Recommended Practice for Thermal Evaluation of Unsealed or Sealed Insulation Systems for AC Electric Machinery Employing Form- Wound Pre-Insulated Stator Coils for Machines Rated 15 000 V and Below
|Publication Date:||10 December 2008|
This recommended practice outlines test procedures for comparing two or more unsealed or sealed insulation systems in accordance with their expected life at rated temperature. The procedure is limited to insulation systems for AC electrical machines using form-wound pre-insulated stator coils rated 15 000 V and below. The intent of this test procedure is to evaluate unsealed insulation systems for use with air cooling under usual (normal) service conditions, or sealed insulation systems for use under severe environmental conditions (where the insulation is exposed to conducting contaminants). This procedure does not cover special requirements, such as those for machines enclosed in gas atmospheres or machines subjected to strong chemicals, metal dust or submersion in liquid, etc. The procedure includes instructions for testing candidate systems in comparison with known reference systems, of the same type, having a proven record of service experience and interpreting the results of these tests.
The purpose of this procedure is to classify unsealed or sealed insulation systems for the machinery used in usual (normal) service or machinery used in severe environmental conditions (and falling within the scope of this recommended practice) in accordance with their temperature capabilities by test, rather than by chemical composition. Data from such tests may be used to establish the temperature classification of new insulation systems before they are service-proven. In order to provide data from which a base of reference for temperature classification can be established, service-proven (reference) unsealed or sealed systems should also be tested according to this test procedure. This document combines the procedures given in IEEE Std 275 TM-1992 (for unsealed systems) with those of IEEE Std 429 TM-1994 (for sealed systems).1
1 IEEE Std 275-1992 and IEEE Std 429-1992 are withdrawn