1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA Condensed MG 1-2011Information Guide for General PurposeIndustrial AC Small andMedium Squirrel-Cage Induction Motor StandardsNEMA Condensed MG 1-2011 Information Guide for General Purpose Industrial AC Small and Medium Squir
2、rel-Cage Induction Motor Standards 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 Universa
3、l Copyright Convention, the 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 develop
4、ment at the time it was approved. 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 dev
5、eloped through a voluntary 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
6、 consensus, it does not write 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 oth
7、er damages of any nature, 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 a
8、ny information published herein, 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 standar
9、d 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 any person or entity to someone else. Anyone using this document should rely on
10、 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 circumstance. Information and other standards on the topic covered by this publication may be available from other sources, which the user
11、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, test, or inspect products, designs, or installations for safety or health purpo
12、ses. Any certification or 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. Condensed MG 1-2011 Page i 2014 National Electrical Manufacturers Ass
13、ociation CONTENTS Page Foreword. iv 1 PURPOSE 2 2 SCOPE . 2 3 DEFINITIONS . 2 4 CLASSIFICATION OF DEGREES OF PROTECTION PROVIDED FOR ENCLOSURES FOR ROTATING MOTORS 4 4.1 Single Characteristic Numeral . 4 4.2 Supplementary Letters 4 4.3 Letters Following Numerals . 4 4.4 Letters Placed Immediately Af
14、ter the Letters IP 4 4.5 Degrees of ProtectionFirst Characteristic Numeral . 4 4.6 Degrees of ProtectionSecond Characteristic Numeral 5 5 METHODS OF COOLING . 5 5.1 Arrangement of the IC Code . 5 6 MECHANICAL VIBRATION MEASUREMENT, EVALUATION, AND LIMITS OF AC MEDIUM MOTORS 5 7 SMALL (FRACTIONAL) AN
15、D MEDIUM (INTEGRAL) MOTORS RATINGS 5 7.1 Voltages . 5 7.2 Frequencies . 6 7.3 Horsepower and Speed Ratings 6 7.3.1 Small Induction Motors . 6 7.3.2 Single-Phase Medium Motors 6 7.3.3 Polyphase Medium Induction Motors . 6 7.3.4 Basis of Single-Phase Horsepower Rating 6 7.4 Horsepower Ratings of Multi
16、speed Motors . 6 7.4.1 Constant Horsepower . 6 7.4.2 Constant Torque . 6 7.4.3 Variable Torque 6 7.5 Rating of 60-Hertz Motors Operated on 50-Hertz Power 6 7.6 Time Ratings for Single-Phase and Polyphase Induction Motors . 6 7.7 Code Letters (for Locked-Rotor kVA)Nameplate Marking . 7 7.8 Nameplate
17、Temperature Ratings for Alternating-Current Small Motors . 7 7.9 Nameplate Marking for Small Single-Phase and Polyphase Motors . 7 7.9.1 Dual Voltage, Dual Frequency, and Dual Speed Motors 7 7.10 Nameplate Marking for Medium Single-Phase and Polyphase Induction Motors . 8 7.11 Additional Nameplate I
18、nformation for All Motors . 8 8 DIMENSIONS AC SMALL (FRACTIONAL) AND MEDIUM (INTEGRAL) MOTORS . 9 8.1 System for Designating Frames 9 8.1.1 Small Motors 9 8.1.2 Medium Motors . 9 8.2 Frame Assignments 10 8.3 Lettering of Dimension Sheets 10 8.4 Tolerances for Shaft Runout . 10 Condensed MG 1-2011 Pa
19、ge ii 2014 National Electrical Manufacturers Association 8.5 Grounding Means for Field Wiring 10 9 TESTS AND PERFORMANCE AC SMALL AND MEDIUM MOTORS 10 9.1 Routine Tests for Polyphase Medium Induction Motors 10 9.2 High-Potential Test Voltages for Induction Motors MG 1-12.3 10 9.3 Test Methods . 11 9
20、.4 Performance Characteristics . 11 9.5 Torque Characteristics of Single-Phase General-Purpose Induction Motors 11 9.5.1 Breakdown Torque of Single-Phase Motors. 11 9.5.2 Locked-Rotor Torque of Single-Phase Small Motors . 11 9.5.3 Locked-Rotor Torque of Single-Phase Medium Motors . 11 9.5.4 Pull-Up
21、Torque of Single-Phase Medium Motors . 11 9.6 Locked-Rotor Current Characteristics of Single-Phase and Polyphase General-Purpose Induction Motors 11 9.6.1 Locked-Rotor Current of Single-Phase Small Motors, Designs N, O,and General Purpose. . 11 9.6.2 Locked-Rotor Current of Single-Phase Medium Motor
