抄録
It is important to improve the sensitivity of partial discharge (PD) sensors for diagnostics of high voltage electric apparatus. However when noise similar to the PD signal is picked up by sensors, false detection will be made. PD pulses have about one nanosecond rise time in the SF6 gas insulation. These pulses propagate in the apparatus to PD sensors in the form of the voltage oscillation, the high frequency current, and the electromagnetic radiation. We succeeded to detect the periodic damping waveforms by PD sensors installed at the GIS. These waveforms have information of the PD.
In this paper, we investigated the characteristics of three types of PD sensors, by putting high frequency signals in the form of sine wave and pulse into test apparatus. We found that these sensors can detect some 100MHz high frequency signals and one nanosecond rise time pulse similar to PD signals in SF6. Frequency characteristics of waveforms detected by the PD sensors are influenced by a test circuit.
