The Effect of Humidity on Partial Discharge Measurement

This paper is a study of the effect of humidity on partial discharge measurement in rotating machine. As we know, partial discharge measurement is effected by several factors and the humidity is one of the most important factors. To study the effect of humidity on partial discharge test, slot defect stator bar models were manufactured for data acquisition at 40%, 60% and 70% relative humidity respectively. The data were then analyzed by visual inspection to see the difference of three dimension distribution of H_n( (phi,q) and two dimension distribution of H_qmax(phi), Hq_n(phi), H_n (phi), H(q) and H(p). Statistical values were also calculated in order to compare the trend of those parameters at each level of relative humidity. The test result shows that visual inspection in the same stator bar model at each level of relative humidity has different patterns. In addition, the statistical parameters change upon the variation of relative humidity. Therefore, partial discharge measurement without consideration on humidity can lead to misinterpretation