Field Calibration Method of GIS Partial Discharge UHF Sensor Based on Network Analyzer

In order to ensure the effectiveness of ultra-high frequency (UHF) method for gas-insulated switchgear (GIS), detection sensitivity verification is necessary. This paper proposes a field calibration method based on the S21 parameter of the network analyzer. The S21 is defined as the forward propagation coefficient that means the attenuation between the two sensors of the dual port network on GIS in the bandwidth spectrum. The forward transmission coefficients measured by equivalent pulse and the network analyzer conforms with frequency spectrum characteristics. The average attenuation of a gas barrier insulator is 2.4 dB; The L-junction is 5 dB; The straight arm of a T-junction is 9 dB and the vertical arm of a T-junction is 12.3 dB. The attenuation law of the forward transmission coefficient of the network analyzer is consistent with the propagation law of electromagnetic wave in the partial discharge in GIS. Therefore, it can be used as a field verification method for GIS partial discharge UHF sensor, which can reasonably arrange UHF sensor and improve the effectiveness of partial discharge detection of the GIS.