Partial discharges in power transformers are localized electrical discharges that occur within insulation materials, which can weaken the insulation and lead to serious transformer failures. Monitoring and detecting partial discharges is crucial for the health and longevity of power transformers, as they are often early indicators of insulation degradation. These discharges produce pulses of energy and generate electrical noise, which can be identified using specialized sensors and monitoring equipment.

Early detection and continuous monitoring of partial discharges help utilities and operators take preventive actions, such as maintenance or replacement of the affected components, to avoid costly and unplanned transformer failures and ensuring the reliability and efficiency of power transformers in the electrical grid.

Ultra High Frequency (UHF) PD measurement utilizes the 300 Mhz-3 GHz range. In this range partial discharges produce fast electromagnetic impulses that are measured by antenna and a transducer. The UHF method is a non-destructive method for the transformer insulation system condition assessment. This frequency range is the most sensitive to small discharges, also it provides the most data for PD localization. This frequency range has high bandwidth and also is almost fully immune to outside interference.