20A-1946 - AIEE Proposed Standard for Low-Voltage Air Circuit Breakers (Published for one year trial use).pdf

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1、IEEE STANDARDS JIL ARC HIV Lb no NOT REMOVE Proposed Standard for LOW-VOLTAGE AIR CIRCUIT BREAKERS (Published for one year trial use) Published by THE AMERICAN INSTITUTE OF ELECTRICAL ENGINEERS 33 West Thirty-ninth Street, New York 18 Development of the Standards of the American Institute of Electri

2、cal Engineers Recognizing the importance in the development of electrical engineering, of standardiza tion in the electrical field, the AIEE in 1898 appointed- a Committee on Standardization, consisting of seven members having qualifications and experience from designing, manufac turing and operatin

3、g standpoints. The report of this Committee was accepted at a meeting of the Institute in June 1899. Experience gained in applications of the standards and further developments in electric apparatus and methods showed the necessity of revision, and a committee was appointed which after consultation

4、with manufacturing and operating engineers presented the first revised report on Standardization Rules of the AIEE in June 1902. The next revision was undertaken by a committee of ten, which presented its report in May 1906. In September 1906, a Standards Committee of eleven members was appointed fo

5、r further revision, and its report was presented in June 1907. The appreciation of the importance and value of standardization resulted in the forma tion of a Standing Committee, with the title of Standards Committee of the AIEE. This became effective in the Constitution of June 1907. The scope and

6、amount of work necessitated increasing the number of members from time to time until in 1922 there were 37 members divided into a number of subcommittees specializing on various subjects. AIEE Standards published in a single volume as each revision was adopted were generally accepted as standards of

7、 the electrical industry of the United States since the adoption of the first report in 1899. Subsequent reports on standards were made and pub lished, in some cases in several editions. The dates of adoption by the Board of Directors of such reports are as follows: June 20, 1902; June 21, 1907; Jun

8、e 27, 1912; July 10, 1914; June 30, 1915; June 28, 1916; November 8, 1918; October 8, 1920, and June 29, 1922. On June 29, 1922, in view of the increasing complexity of the work, a reorganization of the Standards Committee was effected, and a working organization established which pro vided for an i

9、ncrease in standardization work and for the appointment on Working Commit tees of the Standards Committee of non-Institute members. The present plan under which the Institute Standards are being issued involves the sepa ration of the complete body of standards into more than forty sections, each pub

10、lished as a separate pamphlet and dealing with a specific subject. Each section of the standards has been formulated either by a subcommittee of the Standards Committee which was made as rep resentative as possible for the work in hand, by an AIEE Technical Committee or subcom mittee, or by a Sectio

11、nal Committee organized according to the procedure of the American Standards Association. The division of the standards into a number of separate publications simplifies the process of keeping the standards revised to conform with the latest develop ment and enables those interested in a particular

12、field to obtain in concise form the material relating to that field. In framing the Institute Standards the chief purpose has been to define terms and conditions which characterize the rating and behavior of electric machinery and apparatus, with special reference to the conditions of acceptance tes

13、ts. The AIEE Standards Committee takes this occasion to draw attention to the value of suggestions based upon experience gained in the application of the standards to general practice. Any suggestions looking toward improvement in the standards will be welcomed for the guidance of the Committee in p

14、reparation of future editions, and should be communicated to the Secretary of the AIEE Standards Committee, 33 West 39th Street, New York 18, N. Y. 2 TABLE OF CONTENTS Scope , 5 Service Conditions 5 Definitions 5 General 6 Qualifying Terms 7 Ratings 9 Heating 11 Conditions and Methods of Making the

15、Temperature Test 11 Dielectric Tests , 12 Nameplate Markings 13 ACKNOWLEDGMENT The Institute wishes to acknowledge its indebtedness to those who have so freely given their time and knowledge and have conducted experimental work on which many of the AIEE Standards are based. This proposed standard wa

16、s prepared by a Working Group of the Circuit Breakers and Assembled Switchgear Subcommittee of the AIEE Committee on Protective Devices. The personnel of this Working Group is as follows: J. D. WOOD, Chairman A. H. BEILER A. C. BOISSEAU E. A. CHILDERHOSE F. W. CRAMER G. G. GRISSINGER J. E. HOUSLEY 4

17、 Standard of the American Institute of Electrical Engineers LOW-VOLTAGE AIR CIRCUIT BREAKERS SCOPE This standard applies to all air circuit breakers with interrupting rating over 10,000 amperes as follows: A. Air circuit breakers 1500 volts or less alternating current and 3000 volts or less direct c

