1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA MG 1-2016 Supplement Motors and Generators Section IV Part 34: Air-Over Motor Efficiency Test MethodNEMA MG 1-2016 Air-Over Motor Efficiency Test Method Section IV Part 34Page 1 2016 National Electrical Manufacturers Associa
2、tion NEMA Standards Publication MG 1-2016 Motors and Generators Section IV Part 34: Air-Over Motor Efficiency Test Method Published by National Electrical Manufacturers Association 1300 North 17thStreet, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2016 National Electrical Manufacturers Associatio
3、n. All rights, including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. NEMA MG 1-2016 Air-Over Motor Efficiency Test Method Sec
4、tion IV Part 34Page 2 2016 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Consensus does not nec
5、essarily mean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consen
6、sus 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 and establishes rules to promote fairness in the development of consensus, it does not wr
7、ite 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. NEMA disclaims liability for any personal injury, property, or other damages of any nature
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9、ion 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 individual manufacturer or sellers products or services by virtue of this standard or gui
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11、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 covered by this publication may be available from other sources, which the user may wis
12、h 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 purposes. An
13、y 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. NEMA MG 1-2016 Air-Over Motor Efficiency Test Method Section IV Part 34Page 1
14、 2016 National Electrical Manufacturers Association Section IV Performance Standards Applying to All Machines Part 34 Air-Over Motor Efficiency Test Method 34.0 Scope An air-over (AO) motor with a totally enclosed or open enclosure is defined as an electric motor rated to operate in and be cooled by
15、 the airstream of a fan or blower that is not supplied with the motor, and whose primary purpose is providing airflow to an application, rather than the primary purpose of cooling the motor. The cooling is external and therefore removed when the motor is connected to a dynamometer. This type of moto
16、r requires a special procedure to reach an appropriate temperature. These procedures replace the temperature test portion of the applicable efficiency test method. The user is then directed to conduct the load test per the applicable efficiency test method. 34.1 Applicable Motor Efficiency Test Meth
17、ods IEEE 112 IEEE 114 CSA C390 CSA C747 IEC 60034-2-1 34.2 AO Temperature Test Procedures The following three AO temperature test procedures are deemed equivalent and can be used interchangeably. Details for these procedures appear in Parts 34.3 through 34.5. 34.2.1 AO Temperature Test Procedure 1St
18、abilized Temperature with Air Velocity Measurement This temperature test procedure shall be conducted to thermally stabilize the AO motor at the rated load conditions using the customer or application specific air velocity rating in feet per minute or meters per second for cooling. The temperature s
19、hall remain within 10C of this stabilized temperature when the subsequent load test portion of the applicable efficiency test method begins. 34.2.2 AO Temperature Test Procedure 2Target Temperature with Air Flow This temperature test procedure shall be conducted to bring the AO motor at the rated lo
20、ad conditions to within 10C of the target temperature using external cooling air. The temperature shall remain within 10C of the target temperature when the subsequent load test portion of the applicable efficiency test method begins. 34.2.3 AO Temperature Test Procedure 3Target Temperature without
21、Air Flow This temperature test procedure shall be conducted to bring the AO motor at the no load or reduced load condition to within 10C of the target temperature without using external cooling air. The temperature shall remain within 10C of the target temperature when the subsequent load test porti
22、on of the applicable efficiency test method begins. NEMA MG 1-2016 Air-Over Motor Efficiency Test Method Section IV Part 34Page 2 2016 National Electrical Manufacturers Association 34.3 AO Temperature Test Procedure 1Stabilized Temperature with Air Velocity Measurement 1. If temperature detectors ar
23、e not already installed on the winding, then install them in accordance with the applicable efficiency test standard. If it is permissible to disassemble the motor, then the preferred location for the temperature detector(s) is on the winding end coils.1If it is not permissible to disassemble the mo
24、tor, then install the temperature detector(s) on the stator iron (i.e., where the terminal box is located). 2. Perform the temperature test in the following manner: a. Run the motor at rated load with air flow provided by an external blower. b. Adjust the external blower in order to increase or decr
25、ease air flow over the motor so that rated air velocity can be achieved. c. Rated air velocity is achieved as follows: 1) Air velocity shall be the average of three measurements on the motors frame nearest the mid-point of the stator winding core. If the stator core position is unknown, then use the
26、 mid-point of the frame. It is recommended to be taken at 3, 9, and 12 oclock positions unless one or more of those positions is obstructed by a terminal box or other protruding accessory. 2) The air velocity shall be measured within 1 inch from the surface of the motors frame (for finned motors the
27、 measurement location shall be at no greater distance than at the tip of the fin). 3) Minimum required air velocity shall be per the manufacturers specifications, and the maximum air velocity shall be no more than 25% greater than the minimum required velocity. d. Monitor all temperature detectors a
28、nd their respective temperatures. 1) If a temperature test has not already been performed on a duplicate motor with temperature detectors in similar locations, then operate the motor at the rated air velocity until the temperature rise change of the highest temperature detector is 1C or less over a
