NEMA MG 2-2014 Safety Standard for Construction and Guide for Selection Installation and Use of Electric Motors and Generators.pdf

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1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA MG 2-2014Safety Standard for Construction and Guide for Selection, Installation and Use of Electric Motors and GeneratorsNEMA MG 2-2014 Safety Standard and Guide for Selection, Installation, and Use of Electric Motors and Ge

2、nerators Published by National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2014 National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the Universal Copyright Convention, th

3、e Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. NOTICE AND DISCLAIMER The information in this publication was considered technically sound by a consensus among persons engaged in its development at the time it was ap

4、proved. Consensus does not necessarily mean there was unanimous agreement among every person participating in the development process. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document herein is one, are developed through a voluntary

5、 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. Although NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not wr

6、ite the documents, nor does it 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. NEMA disclaims liability for any personal injury, property, or other damages of any nature,

7、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 guaranty or warranty, express or implied, as to the accuracy or completeness of any information published h

8、erein, and disclaims and makes no warranty that the information in this document will fulfill any particular purpose(s) or need(s). NEMA does not undertake to guarantee the performance of any individual manufacturers or sellers products or services by virtue of this standard or guide. In publishing

9、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 any person or entity to someone else. Anyone using this document should rely on his or her own independen

10、t judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstance. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for ad

11、ditional 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, test, or inspect products, designs, or installations for safety or health purposes. Any certification or

12、other statement of compliance with any health- or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. MG 2-2014 Page i 2014 National Electrical Manufacturers Association CONTENTS Section 1 SCOPE 1

13、Section 2 REFERENCED STANDARDS AND DEFINITIONS 2 Section 3 GENERAL . 3 Section 4 ENVIRONMENTAL PROTECTION AND METHODS OF COOLING . 4 4.1 Open Machine (IP00, IC01) . 4 4.1.1 Drip-proof Machine (IP12, IC01) 4 4.1.2 Splash-Proof Machine (IP13, IC01) . 4 4.1.3 Semi-Guarded Machine (IC01) 4 4.1.4 Guarded

14、 Machine (IC01) . 4 4.1.5 Drip-proof Guarded Machine (IC01) 4 4.1.6 Open Independently Ventilated Machine (IC06) 5 4.1.7 Open Pipe-Ventilated Machine 5 4.1.8 Weather-Protected Machine 8 4.2 Totally Enclosed Machine 8 4.2.1 Totally Enclosed Nonventilated Machine (IC410) 8 4.2.2 Totally Enclosed Fan-C

15、ooled Machine 8 4.2.3 Totally Enclosed Fan-Cooled Guarded Machine (IC411) 8 4.2.4 Totally Enclosed Pipe-Ventilated Machine (IP44) 8 4.2.5 Totally Enclosed Water-Cooled Machine (IP54) 8 4.2.6 Water-Proof Machine (IP55) 8 4.2.7 Totally Enclosed Air-to-Water-Cooled Machine (IP54) 9 4.2.8 Totally Enclos

16、ed Air-to-Air-Cooled Machine (IP54) . 9 4.2.9 Totally Enclosed Air-Over Machine (IP54, IC417) . 9 4.2.10 Explosion-Proof Machine* . 9 4.2.11 Dust-Ignition-Proof Machine* . 9 Section 5 CONSTRUCTION AND TESTS 10 5.1 General 10 5.2 Corrosion Protection 10 5.3 High Potential Testing 10 5.3.1 Motors 10 5

17、.3.2 Synchronous Generators . 11 5.3.3 Grounding 11 5.3.4 Accessories and Components . 12 5.3.5 Discharging Windings After Test . 12 5.3.6 Guarding 12 5.4 Thermal Protection 12 5.5 Impedance Protection 12 5.6 Overspeed . 12 5.6.1 Induction Motors 13 5.6.2 Direct-Current Motors 13 5.6.3 Alternating-C

18、urrent Series and Universal Motors 15 5.6.4 Synchronous Motors 15 5.6.5 Synchronous Generators . 15 5.6.6 Direct-Current Generators . 15 Section 6 SAFETY IN MACHINE APPLICATION . 16 6.1 Matching of the Machine to the Load . 16 6.2 Degree of Machine Enclosure . 16 6.2.1 General 16 6.2.2 Application i

19、n Residences and in Places Regularly Open to the Public 16 6.2.3 Applications in Places Restricted to Persons Employed on the Premises 17 MG 2-2014 Page ii 2014 National Electrical Manufacturers Association 6.2.4 Application in Places Accessible Only to Qualified Personnel . 17 6.2.5 AC Motors For C

