Winding immersion testing: `Are our fears all wet?´

Immersion testing of AC form wound stator windings to qualify sealed insulation systems for extreme environments is an industry practice. Questions have been raised as to the validity of the immersion test. The immersion test procedure is reviewed, the process and results of the test are described, and fears that have been raised of possible degrading effects on the insulation life due to the immersion test by motor manufacturers are discussed