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IEEE C37.18

Standard Enclosed Field Discharge Circuit Breakers for Rotating Electric Machinery

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Organization: IEEE
Publication Date: 1 January 1979
Status: active
Page Count: 30
scope:

Foreword

(This Foreword is not a part of ANSI/IEEE C37.18-1979, American National Standard Enclosed Field Discharge Circuit Breakers for Rotating Electric Machinery.)

This standard was first published in 1962 as IEEE Publication No 90 for trial use. It was also published as NEMA Std SG3-1965, Low-Voltage Power. After a period of industry use the material was reviewed and revised and published as USA Std 37.18-1968 (R1975), Requirements for Field Discharge Circuit Breakers for Rotating Electric Machinery, and USA Std C37.16a-1968, Supplement to USA Std C37.16-1963, Preferred Ratings and Related Requirements for Low-Voltage Power Circuit Breakers. This revision of the material, ANSI/IEEE C37.18-1979, which replaces ANSI C37.18-1968, was developed by the IEEE Working Group of the Low-Voltage Switchgear Devices Subcommittee.

The major revisions which have been made in updating this standard to reflect the changing state of the art are the addition of material concerned with solid-state sources of excitation and additional ratings. The preferred ratings and related requirements are still contained in Tables 7, 7A, and 14 of ANSI C37.16-1979, Preferred Ratings, Related Requirements, and Application Recommendations for Low-Voltage Power Circuit Breakers and AC Power Circuit Protectors (revision and consolidation of C37.15-1954 and C37.16-1970); although Section 7, Test Procedures, and Section 9, Application have been extensively revised to reflect present day requirements.

This publication represents standard practice in the United States relating to field discharge circuit breakers for use in field circuits of rotating electric machinery such as generators, motors, synchronous condensers, or exciters. American National Standards covering additional requirements are: ANSI C37.16-1979; Switchgear Assemblies, Including Metal-Enclosed Bus, ANSI/IEEE C37.20-1969, Definitions for Power Switchgear, ANSI C37.100-1972 (IEC 50-16) (IEC 277); Standard Techniques for High-Voltage Testing, IEEE Std 4-1978, (IEC 52).

Molded-case circuit breakers are covered by other standards but in some instances may be able to meet the requirements of this standard.

The Standards Committee on Power Switchgear, C37, which reviewed and approved this standard, had the following personnel at the time of approval:

C. L. Wagner, Chair

J. P. Lucas, Secretary

J. E. Beehler (Executive Vice-Chairman of High Voltage Switchgear Standards)

W. E. Laubach (Executive Vice-Chairman of Low Voltage Switchgear Standards)

S. H. Telander (Executive Vice-Chairman of IEC Activities)

Organization Represented

Association of American Railroads 

Association of Iron and Steel  Engineers

Electric Light and Power  Group

Name of Representative

Vacant

J. M. Tillman

K. G. Adgate

J. E. Beehler

R. L. Capra (Alt)

H. G. Darron

H. F. Frus

K. D. Hendrix

R. L. Lindsey (Alt)

E. E. Ramm (Alt)

F. R. Solis 

Institute of Electrical and Electronics Engineers

M. J. Beachy (Alt)

R. N. Bell (Alt)

H. H. Fahnoe

R. E. Friedrich

M. J. Maier

C. A. Mathews (Alt)

D. C. Musgrave (Alt)

G. W. Walsh

H. F. White

National Electrical Manufacturers Association

A. P. Colaiaco

R. W. Dunham

D. G. Portman

G. A. Wilson

W. R. Wilson

Tennessee Valley Authority

Robert C. St. Clair

Testing Laboratory Group

L. Frier

E. J. Huber

R. W. Seelbach (Alt)

U.S. Department of the Army

Robert H. Bruck

U.S. Department of the Interior Bureau of Reclamation

Edward M. Tomsic

U.S. Department of Defense, Defense Communications Agency

Vacant

U.S. Department of the Navy, Naval Facilities Engineering Command

D. M. Hannemann

The Working Group of the IEEE Low-Voltage Switchgear Devices Subcommittee responsible for the current revivsion are:

