Abstract:

Ultra-high frequency(UHF) detection method is widely used in discharge detection for GIS equipment, the performance of UHF sensor affects the reliability of detection results. In order to avoid the poor performance of the sensor, the test results are not very instructive to the field work, so it is necessary to carry out parameter detection periodically for different manufacturers and different models of UHF. In order to avoid the difference of the effective height of sensors obtained by different experimenters, rectangular UHF sensor is taken as the object, and the angle between the long axis of the sensor and the surface hole of GTEM chamber is obtained, and the change rule of the effective height before and after the shielding cover is installed on the outer surface of the sensor. The test results show that the effective height corresponding to the angle of 90°is the smallest, far less than the assessment value of 8 mm stipulated by the state grid corporation specification, the effective height corresponding to the angle of 0°is the largest, and the effective height value at the angle of 180°is slightly lower than the corresponding value of 0°. The main reason for the change of the effective height value with the angle is that the sensor has directivity. When the sensor is covered by a shield cover, the effective height decreases slightly, and the amplitude decreases by less than 6% compared with that before the shield cover. The research results provide a reference for standardizing the process of obtaining the effective height of UHF sensor by using GTEM cell.

Key words: Installation angle, shield cover, effective height, UHF sensor