18、urrent. Special purpose air circuit breakers for the con trol of generators, rectifiers and for heavy duty applications, in addition to meeting these stand ards generally have other requirements not yet standardized. B. All field discharge breakers comprising air circuit breaker contact elements wit

19、h field discharge con tacts added, of any ampere rating single pole or multipole. C. Air circuit breakers assembled as integral units in supporting and enclosing housings of insulation material for voltage ratings up to and including 600 volts alternating current, 250 volts direct cur rent. D. Air c

20、ircuit breakers, when in individual enclosures usually built of steel for separate mounting. SERVICE CONDITIONS 20-1 Usual Service ConditionsEquipment con forming to this standard shall be suitable for operation at its standard rating, provided that: (a) The temperature of the cooling air (ambient t

21、emperature) does not exceed 40C if the equip ment has copper-to-copper contacts or equivalent. (b) The temperature of the cooling air (am bient temperature) does not exceed 55C if the equipment has all contacts silver surfaced or equivalent, and in addition has all conducting joints, including termi

22、nal connections, either (1) soldered or silver surfaced and separately held mechanically, or (2) brazed, welded or silver soldered and provided that such operation does not result in temperatures in excess of 90C for Class O, 105 C for Class A or 130C for Class B insulations. (c) The altitude does n

23、ot exceed 3300 ft. (1000 meters). 20-2 Unusual Temperature & Altitude Service Con ditionsThe application of equipment at higher ambient temperatures or at higher altitudes than specified in Usual Service Conditions shall be con sidered as special. Standard equipment may be applied at higher ambient

24、temperatures or at higher alitudes than specified, but its performance may be affected and special consideration should be given to these ap plications. 20-3 Other Conditions Which May Affect Design & ApplicationWhere other unusual conditions ex ist they should be brought to the attention of those r

25、esponsible for the design and application of the equipment. Examples of such conditions are: (a) Damaging fumes or vapors, excessive or abrasive dust, explosive mixtures of dust or gases, steam, salt spray, excessive moisture or dripping water, etc. (b) Abnormal vibration, shocks, or tilting. (c) Ex

26、cessively high or low temperature. (d) Unusual transportation or storage con ditions. (e) Unusual space limitations. (/) Unusual operating duty, frequency of op eration, difficulty of maintenance, poor wave form, unbalanced voltage, special insulation require ments, etc. 20-4 Applications at Altitud

27、es Greater than 3300 Feet (1000 meters)Circuit breakers may be used at altitudes greater than 3300 feet (1000 meters) provided their current rating and voltage are mul tiplied by the following factors to obtain the voltage and current at which the application may be made. Correction Factors Altitude

28、 Current Voltage 3300 feet (1000 meters) 1.00 1.00 5000 feet (1500 meters) 0.99 0.95 10000 feet (3000 meters) 0.96 0.80 20000 feet (6000 meters) 0.90 0.56 For other values see AIEE Standard No. IB DEFINITIONS Definitions as given herein apply specifically to the apparatus treated in this standard. F

29、or addi-5 tional definitions see American Standard Defini tions of Electrical TermsC42. The three part numbers (following the titles of some of the definitions) included in this standard, indicate the number of the corresponding definitions in C42. Where numbers only appear refer to C42 for definiti

30、on. General 20-50 Circuit Breaker (20.15.005) ChangedA cir cuit breaker is a device for closing and interrupt ing a circuit between separable contacts under normal or abnormal conditions. Note: Ordinarily circuit breakers are required to operate relatively infrequently, although some classes of brea

31、kers are suitable for frequent operation. Note: Normal indicates the interruption of currents not in excess of the rated continuous current of the circuit breaker. Abnormal indicates the interruption of currents in excess of such rated continuous currents such as short cir cuits. 20-51 Air Circuit B

32、reaker (20.15.015)An air cir cuit breaker is a circuit breaker in which the interruption occurs in air. 20-52 Molded Case Breaker (Not in C42) A molded case circuit breaker is a breaker assem bled as an integral unit in a supporting and en closing housing of insulation material. Note: The overcurren

33、t tripping means may be of the thermal type, magnetic type, or a combination of both. 20-53 Individually Enclosed Air Circuit Breaker (Not in C42)An individually enclosed air circuit breaker is a circuit breaker that has all live parts on the front of the mounting base or frame en closed in a case w

