Partial-discharge measurements for insulation quality

There is one common factor that, in different forms, runs throughout the entire electrical and electronics industries. That factor is the requirement for insulation that gives the necessary mechanical, thermal and electrical properties needed for particular applications. The presence of partial discharges indicates some defect within the insulation that is very likely to affect the expected life of the particular item. Partial-discharge testing techniques can therefore offer a very sensitive means of assessing insulation quality either on individual component parts or on complete equipment assemblies. The author describes the aims and applications of the technique and also tackles the practical problems that can be encountered. The author discusses the discharge mechanism and detection techniques. Routine and on-site testing are discussed. The effects of interference and interference rejection also discussed