Life‐time characteristics of random wound compressed stator windings under thermal stress

Compression of windings is known to give thermal and performance benefits. The aim here is to investigate how the health of stator winding insulation systems are influenced by on‐tooth coil pressing. A set of compressed coils have been aged by exposing them to high temperatures. Winding insulation resistance (IR) was monitored during this process to experimentally validate whether compressed coils remained healthy in terms of electrical insulation. In this case, a single stress (i.e. temperature) model is used to predict the reliability of the compressed coils. Accelerated life tests have been conducted to inspect the life expectancy and thermal endurance of the compressed stator coils. The employed statistical model (Arrhenius‐Weibull) demonstrates that on‐tooth coil pressing reduces the life expectancy dramatically due to reduced turn to ground wall insulation dielectric strength.