High volts pressure test failure
High volts pressure test failure
(OP)
I have tested two identical 6.6kV motor, water-filled and windings are XLPE-insulated. One passed, and one failed the test. This is a rare occurence. The failed test has a flashover at 5kV very close to the star point.
Historically, this motor had failed the test once before at the same location, and water may had entered through the damaged location as the copper conductor was exposed. After leaving the windings to dry overnight, the damaged section was cut away, insulation resistance displayed high value and new star joint was moulded. Second test was then performed, and breakdown happened again close to the star point.
Is water inside the wire to be blamed for the failed test? Why breakdown happen close to the star location, is it because it is being placed close to or touching the stator case? Any thoughts are appreciated.
Historically, this motor had failed the test once before at the same location, and water may had entered through the damaged location as the copper conductor was exposed. After leaving the windings to dry overnight, the damaged section was cut away, insulation resistance displayed high value and new star joint was moulded. Second test was then performed, and breakdown happened again close to the star point.
Is water inside the wire to be blamed for the failed test? Why breakdown happen close to the star location, is it because it is being placed close to or touching the stator case? Any thoughts are appreciated.





RE: High volts pressure test failure
RE: High volts pressure test failure
Dealing with wet wound motors can be difficult to impossible if not experienced working with them.
RE: High volts pressure test failure
RE: High volts pressure test failure
Test was done with the stator in a tank filled with water, windings including joints were submerged.
RE: High volts pressure test failure
We use special tapes for underwater splices that do not require heating, so I do not know much about your method. You could also look and see if the heating is causing the insulation to flow in a way that causes a thin point in it.