1、NEMA Standards PublicationNational Electrical Manufacturers AssociationANSI/NEMA AB 3-2013Molded Case Circuit Breakers and Their ApplicationANSI/NEMA AB 3-2013 American National Standard Molded Case Circuit Breakers and Their Application Secretariat National Electrical Manufacturers Association Appr
2、oved February 25, 2013 Published March 1, 2013 American National Standards Institute, Inc. AB 3-2013 Page ii Copyright 2013 by National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged
3、in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. American National Standards Institute (ANSI) standards and guideline publications,
4、 of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process a
5、nd establishes rules to promote fairness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NE
6、MA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaran
7、ty or warranty, expressed or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any i
8、ndividual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by
9、 any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic
10、 covered by this publication may be available from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify
11、, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statement of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the s
12、tatement. AB 3-2013 Page iii Copyright 2013 by National Electrical Manufacturers Association FOREWORD This standards publication is intended to provide a basis of common understanding within the electrical community concerning the proper application of molded case circuit breakers. User needs have b
13、een considered throughout the development of this publication. Proposed or recommended revisions should be submitted to: Senior Technical Director, Operations National Electrical Manufacturers Association 1300 North 17th Street Rosslyn, VA 22209 This standards publication was developed by the Molded
14、 Case Breaker product group of the NEMA Low Voltage Distribution Equipment (LVDE) Section. Section approval of the standard does not necessarily imply that all section members voted for its approval or participated in its development. At the time it was approved, the Molded Case Breaker product grou
15、p was composed of the following members: ABB Inc. New Berlin, WI Eaton Electrical Pittsburg, PA GE Industrial Solutions Plainville, CT Siemens Industry, Inc. Norcross, GA Schneider Electric USA Palatine, IL AB 3-2013 Page iv Copyright 2013 by National Electrical Manufacturers Association TABLE OF CO
16、NTENTS Page FOREWORD iii Section 1 GENERAL 1.1 Scope . 1 1.2 References . 1 1.3 Definitions 3 1.4 Abbreviations and Symbols 8 1.5 General Applications 9 1.5.1 Purpose of Circuit Breakers 9 1.5.2 Purpose of Molded Case Switches . 9 1.6 Field Testing . 9 SECTION 2 AVAILABLE TYPES OF MOLDED CASE CIRCUI
17、T BREAKERS 2.1 General Usage Categories. 11 2.1.1 Residential . 11 2.1.2 Industrial/Commercial 11 2.2 Tripping Means 11 2.2.1 Thermal-Magnetic 11 2.2.2 Hydraulic-magnetic 11 2.2.3 Electronic (Solid-State) 11 2.3 Specific Purpose Categories 12 2.3.1 Remotely Operated Circuit Breakers . 12 2.3.2 Integ
18、rally-Fused Circuit Breakers 12 2.3.3 Current-Limiting Circuit Breakers 12 2.3.4 Switching Duty Circuit Breakers (SWD) 12 2.3.5 Instantaneous Trip Only Circuit Breakers (Motor Circuit Protector or Circuit Interrupter) 15 2.3.6 Heating, Air Conditioning, and Refrigeration Circuit Breakers (HACR) . 15
19、 2.3.7 Marine Circuit Breakers . 15 2.3.8 Naval Circuit Breakers . 15 2.3.9 Mining Circuit Breakers 15 2.3.10 High Intensity Discharge Lighting Circuit Breakers (HID) . 15 2.3.11 Ground Fault Circuit Interrupter (GFCI) Circuit Breakers . 15 2.3.12 Circuit Breaker with Equipment Ground Fault Protecti
20、on . 16 2.3.13 Classified Circuit Breakers 16 2.3.14 Circuit Breakers with Secondary Surge Arrester 16 2.3.15 Circuit Breakers with Transient Voltage Surge Suppressor 16 2.3.16 Circuit Breakers for Use With Uninterruptible Power Supplies . 16 2.3.17 Arc-Fault Circuit Interrupter (AFCI) Circuit Break
21、ers 16 2.4 Other Applications 16 2.5 Special Purpose Circuit Breakers 16 SECTION 3 AVAILABLE VARIATIONS IN MOLDED CASE CIRCUIT BREAKERS 3.1 Constructional Variations . 17 3.1.1 Circuit Breaker 17 3.1.2 Frame 17 3.1.3 Interchangeable Trip Unit 17 3.1.4 Mechanism 17 AB 3-2013 Page iii Copyright 2013 b
