UL 2111 CRD-2009 UL Standard for Safety Overheating Protection for Motors - Section Paragraph Reference 7 8 9 14 15 16 Subject Power Interruption During Locked Rotor Tests on Impe.pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared and published by Underwriters Laboratories Inc.(UL). It is normative for the a

2、pplicable UL Product Certification Program(s); however, it is currently notpart of the UL Standard(s) referenced below.Product Category (CCN): XEWR, XEIT, XDNW, XDAMStandard Number: UL 2111Edition Date: March 14, 2002Edition Number: 1Section / Paragraph Reference: 7, 8, 9, 14, 15, 16Subject: Power I

3、nterruption During Locked Rotor Tests on Impedance ProtectedMotors and Motors Containing Automatic Reset Thermal Motor Protectors (TMP)DECISION:New41B.1.1.1 If the Locked Rotor Endurance Test is interrupted prior to its completion (15 days), themanufacturer is to be given the option of restarting th

4、e test from the beginning with a new sample orcontinuing the test, with the original motor, at the point where it was interrupted, until the cumulative 15days has elapsed. If the test is restarted and the motor complies with the acceptance criteria specified in41B.2 41B.4, then the results are consi

5、dered acceptable. If the motor fails to meet one or more of thecriteria, then, at the manufacturers discretion, the test may be repeated with a new sample.41B.5.1 Starting at room temperature, a motor provided with a self-holding protector is to be energized inthe locked rotor condition. The self-ho

6、lding protector shall open the circuit. Once the self-holding protectoropens the circuit, and while still energized, the assembly is to be placed inside a freezer maintained at0C for 24 8 hours.41B.5.2 During the 24 8 hours, the self-holding protector shall not reset.RATIONALE FOR DECISION:Long-term

7、 tests may potentially be interrupted for various reasons. If that occurs, a decision must bemade to determine whether the test may be continued following interruption or be restarted from thebeginning, potentially with new samples. Continuing the test is an acceptable approach.The Locked Rotor Test

8、 is a combination of two tests: Locked Rotor Temperature Test (LRTT) 72 Hours and Locked Rotor Endurance Test (LRET) 15 daysLRET is a time and temperature stress on the insulating materials, a stress test on the movable parts ofthe automatic reset protector and a test of the freedom from welding of

9、the contacts of the automatic resetprotector. In each case, the effects are cumulative.Interrupting the LRET represents a somewhat more severe test situation for the following reasons:UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL1. The mass

10、 of the motor is allowed to cool, all of the materials and components contract and when thetest is restarted, the materials and components again expand. The cumulative effects of the time andtemperature on the materials are the same but now the added stress of the slight shifting and abrasionthat oc

11、curs due to the additional cooling/heating cycle has been introduced.2. In the early stages of the test for a motor employing an automatic reset protector, there is some degreeof overshoot before the temperature is stabilized and then a steadily decaying cycle of temperatureexcursions as the “system

12、” stabilizes. By restarting, this period of overshoot is experienced twice.3. When a motor with its rotor locked is first energized, there is an initial “cold coil inrush” current thatoccurs. Again, by restarting, this stress is experienced twice.Copyright 2009 Underwriters Laboratories Inc.UL, in p

13、erforming its functions in accordance with its objectives, does not guarantee or warrant thecorrectness of Certification Requirement Decisions it may issue or that they will be recognized or adoptedby anyone. Certification Requirement Decisions are the opinion of Underwriters Laboratories Inc. inpra

14、ctically applying the requirements of the standard. They do not represent formal interpretations of thestandard under American National Standards Institute (ANSI) processes. UL shall not be responsible toanyone for the use of or reliance upon Certification Requirement Decisions by anyone. UL shall n

15、ot incurany obligation or liability for damages, including consequential damages, arising out of or in connectionwith the use or reliance upon Certification Requirement Decisions. The electronic version of theCertification Requirement Decision is the current version and previously printed copies may be outdated.This document is published as a service to ULs certification customersSTANDARD NUMBER: UL 2111 -2-