Gas Insulated Substations have become more frequent sites due to their  reduced footprint and high reliability of operation. But this reliability can be undermined by the presence of free moving metallic particles originating from breaker operations or mechanical vibrations. These particles can generate high electric fields locally initiating partial discharges (PD) within the insulation. Repeated partial discharges will eventually produce a flashover necessitating shutting down the GIS for repairs.

When partial discharges occur, they generate electromagnetic waves that propagate throughout the switchgear. GE’s PDwatch monitors these waves in the pressurized gas in the Ultra High Frequency (UHF) range. It is permanently fitted, generates alarms and can be interrogated remotely at any time so as to detect and eliminate emerging dielectric faults.