Development of an UHF detection system for partial discharge measurement in transformer insulation

A test system to detect partial discharges in transformer oil insulation, using an UHF sensor has been developed. The UHF sensor is basically a duel arm Archimedean spiral antenna with a frequency response of 300 -3000 MHz. The UHF signal is amplified using an RF amplifier and analysed both in time and frequency domains. Various types of discharges have been created by means of a discharge simulator and characterised. Also, the location of a discharge site is identified by using two antennae and time of flight method.