Use of a Multichannel Analyzer for Corona Pulse-Height Distribution Measurements on Cables and Other Electrical Apparatus

A method in which use is made of a multichannel analyzer to measure the distribution of the corona pulse heights of insulating systems of various electrical apparatus such as transformers, capacitors, and cables is described. Suitable pulse-shaping circuitry is used in conjunction with an RCL-type corona pulse detector to provide a basic sensitivity level of 1 pC and corona pulse resolution limit of about 10-15 ,μ s. A calibration technique is described and particular attention is given to the interpretation of calibration results obtained under high ambient noise conditions normally prevalent in electrical apparatus production areas. It is shown that electrical interference may degrade the corona charge resolution of the analyzer display to as much as 4.0 pC as compared to the half-peak width value of about 0.5 pC in the near absence of noise. Typical corona pulse-height distribution spectra obtained on solid dielectric insulated power cables are presented.