22、y National Electrical Manufacturers Association 3.1.5 Pole . 17 3.1.6 Accessories . 17 3.2 Installation Variations . 18 3.2.1 External Conductor Connectors 18 3.2.2 Mounting Arrangements 18 3.3 Handle Orientation . 19 3.4 Reverse Feed Circuit Breakers 19 SECTION 4 MOLDED CASE CIRCUIT BREAKER RATINGS
23、 4.1 Ampere Ratings . 20 4.2 Voltage Ratings 20 4.3 Interrupting Ratings 21 4.4 Frequency 21 4.5 Power Factor Considerations . 21 SECTION 5 SELECTION OF MOLDED CASE CIRCUIT BREAKERS 5.1 Preliminary Considerations 23 5.1.1 Electrical Parameters 23 5.1.2 User Requirements . 23 5.1.3 Environmental Cond
24、itions . 23 5.1.4 National Electrical Code 25 5.2 General Considerations for Molded Case Circuit Breaker Application 26 5.2.1 General Requirements 26 5.2.2 Main Circuit Breaker . 26 5.2.3 Feeder Circuit Breaker 26 5.2.4 Branch Circuit Breaker 27 5.3 Load Requirement Considerations 29 5.3.1 Continuou
25、s Duty, General Purpose Load . 30 5.3.2 Lighting Loads . 30 5.3.3 Heating, Air Conditioning, and Refrigeration Loads 30 5.3.4 Motor Loads 30 5.4 Specific Considerations for Molded Case Circuit Breaker Applications . 30 5.4.1 Conductor Selection 30 5.4.2 Terminations . 31 5.4.3 Single-Phasing Protect
26、ion . 31 5.4.4 Time-Current Curves 31 5.4.5 Selective Coordination 40 5.4.6 Series Application . 43 5.4.7 Dynamic Impedance . 44 5.4.8 Capacitor Switching 45 5.4.9 Motor Loads 45 5.4.10 Nuclear Power Generating Station Equipment Qualifications . 46 5.5 Other Considerations for Specific Applications
27、46 5.5.1 Current-Limiting 46 5.5.2 Ground Fault Protection 47 5.5.3 Molded Case Switches 49 5.5.4 Circuit Breakers Used on DC Systems . 49 5.5.5 Arcing Fault Protection (Circuit Breaker Type AFCI) 50 Appendix A UL REQUIREMENTS FOR MOLDED CASE CIRCUIT BREAKERS . 52 AB 3-2013 Page iv Copyright 2013 by
28、 National Electrical Manufacturers Association AB 3-2013 Page 1 Copyright 2013 by National Electrical Manufacturers Association Section 1 GENERAL 1.1 SCOPE This application guide covers molded case circuit breakers and molded case switches, single-pole and multi-pole, fused and unfused, as well as a
29、ccessories used with them. These circuit breakers and switches are assembled as integral units in supporting housings of insulating material and have rated voltages up to and including 1000 V, 50/60Hz, AC or AC/DC, and have rated interrupting current ratings of 5000 amperes or more. Note: Consult th
30、e manufacturer for dc-only or 400 Hz circuit breakers. This application guide addresses electrical systems with nominal ratings of 600 volts and below ac and dc, which represent the preponderance of the general use application. Wherever the term circuit breaker or breaker is used in this publication
31、, it is understood to mean molded case circuit breaker. Wherever the term switch is used in this publication, it is understood to mean molded case switch. Wherever the abbreviation UL appears, it shall be understood to mean Underwriters Laboratories, Inc. Wherever the abbreviation NEC or “Code” appe
32、ar, they shall be understood to mean the National Electrical Code. “NEC” and “National Electrical Code” are registered trademarks of the National Fire Protection Association. With the exception of the definitions, Appendix A, and where mandatory requirements are indicated by such language as “shall,
33、” “must,” and “such,” this document has been classified as Authorized Engineering Information. 1.2 REFERENCES The reader is referred to the following supplementary reference material. Copies are available from the sources indicated. Standards with ANSI designations are also available from: American
34、National Standards Institute 1430 Broadway New York, NY 10018 ANCE Avenida Lazaro Cardenas #869 Colonia Nueva Industrial Vallejo Delegacion Gustavo A. Madero Mexico, D.F. 07700 NMX-J-266-ANCE Productos Electricos Interruptores Automaticos en Caja Moldeada- Especificaciones y Metodos de Prueba (Elect
35、rical Products Molded Case Circuit Breakers Specifications and Test Methods) AB 3-2013 Page 2 Copyright 2013 by National Electrical Manufacturers Association Canadian Standards Association 178 Rexdale Blvd. Etobicoke, Ontario, Canada M9WlR3 CSA C22.2 No. 5 Molded-Case Circuit Breakers, Molded Case S