34、ith provision for external opera tion and has an enclosure on the rear to enclose the studs. Knockouts or other openings are available for connections. 20-54 Field Discharge Breaker (20.10.055) Changed A field discharge breaker is an air circuit breaker, having auxiliary contacts for short-cir cuiti

35、ng the field of a generator or motor through a resistor at the instant preceding the opening of the circuit breaker contact. 20-56 Operating Voltage (20.05.171)The operating voltage of a circuit breaker is the rms voltage of the system on which it is to be operated. 20-57 Recovery Voltage (Not in C4

36、2)Recovery voltage is the voltage which occurs across the terminals of a circuit-interrupting device upon in terruption of the current. (a) Normal - Frequency Recovery Voltage (20.05.172) ChangedThe normal-frequency re covery voltage is the normal frequency rms volt age which occurs across the termi

37、nals of a cir cuit-interrupting device after the interruption of the current and after high-frequency transients have subsided. Note: For determination of the normal-frequency recov ery voltage, see American Standard Methods for Determin ing the RMS Value of a Sinusoidal Current Wave and a Normal Fr

38、equency Recovery Voltage, C37.S. (b) Transient Recovery Voltage (20.05.173) ChangedThe transient recovery voltage is the | voltage transient which occurs across the ter minals of a circuit-interrupting device upon in terruption of the current. Note: This transient usually exists for only a fraction

39、of a cycle. In a multipole interrupting device, the term is usually applied to the voltage across the first pole to clear. (1) Circuit Transient Recovery Voltage The circuit transient recovery voltage is the transient recovery voltage character izing the circuit and obtained with 100 percent normaj-

40、frequency recovery volt age, a symmetrical current, and no modi fying effect of the breaker. This voltage indicates the inherent sever ity of circuits with respect to recovery voltage phenomena. (2) Modified Circuit Transient Recovery VoltageThe modified circuit transient re covery voltage is the ci

41、rcuit transient recovery voltage modified in accordance with the normal-frequency recovery volt age and the asymmetry of the current wave obtained on a particular interruption. This voltage indicates the severity of the par ticular interruption with respect to recov ery voltage phenomena. (3) Test T

42、ransient Recovery VoltageThe test transient recovery voltage is the tran sient recovery voltage which actually oc curs across the terminals of a circuit inter rupting device on a particular interrup tion. Note: This is the modified circuit transient recovery volt age with whatever distortion may be

43、introduced by the circuit interrupting device. (c) Transient Recovery Voltage Rate (20-05.174) ChangedThe transient recovery voltage rate is the rate at which voltage rises across the terminals of a circuit-interrupting device upon in terruption of the current. It is usually determined by dividing t

44、he voltage at one of the crests of the transient re covery voltage by the time from current zero to that crest. In case no definite crest exists the rate is taken to some arbitrarily chosen value usually selected as a certain percentage of the crest value of the normal frequency recovery voltage. Th

45、e transient recovery rate may be either a circuit transient recovery voltage rate, a modified circuit transient recovery voltage rate, or a test transient recovery voltage rate according to the type of transient from which it is obtained. When giving test transient recovery volt age rates, the metho

46、d of determining the time of current zero should be definitely stated. For determination of transient recovery voltage rates, see American Standard Test Code for Power Circuit Breakers, C37.9. Qualifying Terms 20-60 Automatic Tripping (Automatic Opening) (20.15.095) ChangedAutomatic tripping is the

47、opening of a circuit breaker under predetermined or other conditions without the intervention of an operator. The devices to accomplish this are integral with the circuit breaker and are termed: 1. Instantaneous Overcurrent TripAn in stantaneous overcurrent trip is one which func tions above a prede

48、termined current without any purposely delayed action. 2. Instantaneous Short-Circuit TripAn in stantaneous short-circuit trip is one which func tions without purposely delayed action, at a value of overcurrent above which magnetic and thermal injury to the circuit breaker may occur. 3. Delayed Over

49、current Trip A delayed overcurrent trip is one which functions above a predetermined overcurrent with a purposely de layed action. a. Mechanically Delayed Overcurrent Trip A mechanically delayed overcurrent trip is one whose purposely delayed function is per formed by a mechanical device. b. Fluidly Delayed Overcurrent Trip A fluidly delayed overcurrent trip is ohe whose purposely delayed function is performed through fluid by: 1. Displacement 2. Adhesion c. Thermally Delayed Overcurrent TripA thermally delayed overcurrent trip