.09-1979, Table 3or Annex A of IEEE Std C37.09-1999, where applicable.

6.3.1.2 Porcelain components

Change the existing paragraph as follows: If porcelain is used in the generator circuit breaker, the porcelain shall satisfy 5.4.2 in IEEE Std. C37.09-1979 or 5.4.2 in IEEE Std C37.09-1999, or any other international or national standard as appropriate.

6.3.4 Leakage tests

Change the existing paragraph as follows: Systems containing gas under pressure shall be placed under normal operating pressure and the supply of additional gas cut off by removal of compressor power or by closing a valve to a common supply. The leakage must not cause a decrease in pressure with time that exceeds a rate specified by the manufacturer. Refer to 5.7 and 5.8 of IEEE Std C37.09-1999. Change the title to 6.4.1 as follows:

6.4.1 Leakage tests (after delivery)

Change the existing paragraph as follows: This test is made on the completely assembled generator circuit breaker with its pumps, compressor plant, associated valves, field piping, and any other devices required by the design of the particular system to operate satisfactorily. With the apparatus completely assembled, the pressure shall be raised to the normal operating pressure to all parts of the system that can be subjected to this service pressure. Closing a valve to the common supply shall then cut off the supply of additional air or gas. The leakage must not cause a decrease in pressure with time, which exceeds a rate specified by the manufacturer. Refer to 5.7 and 5.8 of IEEE Std C37.09-1999.





7. Application guide

7.3.5.2 Rated short-circuit current

Insert the following text at the end of the existing paragraph: It is to be noted that, if the short-circuit performance capability of a generator circuit breaker design has been demonstrated for a certain generator-source fault rating, or for a certain system-source fault rating, then that proven short-circuit performance capability also serves to demonstrate the capability for less severe generator-source faults, or for less severe system-source faults. However, it is important to remember that parameters for generator circuit faults include short-time current withstand, transient recovery voltage (TRV), close-and-latch current, %dc component and most severe switching conditions, as well as the symmetrical current, for both system-source faults and generator-source faults. Proven capabilities for all of these parameters shall be demonstrated to meet or exceed the respective requirements for the intended application.

7.3.6.2.1.1 System-source fed faults

Insert the following text at the end of the existing paragraph: In the special case where generator circuit breaker is connected to the step-up transformer by shielded cables, the additional capacitance of the cables modifies the inherent TRV, as illustrated in Annex B.

7.3.6.3 Rated inherent transient recovery voltage

Insert the following new paragraph after the existing last paragraph: The reference lines for the inherent transient recovery voltage wave of the test circuit shall at no time be below the specified reference lines required for the application.

NOTE—It is stressed that the extent by which the TRV envelope of the test circuit may exceed the specified reference line requires the consent of the manufacturer.

8. Bibliography

Insert the following new references in alphanumeric order: [B7] Dufournet, D. and Montillet, G. F., “Transient Recovery Voltage Requirements for System-Source Fault Interrupting by Small Generator Circuit Breakers,” IEEE Transactions on Power Delivery, vol. 17, no. 2, pp. 474–478, April 2002.

[B8] IEC 62271-200 First Edition (2003-11), High voltage switchgear and controlgear—Part 200:AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV.9

[B9] IEEE C37.20.2TM-1999 (Reaff 2004), IEEE Standard for Metal-Clad Switchgear.10

9 IEC publications are available from the Sales Department of the International Electrotechnical Commission, Case Postale 131, 3, rue de Varembé, CH-1211, Genève 20, Switzerland/Suisse (http://www.iec.ch/). IEC publications are also available in the United States from the Sales Department, American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, NY 10036, USA (http://www.ansi.org/). 10 IEEE publications are available from the Institute of Electrical and Electronics Engineers, Inc., 445 Hoes Lane, Piscataway, NJ 08854, USA (http://standards.ieee.org/).





Insert the following new Annex B after Annex A:

Annex B

(informative)

For generator circuit breakers connected to the step-up transformer by shielded cables—an example of the effects of added capacitance on TRV requirements for a system-source fault

The Inherent Transient Recovery Voltage (TRV) requirements for generator circuit breakers under system-source fault conditions are listed in Table 5a. They are based on the assumption that the step-up transformer will be connected to the generator circuit breaker by bus. Although this assumption is true for many applications, several smaller installations also exist where the connection is made with shielded cables. One way of determining the effects of the capacitance added by shielded cables on the TRV that the circuit breaker would experience while trying to clear a three-phase, ungrounded fault current, fed from the step-up transformer, has been described by Dufournet and Montillet [B7]. This method illustrates that the added capacitance of shielded cables used to connect the transformer to the generator circuit breaker can have two significant effects on the TRV, as follows:

a) The rate of rise of the recovery voltage (RRRV), or “TRV rate,” is reduced.

b) The TRV peak E2 is increased.

The significance of these effects can be illustrated in the following four figures:

⎯ Figure B.1 shows the effect on the TRV rate, which is associated with switching faulted transformers rated in the range of 65.5–100 MVA.

⎯ Figure B.2 shows the effect on E2, the TRV peak, which is associated with switching faulted transformers rated in the range of 65.5–100 MVA.

⎯ Figure B.3 shows the effect on the TRV rate, which is associated with switching faulted transformers rated in the range of 10–50 MVA.

⎯ Figure B.4 shows the effect on E2, the TRV peak, which is associated with switching faulted transformers rated in the range of 10–50 MVA.

NOTE—These calculations are illustrative of a method to evaluate the effects of capacitance associated with cable connections. Certain other assumptions, such as the transformer short-circuit impedance of 14%, although consistent with the other illustrative calculations in IEEE Std C37.013, are not intended to be completely representative of all applications. Clearly, the user must carefully consider all the parameters of the particular circuit and determine the required TRV values based on the actual parameters of the circuit in the generator circuit breaker application under consideration.





Figure B.1—TRV rates for system-fed faults: transformers rated from 65.5 MVA to 100 MVA





Figure B.2—TRV peak (E2) multipliers for system-fed faults: transformers rated from

65.5 MVA to 100 MVA

Figure B.3—TRV rates for system-fed faults: transformers rated from 10 MVA to 50 MVA





Figure B.4—TRV peak (E2) multipliers for system-fed faults: transformers rated from 10 MVA to 50 MVA
