Acoustic monitoring of insulation delaminations during thermal cycling tests on a stator bar

This paper describes a novel acoustic monitoring technique of insulation delaminations during a thermal cycling test (TC) on a stator bar. Acoustic signals emitted from insulation delaminations within the stator bar were continuously recorded during a TC test. An increase in measured acoustic signals indicates insulation delaminations within the stator bar under test. Dissipation factor tests, partial discharge tests, tap tests, and dissections were performed. Those diagnostic test results were compared with the acoustic test data to verify insulation delaminations. The acoustic monitoring system can indicate which cycle insulation delaminations occurred and when they occurred in a given thermal cycle during a TC test.