GIS, always expected to function and work with extremely high level of reliability.GIS or gas insulated substation incorporates SF6 as an insulating medium which is an inert and stable gas. Prolonged sparking and discharges in SF6, particularly under high moisture content produces corrosive and toxic byproducts that will contribute to corrosion of metallic and insulating components.
It is observed that all these defects generate PD activity prior to complete failure. Thus PD analysis holds high importance in insulation diagnostics for GIS. Partial Discharges if present in the insulation system generates Ultra High frequency electromagnetic waves in the frequency range of up to 10GHz. IEC 62478 briefly states the use of UHF method for detection of partial discharges. The same principles can be applied to detect the PD from GIS.
The ohv diagnostic instrument utilizes technologies which are at Zen of industry standards. The UHF PD assessment is performed by optimally tuned hardware to measure PD signals of up to 2 GHz. The measurement is performed with corroboration to the supply frequency. The PD assessment instrument are available in single channel & multichannel configuration with options of 3/6 measurement channels.
The detection of partial discharge activity can be done either periodically or through continuous monitoring.
- Partial discharge detector for periodical measurement