The evaluation of a PRPD pattern, enables you to determine the kind of fault within the test object. Most partial discharge (PD) faults, such as insulation damages, voids, surface discharges, or floating points, will have completely different PD patterns. The typical criteria for classifying these patterns are:
- Phase position of the maximum partial discharge
- Phase position of the starting electron
- The gradient of discharges
- The shape of discharges in the positive and negative half-cycle
- The absolute value of discharge in pC or nC
- Short-time or continuous discharges
For successful interpretation, it is also necessary to get as much information as possible about the test object and its environment. Such information could include temperature, installation condition, age of the test object, previous faults, or weather conditions.
It is useful to store typical PD patterns of known faults in an archive. This, can be done by using the GISmonitor software in combination with Power Diagnostix’s ICMexpert software. This customer-specific database will be helpful for later evaluation on other test objects.
