Partial discharge activity has long been known to be an indicator of the presence of some deterioration mechanisms at work within, or on, the solid insulation of the stator windings of high voltage rotating machines. Initially the detection and use of the information or signals provided by these discharges relied extensively on the expertise of a few individuals and was very subjective in nature. Comparisons between different machines, or even between tests taken on the same machine over time, was highly onesided and made firm conclusions or judgments difficult to make. Advances in on-line detection and measurement of partial discharges has resulted in monitoring equipment that provides a knowledgeable user with reliable and repeatable information regarding the behaviour of an insulation system while a machine is in operation. These non-intrusive tests have the capability of providing a wealth of information which can be useful to formulate priorities and develop an appropriate maintenance strategy, especially where many machines are involved. This paper will highlight some of the observation and benefits of on-line PD testing using the results of more than 80,000 unique tests on rotating high voltage machines.
Earl Goodeve and Vicki Warren
Toronto, Ontario Canada