Insulation deterioration of 11kV alternators - Pioneer Mill

Insulation testing of electrical equipment is normally carried out in the simplest form by using a HV megger or with a HV test rig leading to a polarisation index. The absolute megger tests on the two 11 kV machines at Pioneer showed the insulation as being in good condition, as did a visual inspection. Tests with the HV test rig, however, indicated a potential failure situation and these were discontinued before normal maximum test voltage could be reached.