Yes it was an AC hi-pot (27400 VAC). This test was the final package test after assembly. Only one side of the end plate was removed because we had performed a bearing and seal inspection after all the other run tests had been performed and the small end plate around the bearing housing hadn't...
This is a new motor, 13.2 kV TEAAC. Corona was visible on the drive end on the stator and rotor during hi-pot testing on each phase. This was the only end I could see as the bearing shild plate was not installed on this end at the time of testing.
While hi-pot testing a 4500 HP motor, it was noted that there was considerable "popping and cracking" noted and I could visibly see arcs jumping throught the front end of the rotor to the stator. The operator stated this was "normal and, as long as the hi-pot machine didn't trip, was acceptable...