M. B. Fornwalt, Chair

H. H. Connelley, Secretary

R. J. Alton

L. L. Baird

J. M. Clark

M. L. Crenshaw

R. E. Gorman

W. J. Lordeon

R. A. McMaster

The members of the IEEE Low-Voltage Switchgear Devices Subcommittee who reviewed and approved this standard are:

R. N. Bell, Chair

H. H. Connelley, Secretary

R. J. Alton

L. L. Baird

A. N. Eliasen

W. H. Ferguson

E. J. Huber

J. J. Komisky

R. A. McMaster

W. A. Mathews

V. A. Mortenson

F. J. Shields

J. Stewart

J. R. Truitt

J. P. Werner

When this standard was approved December 9, 1976, the IEEE Standards Board had the following membership:

William R. Kruesi, Chair

Irvin N. Howell, Jr, Vice Chair

Ivan G. Easton, Secretary

William E. Andrus

Jean Jacques Archambault

Dale R. Cochran

Warren H. Cook

Louis Costrell

Jay Forster

Joseph L. Koepfinger

Irving Kolodny

Benjamin J. Leon

Anthony C. Lordi

John P. Markey

Thomas J. Martin

Donald T. Michael

Voss A. Moore

William S. Morgan

William J. Neiswender

Gustave Shapiro

Ralph M. Showers

Robert A. Soderman

Leonard W. Thomas, Sr

Charles L. Wagner

William T. Wintringham†

Scope 

This standard applies to all low-voltage power-circuit breakers that are intended for use in field circuits of apparatus such as generators, motors, synchronous condensers, or exciters and embodying contacts for establishing field discharge circuits.

NOTE - In this standard, the use of the term "circuit breaker" shall be considered to mean "field discharge circuit breaker used in enclosures for rotating electric machinery."

In performing their function of interrupting field circuits of rotating electric machinery, field discharge circuit breakers are subject to the following conditions not met within the interruption of ordinary direct-current power circuits.

1) In alternating-current machine field circuits, in addition to the problems usually encountered in switching highly inductive direct-current circuits, there is superimposed upon the voltage generated by the exciter, a voltage induced in the field windings by the transient current in the machine armature under alternating-current short-circuit conditions. These result in large pulsating currents in the field circuit as illustrated in Fig 1.

2) Due to the large amount of magnetic energy stored in the machine field circuit, the interruption of the circuit results in an unusually high transient voltage under alternating-current short-circuit conditions, unless special means are provided for dissipating the energy.

3) A discharge resistor must be connected across the terminals of the machine field by the discharge contacts of the circuit breaker just prior to disconnecting the field from its excitation source in order to provide for dissipation of the stored energy of the machine field and to minimize the transient voltage. The voltage across the field discharge circuit breaker main contacts following interruption of the excitation source current is illustrated in Fig 2.

4) In addition to the above conditions, there is the usual direct-current short-circuit condition wherein the field circuit may become short-circuited.

To cope with these unique conditions, this standard for field discharge breakers has been developed to establish the rating structure and test requirements not encountered in other ANSI Standards 1 which apply to other low-voltage circuit breakers.

The dielectric test values given in Table 7A, ANSI C37.16-1979, Preferred Ratings, Related Requirements, and Application Recommendations for Low-Voltage Power Circuit Breakers and AC Power Circuit Protectors, reflect the change in dielectric test requirements in ANSI C50.13-1977 Requirements for Cylindrical Rotor Synchronous Generators.

1 American National Standards are available front the American National Standards Institute, 1430 Broadway, New York, N.Y. 10018.

Document History

IEEE C37.18
January 1, 1979
Standard Enclosed Field Discharge Circuit Breakers for Rotating Electric Machinery
Foreword (This Foreword is not a part of ANSI/IEEE C37.18-1979, American National Standard Enclosed Field Discharge Circuit Breakers for Rotating Electric Machinery.) This standard was first...
January 1, 1979
Standard Enclosed Field Discharge Circuit Breakers for Rotating Electric Machinery
A description is not available for this item.
January 1, 1979
Standard Enclosed Field Discharge Circuit Breakers for Rotating Electric Machinery
A description is not available for this item.

References

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