EVALUATION OF FIELD AGED CROSS-LINKED POLYETHYLENE CABLES BY PARTIAL DISCHARGE LOCATION

Partial discharge sites were located in several field aged crosslinked polyethylene insulated medium voltage cables, using a newly developed instrument. Subsequent AC breakdown tests indicated that, with partia l discharge inception voltages lower than 3 times operating voltage, t he failures occurred at the partial discharge sites. In all cases, the failures originated at the sites of long water trees which affected t he cables at discrete locations rather than uniformly over their entir e lengths. Attributes of a partial discharge locator capable of perfor ming in-situ non-destructive diagnostic tests on cables are discussed and field application procedures are described.