20、lass I, Division 2, Hazardous Locations 23 6.3 Proper Selection of Machines 24 6.3.1 Variation From Rated Voltage and Rated Frequency 24 6.3.2 Usual Service Conditions . 33 6.3.3 Unusual Service Conditions . 33 6.3.4 Speed Limitation 34 6.3.5 Operation of Direct-current Motors on Rectified Alternati

21、ng Current . 35 6.3.6 Shaft Loading . 36 6.3.7 Transient Torques . 36 6.3.8 Torsional Vibration . 36 6.3.9 Torque Pulsations During Starting of Synchronous Motors . 37 Section 7 SAFETY IN MACHINE INSTALLATIONS . 38 7.1 Installation and Protection . 38 7.2 Grounding 38 7.3 Wiring Connections . 38 7.4

22、 Flammable Materials . 38 7.5 Rotating Parts 39 7.6 Maximum Speed of Drive Components . 39 7.7 Lifting of Machines . 39 7.8 Surface Temperatures . 41 7.9 Hold-down Bolt Sizes . 41 7.10 Power Factor Correction 41 7.11 Starting Current in Induction Motors 43 7.11.1 Locked Rotor Current 43 7.11.2 Insta

23、ntaneous Peak Value of Inrush Current . 43 Section 8 SAFETY IN MACHINE USE 46 8.1 Loading 46 8.2 Automatic Reset Thermal Protectors. 46 8.3 Maintenance 46 8.4 Repair 47 Tables 1 HIGH-POTENTIAL TEST VOLTAGESFOR UNIVERSAL, INDUCTION, AND DIRECT- CURRENT MOTORS 13 2 INDEX OF PROTECTION (IP) 17 3 TYPICA

24、L CHARACTERISTICS AND APPLICATIONS OF FIXED FREQUENCY MEDIUM AC SQUIRREL-CAGE INDUCTION MOTORS . 21 4 MAXIMUM LOCKED ROTOR CURRENT FOR 60-HZ INDUCTION MOTORS AT 230 VOLTS 34 5 LOCKED ROTOR kVA/Hp . 35 Figures 1 PROBE FOR HAZARDOUS ROTATING PARTS . 5 2 PROBE FOR FILM-COATED WIRE . 5 3 ARTICULATE PROB

25、E FOR UNINSULATED LIVE METAL PARTS . 6 4 GENERAL SHAPE OF SPEED-TORQUE CURVES FOR MOTORS WITH NEMA DESIGN A, B, C, AND D IEC DESIGN H AND N . 22 5 SINGLE LIFTING DEVICE (TYPICAL) 30 6 MULTIPLE LIFTING DEVICE (TYPICAL) . 30 7 SINGLE LIFTING DEVICE (TYPICAL) 32 8 MULTIPLE LIFTING DEVICES (TYPICAL) VER

26、TICAL MACHINE . 32 9 MULTIPLE LIFTING DEVICE (TYPICAL) HORIZONTAL MACHINE 32 MG 2-2014 Page iii 2014 National Electrical Manufacturers Association Foreword The use of electric machines, like that of all other utilization of concentrated power is potentially hazardous. The degree of hazard can be gre

27、atly reduced by proper design, selection, installation and use, but hazards cannot be completely eliminated. The reduction of hazard is the joint responsibility of the user, the manufacturer of the driven or driving equipment, and the manufacturer of the machine. The words “driven or driving equipme

28、nt“ as used in this publication mean equipment driven by a motor or equipment driving a generator. This publication is intended to assist the user and the manufacturer of the driven or driving equipment in the selection of machines that have been designed and built to have features that contribute t

29、o safety. The machine manufacturer has little, if any control over the selection, installation, and use of these machines. Since the reduction of hazards depends greatly on how machines are selected, installed, and used, this publication has been prepared as a guide to assist the user and the manufa

30、cturer of the driven or driving equipment in the proper selection, installation, and use of machines. It points out possible hazards and suggests ways and means to reduce them. If the guidelines are followed, the possible hazards and risks of using machines will be reduced. MG 2-2014 revises and sup

31、ersedes MG 2-2001, Rev. 1-2007. This publication is periodically reviewed by the Motor and Generator Section of NEMA for any revisions necessary to keep it up to date with advancing technology. Proposed or recommended revisions should be submitted to: Senior Technical Director, Operations National E

32、lectrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 MG 2-2014 Page iv 2014 National Electrical Manufacturers Association MG 2-2014 Page 1 2014 National Electrical Manufacturers Association Section 1 SCOPE This publication provides recommendations for the sel