36、witches, and Circuit-Breaker Enclosures lnstitute of Electrical and Electronics Engineers, Inc. Publication Sales Department 445 Hoes Lane Piscataway, NJ 08854 ANSI/IEEE Std. 141 IEEE Recommended Practice for Electric Power Distribution for Industrial Plants (IEEE Red Book) ANSI/IEEE Std. 241 IEEE R
37、ecommended Practice for Electric Power Systems in Commercial Buildings (IEEE Gray Book) ANSI/IEEE Std. 242 IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems (IEEE Buff Book) ANSI/IEEE Std. 446 IEEE Recommended Practice for Emergency and Standby Powe
38、r Systems for Industrial and Commercial Applications (IEEE Orange Book) ANSI/IEEE Std. 649 Qualifying Class 1E Motor Control Centers for Nuclear Power Generating Stations-not found on IEEE web site ANSI/IEEE Std. 650 IEEE Standard for Qualification of Class 1E Static Battery Chargers and Inverters f
39、or Nuclear Power Generating Stations IEEE Std. 1015 Recommended Practice for Applying Low Voltage Circuit Breakers Used in Industrial and Commercial Power Systems (IEEE Blue Book) IEEE Std. 323 Qualifying Class 1E Equipment for Nuclear Power Generating Stations not found on IEEE web site IEEE Std. 4
40、93 Recommended Practice for the Design of Reliable Industrial and Commercial Power Systems (IEEE Gold Book) IEEE Std. 602 Recommended Practice for Electric Systems in Health Care Facilities (IEEE White Book) National Electrical Manufacturers Association 1300 North 17th Street Rosslyn, VA 22209 ANSI/
41、NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum) NEMA PB 2.2 Application Guide for Ground Fault Protective Devices for Equipment NEMA AB 4 Guidelines for Inspection and Preventative Maintenance for Molded Case Circuit Breakers Used in Commercial and Industrial Applications NEMA ABP
42、1 Selective Coordination National Fire Protection Association Batterymarch Park Quincy, MA 02269 ANSl/NFPA 20 Centrifugal Fire Pumps ANSI/NFPA 302 Fire Protection Standard for Pleasure and Commercial Motor Craft ANSl/NFPA 70 National Electrical Code ANSI/NFPA 70B Recommended Practice for Electrical
43、Equipment Maintenance ANSI/NFPA 70E Electrical Safety Requirements for Employee Work Places AB 3-2013 Page 3 Copyright 2013 by National Electrical Manufacturers Association Underwriters Laboratories, Inc. 333 Pfingsten Road Northbrook, IL 60062 UL1053 Ground Fault Sensing and Relaying Equipment UL 1
44、699 Arc-Fault Circuit-Interrupters UL 489 (NEMA AB 1) Molded-Case Circuit Breakers, Molded Case Switches, and Circuit-Breaker Enclosures UL 489A Circuit Breakers for Use in Communications Equipment UL 489B Outline of Investigation for Molded Case Circuit Breakers, Molded Case Switches and Circuit Br
45、eaker Enclosures for Use on PV Systems UL 943 Ground Fault Circuit Interrupters U.S. Government Superintendent of Documents Washington, DC 20402 WC 375-GEN Federal Specification-Circuit Breakers, Molded Case: Branch Circuit and Service 1.3 DEFINITIONS accessories: Device that performs a secondary or
46、 minor duty as an adjunct or refinement to the primary or major duty of a molded case product. (accessory) high-fault protector: A self-contained unit housing fuses or high-fault protectors. It is constructed for use with specific molded case products and to be connected directly to the load termina
47、ls of the molded case product. adjustable circuit breaker: A circuit breaker that has adjustable time/current tripping characteristics. These may include 1) inverse-time (i.e., continuous current, long time, and/or short time), 2) instantaneous, and 3) ground-fault characteristics. adjustable instan
48、taneous release (trip): That part of an overcurrent trip element that can be adjusted to trip a circuit breaker instantaneously at various values of current within a predetermined range of currents. alarm switch: A switch that operates to open or close a circuit upon the automatic opening of the mol
49、ded case product with which it is associated. ambient-compensated circuit breaker: A circuit breaker in which means are provided for partially or completely neutralizing the effect of ambient temperature upon the tripping characteristics. ambient temperature: The temperature of the surrounding medium that comes in contact with the circuit breaker or switch. For an enclosed device, it is the temperature of the medium outside the enclosure. arc-fault circuit-interrupter (AFCI): A device intended to mitigate the effects of arcing faults by functioning to de-en