22、s, Designs L and M . 11 9.6.3 Locked-Rotor Current of 3-Phase 60-Hertz Small and Medium Squirrel-Cage Induction Motors Rated at 230 Volts . 12 9.7 Torque Characteristics of Polyphase General-Purpose Induction Motors 12 9.7.1 Breakdown Torque Characteristics of Polyphase Small Motors 12 9.7.2 Locked-
23、Rotor Torque of Single-Speed Polyphase Squirrel-Cage Medium Motors with Continuous Rating . 12 9.7.3 Breakdown Torque of Single-Speed Polyphase Squirrel-Cage Medium Motors with Continuous Ratings . 12 9.7.4 Pull-Up Torque of Single-Speed Polyphase Squirrel-Cage Medium Motors with Continuous Ratings
24、12 9.8 Temperature Rise for Small and Medium Single-Phase and Polyphase Induction Motors 12 9.9 Variations from Rated Voltage and Rated Frequency . 13 9.9.1 Running 13 9.9.2 Starting . 13 9.10 Voltage Unbalance 13 9.11 Variation from Rated Speed 13 9.12 Variation from Nameplate AmperesAlternating-Cu
25、rrent Medium Motors 13 9.13 Occasional Excess Current . 13 9.14 Stall Time 14 9.15 Service Factor of Alternating-Current Motors 14 9.15.1 General-Purpose Alternating-Current Motors of the Open Type 14 9.16 Overspeeds for Squirrel-Cage Motors . 14 9.16.1 General Purpose Squirrel-Cage Induction Motors
26、 . 14 9.16.2 General-Purpose Design A and B Direct-Coupled Squirrel-Cage Induction Motors 14 9.17 Machine Sound (Medium Induction Motors) 15 9.17.1 General 15 9.17.2 Sound Measurement 15 9.17.3 Sound Power Levels of Polyphase Squirrel-Cage Induction Motors at No Load . 15 9.17.4 Sound Power Levels o
27、f Polyphase Squirrel-Cage Induction Motors at Rated Load 15 Condensed MG 1-2011 Page iii 2014 National Electrical Manufacturers Association 9.18 Number of Starts . 15 9.19 Thermal Protection of Medium Motors 16 9.19.1 Winding Temperature . 16 9.20 Overtemperature Protection of Medium Motors Not Meet
28、ing the Definition of “Thermally Protected” 16 9.20.1 Type 1Winding Running and Locked Rotor Overtemperature Protection 16 9.20.2 Type 2Winding Running Overtemperature Protection 17 9.20.3 Type 3Winding Overtemperature Protection, Nonspecific Type . 17 9.21 Efficiency . 17 9.21.1 Determination of Mo
29、tor Efficiency and Losses . 17 9.21.2 Efficiency of Polyphase Squirrel-Cage Medium Motors with Continuous Ratings 18 9.21.3 Efficiency Levels of Energy Efficient Polyphase Squirrel-Cage Induction Motors 18 9.21.4 Efficiency Levels of Premium Efficiency Electric Motors 18 9.21.5 Effects of Load on Mo
30、tor Efficiency 18 10 APPLICATION DATA AC SMALL AND MEDIUM MOTORS . 19 10.1 Service Conditions . 19 11 APPLICATION CONSIDERATIONS FOR CONSTANT SPEED DESIGN A AND B INDUCTION MOTORS USED ON A SINUSOIDAL BUS WITH HARMONIC CONTENT . 19 11.1 Efficiency . 19 11.2 Derating for Harmonic Content 19 11.2.1 Ha
31、rmonic Voltage Factor (HVF) Defined . 19 11.3 Power Factor Correction . 20 12 APPLICATION CONSIDERATIONS FOR GENERAL PURPOSE DESIGN a AND b INDUCTION MOTORS USED WITH ADJUSTABLE-VOLTAGE OR ADJUSTABLE-FREQUENCY CONTROLS OR BOTH 20 12.1 Torque . 20 12.1.1 Motor Torque During Operation Below Base Speed
32、 20 12.1.2 Torque Derating at Reduced Speeds . 20 12.1.3 Motor Torque During Operation Above Base Speed 20 12.2 Current. 21 12.2.1 Running Current . 21 12.2.2 Starting Current 21 12.3 Efficiency . 21 12.4 Maximum Safe Operating Speeds 21 12.5 Sound 21 12.6 Resonances, Sound, Vibration 22 12.7 Voltag
33、e Stress . 22 12.8 Power Factor Correction . 22 12.9 Operation in Hazardous (Classified) Locations . 22 Condensed MG 1-2011 Page 1 2014 National Electrical Manufacturers Association Foreword In the preparation of this publication, input of users and other interested parties has been sought and evalu
34、ated. Inquiries, comments, and proposed or recommended revisions should be submitted to the concerned NEMA product Subdivision by contacting the: Senior Technical Director, Operations National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 This publication w
35、as developed by the Motors and Generators Section. Section approval of the document does not necessarily imply that all section members voted for its approval or participated in its development. At the time it was approved, the section was composed of the following members: A.O. Smith Electrical Pro
36、ducts CompanyTipp City, OH Baldor Electric CompanyFort Smith, AR Brook Crompton North AmericaToronto, Canada Cummins, IncorporatedMinneapolis, MN Emerson Electric CompanySt. Louis, MO GE Industrial SystemsFort Wayne, IN Howell Electric MotorsPlainfield, NJ Peerless-Winsmith, IncorporatedWarren, OH R
