5 kV, 10 kV and 15 kV insulation testing: guard terminal

During insulation testing we are often so preoccupied with the resistance of the actual insulator, we forget the resistance path on the outer surface of the insulation material. However, this resistance path is very much a part of our measurement and can dramatically affect our measurements. This paper looks at the benefits of guard terminals in testing various devices that have long surface leakage areas of insulation.