Design and development of internal UHF sensor for partial discharge detection in GIS

Partial discharge (PD) ultra-high frequency (UHF) sensors are widely used for condition monitoring and defect location in gas insulated substation (GIS). There are many designs of UHF sensors which can detect electromagnetic waves that radiate from PD sources. The general types of UHF sensors are disc, monopole, probe, spiral, and conical types with each type of sensor having different characteristics and applications. Sensitivity is an important index for evaluating the performance of UHF sensors. In order to test the electrical sensitivity, a simulation model to calculate the effective height is created by using FDTD Microwave software, and the size of UHF sensor are optimally designed. After that, an internal disk sensor is machined and tested with the GTEM cell. The results indicate that the effective height of UHF sensor is basically above 10 mm in the frequency region of 300MHz to 1500MHz.