37、AM IndustriesLeesport, PA Regal-Beloit CorporationBeloit, WI Leeson ElectricGrafton, WI Lincoln ElectricCleveland, OH Marathon ElectricWausau, WI SEW-Eurodrive, IncorporatedLyman, SC Siemens Energy permanent-split capacitor which has the same capacitance for both starting and running; two-value capa
38、citor motor in which there are different values of effective capacitance for starting and running. MG 1-1.20.3.3 current: locked-rotor current: The steady-state current taken from the line, with the rotor locked and with rated voltage and rated frequency applied to the motor. MG 1-1.53 no-load curre
39、nt: The current flowing through a line terminal of a winding when rated voltage is applied at a rated frequency with no connected load. MG 1-1.54 design letters: Identifies specific performance requirements for starting and operating characteristics. See Table 8. MG 1-1.19.1 dimensions: Dimension ar
40、e indicated by the NEMA letters given in Table 19. MG 1-4.1 dripproof motor: An open motor in which the ventilating openings are so constructed that successful operation is not interfered with when drops of liquid or solid particles strike or enter the enclosure at any angle from 0 to 15 degrees dow
41、nward from the vertical. MG 1-1.25.1 dripproof guarded motor: A dripproof motor whose ventilating openings are guarded. MG 1-1.25.5 energy efficient polyphase squirrel-cage induction motor: An induction motor having an efficiency in accordance with 9.21.3. MG 1-1.41.2 frame number: The frame number
42、for small motors is the “D“ dimension in inches multiplied by 16. The frame number for medium motors consists of three or four digits. The first two digits are equal to four times the “D“ dimension in inches. When this product is not a whole number, the first two digits of the frame number are the n
43、ext higher whole number. The third and, when required, fourth digit of the frame number is obtained from the value of the “2F“ dimension in inches as shown in the columns headed 1 to 15, inclusive, in the Table 13. MG 1-4.2 general-purpose motor: A squirrel-cage induction motor, rated 500 horsepower
44、 and less, open or enclosed construction. It is designed in standard ratings with standard operating characteristics and mechanical construction for use under usual service conditions without restriction to a particular application or type of application. MG 1-1.6 guarded motor: An open motor in whi
45、ch all openings giving direct access to live metal or rotating parts (except smooth rotating surfaces) are limited in size by the structural parts or by screens, baffles, grilles, expanded metal, or other means to prevent accidental contact with hazardous parts. Openings giving direct access to such
46、 live or rotating parts shall not permit the passage of a cylindrical rod 0.75 inch in diameter. The openings in the motor enclosure shall be such that (1) a probe such as that illustrated in Figure 1, when inserted through the openings, will not touch an uninsulated live metal part or a hazardous r
47、otating part and Condensed MG 1-2011 Page 3 2014 National Electrical Manufacturers Association (2) a probe such as that illustrated in Figure 1, when inserted through the openings, will not touch film coated wire. MG 1-1.25.4 high-potential tests: High-potential tests are tests which consist of the
48、application of a voltage higher than the rated voltage for a specified time for the purpose of determining the adequacy against breakdown of insulating materials and spacings under normal conditions. MG 1 Part 3 IC code: Acronym for “International Cooling.” See Clause 5, Methods of Cooling. MG 1 Par
49、t 6 IP code: Acronym for “International Protection.“ See Clause 4, Classification of Degrees of Protection. MG 1 Part 5 medium (integral) motor: An alternating-current medium motor is (1) built in a three-or four-digit frame series (or equivalent for motors without feet); and (2) having a continuous rating up to and including the information in Table 2. MG 1-1.4.1 Premiumefficiency electric motor: A continuous rated, single-speed, polyphase, squirrel-cage induction motor of 2, 4, or 6 pole design meeting the performance r
