Experience with testing of electrical insulation using non-destructive PD test

The requirement of any power generating utility is to achieve reliable and trouble free power generation in their facilities. Systems for online quality and reliability assessment of power equipment have became very popular in recent years. By having access to power equipment while in normal operation, plant engineers have been able to avoid catastrophic in service failures, costly forced outages of power generators and associated equipment, as well as prolong significantly the life of the equipment. By early detection of developing problems on power systems, maintenance can be scheduled promptly and only when necessary. Planning of work and resources can be done well in advance, which will tremendously reduce the cost of such intervention. Also by performing test before and after repair it is easy to control the effectiveness of repair. Online monitoring systems which are non destructive, reliable, quick and easy to use, have in fact become a kind of standard in many power utilities worldwide. A major problem in HV power equipment is electrical insulation. One online test for the integrity of power equipment is the PD (partial discharge) test for electrical insulation. The PD test, besides testing power generators and motors, is also applicable for factory screening of stator bars, testing HV power cables and power transformers