29、30 minute period. Shut the motor and blower down and determine the average winding temperature2in accordance with the average winding temperature resistance method (see IEEE 112-2004 Section 5.8.5.13). Exception: for a single phase motor for which it is not possible to isolate the main winding from
30、the auxiliary winding in order to measure its resistance separately, it is permissible to use the hottest main winding temperature measured by the detector as the average winding temperature. 2) If a temperature test has already been performed on a duplicate motor with temperature detectors in simil
31、ar locations, then operate the motor at the rated air velocity until: 1For single phase motors, this is the end coils of the main winding. 2Throughout this Part 34, unless otherwise specified (for example, by the use of the phrase “by detector”), the terms “average winding temperature,” “temperature
32、 rise,” and “target temperature” are determined by applying the average winding temperature method described in IEEE 112-2004 Section 5.8.5.1, IEEE 114-2010 Section 5.3.2, or CSA C390 Clause 7.2.1. For single-phase motors, this value is for the main winding. 3or IEEE 114-2010 Section 5.3.2 or CSA C3
33、90 Clause 7.2.1 NEMA MG 1-2016 Air-Over Motor Efficiency Test Method Section IV Part 34Page 3 2016 National Electrical Manufacturers Association a) For polyphase motors: the temperature of the hottest detector multiplied by the following ratio is within 10C of the average winding temperature by resi
34、stance from the previous temperature test on a duplicate motor: (average winding temperature by resistance from the previous temperature test on a duplicate motor) / (temperature of the detector in this same location from the previous temperature test on a duplicate motor) b) For single-phase motors
35、 for which the main winding can be isolated from the auxiliary winding in order to measure its resistance separately: the temperature of the hottest detector multiplied by the following ratio is within 10C of the average main winding temperature by resistance from the previous temperature test on a
36、duplicate motor: (average main winding temperature by resistance from the previous temperature test on a duplicate motor) / (temperature of the detector in this same location from the previous temperature test on a duplicate motor) c) For single-phase motors for which the main winding cannot be isol
37、ated from the auxiliary winding in order to measure its resistance alone: the temperature of the hottest detector is within 10C of the hottest detector from the previous temperature test on a duplicate motor. 3. Perform the load test to the applicable efficiency test method (e.g., IEEE 112 method B,
38、 and CSA C390) with the external blower configured exactly as it was at the conclusion of the temperature test. When the load test is begun, the winding temperature must still be within 10C of the stabilized winding temperature from step 2.d. 34.4 AO Temperature Test Procedure 2Target Temperature wi
39、th Air Flow 1. Method for determining target temperature a. If motor temperature rise is not otherwise indicated then: 1) For polyphase motors: select the appropriate target temperature from Table 34-14based on the indicated insulation class. 2) For single-phase motors: the target temperature shall
40、be 75C5b. If motor temperature rise is indicated in terms of an insulation class, then select the target temperature from Table 34-1 that corresponds to the temperature rise being defined in terms of an insulation class, i.e., if indicated insulation class is class “F” and indicated temperature rise
41、 is class “B,” then select 95C target temperature. c. If motor temperature rise is indicated as a numerical value (i.e., 50C) then the target temperature is the sum of that temperature rise (50C) and the reference ambient of 25C (resulting in a target temperature of 75C in this example). 4 This tabl
42、e is equivalent to Table 1 in IEEE 112-2004. 5This is consistent with IEEE 114-2010 Section 8.2.1 and CSA C747 Clause 6.2. NEMA MG 1-2016 Air-Over Motor Efficiency Test Method Section IV Part 34Page 4 2016 National Electrical Manufacturers Association Table 34-1 Target Temperature in C (Determined b
43、y applying the average winding temperature method described in IEEE 112-2004, Section 5.8.5.16including 25C ambient) Insulation Class Target Temperature in C A 75 B 95 F 115 H 130 2. If temperature detectors are not already installed on the winding, then install them in accordance with the applicabl
44、e efficiency test standard. If it is permissible to disassemble the motor, then the preferred location for the temperature detector(s) is on the winding end coils7. If it is not permissible to disassemble the motor, then install the temperature detector(s) on the stator iron (i.e., where the termina
45、l box is located). 3. Perform the temperature test in the following manner: a. Run the motor at rated load with air flow provided by an external blower. b. Monitor the temperature detector(s), and if the highest of the reading(s) cannot get within the following tolerance of the target temperature de
46、fined in step 1, then it is recommended to adjust the external blower in order to increase or decrease the air velocity over the motor: 1) If the temperature detector(s) are located on the winding, then the tolerance is 20C. 2) If the temperature detectors(s) are located on the stator iron, then the
47、 tolerance is 10C /40C. c. When the highest of the temperature detector reading(s) falls within an appropriate tolerance, such as that proposed in step 3.b, of the target temperature, then shut the motor and blower down and determine the average winding temperature in accordance with the average win
48、ding temperature resistance method (See IEEE-112-2004, section 5.8.5.18). Exception: for a single phase motor for which it is not possible to isolate the main winding from the auxiliary winding in order to measure its resistance separately, it is permissible to use the hottest main winding temperatu
49、re measured by the detector as the average winding temperature. d. If the average winding temperature is within 10C of the target temperature defined in step 1, then: 1) Make note of the ratio of (average winding temperature) to (highest of the temperature detector readings). 2) With the external blower configured exactly as it was immediately prior to shutting the motor down in step 3.c, restart the motor and run at rated load until 6or IEEE 114-2010 Section 5.3.2. or CSA C390 Clause 7.2.1 7For single phase motors, this is the end c
