Characteristics analysis of sensors for on-line partial discharge measurement

As the demand of high power system reliability, condition based maintenance (CBM) becomes a better solution for maintaining equipment reliability. According to the diagnostics of CBM, one can estimate the condition of insulator, and find an optima strategy. Among them, on-line partial discharge measurement is one of the most important diagnostics assessing the condition of insulator. However, the majority problem of on-site measurement is the noise distinguishability. Therefore, different manufactories develop their own methods to overcome this difficulty. Unfortunately, different methods utility different sensor varying with bandwidths, and they are difficult to compare the measurement results with each other. Based on these problems, authors test different commercial sensors to assess their characteristics. Authors inject different calibrating signals into the test system including a voltage transformer, and measure the sensitivities, bandwidths, and waveforms of partial discharges. According to results, magnetic sensor has similar sensitivity with coupling capacitor, and UHF sensor has better signal to noise ratio. Based on this paper, one may compare different measurement results from different instruments to estimate the condition of insulator.