33、ection, installation, and use of rotating electric machines in such a manner as to provide for the practical safeguarding of persons and property. Excluded from the scope of this publication are the following: a) Welding generators. b) Booster, dynamic braking, and absorption type machines. c) Isola

34、ted electric farm lighting plants. d) Variable speed generator equipment for railway passenger cars. e) Main propulsion motors, generators, and motor generator sets mounted on railroad and transit locomotives and cars. f) Automotive motors, generators, and motor generator sets. g) Motors, generators

35、, exciters, and motor generator or exciter sets mounted on airborne craft. h) Toy motors and small synchronous motors of the type generally used in household clocks and timing devices. i) Additional specific features required in machines for use in hazardous (classified) locations. Such locations mi

36、ght be in mines or in areas defined in the National Electrical Code (ANSI/NFPA 70), Articles 500 through 503. j) Machines built to military specifications having requirements which conflict with or override the provisions of this publication. k) Machine parts intended for installation in a hermetica

37、lly sealed enclosure. l) Non-salient-pole generators and their exciters. m) Generators larger than 10,000 kVA, and their exciters, for hydraulic turbine drive, including reversible motor generator units. n) Synchronous condensers, frequency changers, and phase converters. Since any machine can be in

38、stalled or operated in such a manner that hazards can occur, compliance with this publication does not by itself assure a safe installation. However, when a machine complying with this publication is properly selected with respect to the driven load and environment, and is installed in accordance wi

39、th the applicable provisions of national codes and sound local practices, the hazards to persons and property will be reduced. MG 2-2014 Page 2 2014 National Electrical Manufacturers Association Section 2 REFERENCED STANDARDS AND DEFINITIONS In this publication, reference is made to the following st

40、andards and other publications listed below. Copies are available from the indicated sources: American National Standards Institute (ANSI) 11 West 42nd Street New York, NY 10036 ANSI/ASME B15.1-2000 Safety Standard for Mechanical Power Transmission Apparatus American Society for Testing and Material

41、s (ASTM) 1916 Race Street Philadelphia, PA 19103 ASTM D149-81 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies International Electrotechnical Commission (IEC)* 3 Rue de Varemb, CP 131, CH-1211 Geneva 20, Swi

42、tzerland IEC 60034 (Series) Rotating Electrical Machines National Electrical Manufacturers Association (NEMA) 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 NEMA MG 1- 2011 Motors and Generators NEMA MG 10-2001 (R2007) Energy Management Guide for Selection and Use of Polyphase Motors NEMA Appli

43、cation Guide for AC Adjustable Speed Drive Systems National Fire Protection Association (NFPA) 1 Batterymarch Park Quincy, MA 02269 ANSI/NFPA 70-2002 National Electrical Code Underwriters Laboratories, Inc. (UL) 333 Pfingsten Road Northbrook, IL 60062 ANSI/UL 674-1994 Electric Motors and Generators

44、for Use in Hazardous Locations, Class I Groups C and D; Class II Groups E, F, and G *Also available from ANSI MG 2-2014 Page 3 2014 National Electrical Manufacturers Association Section 3 GENERAL Construction of rotating machines alone cannot assure safety in use. There is as great a need for safegu

45、ards in the selection, installation, and use of machines as there is for safeguards in their design and manufacture. The following recommendations are generally applicable but there may be situations where conflict with other safety measures or operational requirements will necessitate that these re

46、commendations be modified. Where the above-mentioned safeguards and past experience of the user are not sufficient to serve as a guide, the manufacturer of the driven or driving equipment or the machine manufacturer, or both, should be consulted to develop further information. This further informati

47、on should be considered by the user, his consultants, or others most familiar with the details of the application involved when making the final decision. The importance of communication between manufacturer and user cannot be over-emphasized. The chances for preventing hazardous incidents and limit

48、ing their consequences are greatly improved when both user and manufacturer are correctly and fully informed with respect to the intended use and all environmental and operating conditions. Since such intended use and environmental and operating conditions are under the sole control of the user, who

49、 has the most complete knowledge of the intended use and the environmental and operating conditions, the user should select and install machines which will optimize safety in use. This guide is intended to assist the user in selection, installation, and use of electric machines. MG 2-2014 Page 4 2014 National Electrical Manufacturers Association Section 4 ENVIRONMENTAL PROTECTION AND METHODS OF COOLING Ventilation and other design considerations of machines frequently require openings in the exterior enclosures in the vicinity of uninsulated live metal parts, space he