Multi-factor insulation system functional tests

Insulation system characterization in industry, through work in IEEE and IEC, is evolving from thermal aging functional tests to multi-stress aging functional tests. The latter approach includes all significant aging factors, affecting the insulation systems of specific equipment, in the functional test programs. The technical basis for using these complex tests and considerations in designing and interpreting them are reviewed, based on the experience obtained in using multi-factor tests, to evaluate the insulation systems of medium-size turbine generators in the author´s company. The relationship of these tests to single-factor functional and materials properties tests is discussed.