Detection and Localization of Partial Discharge in Transformer Oil and Winding using UHF Method

Abstract

Transformers are important part in power transmission. One of the serious faults that is seen in transformers is electrical insulation failure. Insulation failure is usually initiated by partial discharges (PD). Due to high voltage stress, the fluid insulation in electrical system or a small solid portion can get dielectric breakdown, this is known as partial discharge and this does not create a space between the conductors. The accurate location of PD is an effective method for assessing the existing electrical insulation condition and preventing future accidents. PD is detected by many methods, but for onsite detection of PD, one of the efficient methods is sensing the electromagnetic waves radiated by the discharge source with a frequency range that can go up to 3GHz. In this technique Ultra High Frequency (UHF) sensors are mounted on the transformer tank to measure these waves. This provides a suitable solution for on-site detection of insulation failure in power transformers.