Gas insulated system (GIS) is a compact metal encapsulated switchgear consisting of several high voltage (HV) components such as disconnectors and circuit breakers that are insulated with sulfur hexafluoride (SF6) gas. It offers advantages such as high power transmission and less area occupancy. Several kinds of defects develop during operation, which produce partial discharges (PDs). Although the magnitude of discharges is small but gradual, progressive deterioration due to the PDs in GIS leads to catastrophic failure. The PDs can be detected using ultra high frequency (UHF) sensors. Each kind of PD affects GIS differently, hence it is crucial to detect and classify PD signals at an early stage to prevent serious power outage. This research aims at the development of ultrawideband UHF sensors, classification of PD defects and simulation of PDs induced UHF signal propagation in GIS sections.