Introduction: The work of the Partial Discharge (PD) Users Group has established a demonstrable link between partial discharge activity and substation environment particularly with regard to relative humidity and these phenomena are particularly detrimental to primary substation equipment that employs polymeric insulation materials.

This project employed a semi-permanent partial discharge monitor supplied by EA Technology (EATL) that can monitor and record surface partial discharge (ultrasonic), internal partial discharge (TEV), temperature and relative humidity in three indoor substation locations known to suffer from high levels of humidity.

Objectives: The specific aim of the project is to further research the potential link between environment and partial discharge activity and to trial the cost effectiveness and practicality of remote partial discharge monitoring of substation equipment on the Electricity North West network.