Partial discharge estimation based on radiometric and classical measurements

Partial Discharge (PD) is characterized by high frequency current pulses that occur in the interior of high voltage (HV) apparatus. It involves gas ionization processes within insulators and can therefore indicate insulation defects. Low levels of PD are not necessarily of urgent concern in the context of safe operation of plant but they may gradually increase with the time, until complete discharge (flashover) occurs causing catastrophic plant failure. PD levels and their occurrence are therefore monitored (usually periodically) during the operational lifetime of HV equipment. This paper compares PD measurements made using three different techniques: the `classical' method described in IEC 60270 [1], the high frequency current transformer (HFCT) method and a free-space radiometric (FSR) method. The comparison is made with a view assessing the practicality of replacing the classical quantitative method with other more convenient/cheaper methods.