Difference and Analysis of Mechanical Vibration Signal Characteristics between Mechanical Defects and Partial Discharge Defects of Gas Insulated Switchgear

Mechanical defects and partial discharge (PD) are two typical defects of GIS equipment. Both of them can cause abnormal sound vibration, which may lead to misjudgment in field detection and threaten the safe operation of the equipment. To explore the difference between mechanical defect vibration and PD vibration of GIS, in this paper, based on the actual operating GIS, the vibration detection and PD test on disconnector chamber, potential transformer chamber with normal and abnormal sound status were carried out. The vibration signals under cases of normal, mechanical defects, PD were obtained. Difference analysis of the signals from time domain, frequency domain and generating mechanism was carried out. Results show that GIS mechanical defect vibration is mainly 100Hz, accompanied by 100Hz frequency doubling. The frequency spectrum distribution is basically in the range of 0~4kHz, and the waveform have sinusoidal signs. The PD vibration signal characteristic is unique, showing a strong and weak alternating double signal cluster waveform with a period of 20ms, which has strong intermittency and 50Hz correlation. The frequency spectrum contains a large number of 50Hz and 100Hz multiplier components. Signals are concentrated at 2~4kHz and 6~8kHz, and also distributed at 8kHz and above. The results provide a theoretical basis for GIS fault identification.