The University of British Columbia

A 138 kV optical voltage transducer (VT) using shielded distributed electric field sensors is presented for use in high-voltage (HV) electric power transmission systems. Since HV and ground are kept far apart, the VT does not require oil or SF6 for insulation; instead, it uses the environmentally friendly dry nitrogen as an insulating gas. A prototype has been tested for accuracy under various severe field disturbances including the presence of conductive pollution-like layers on the insulator and the presence of other HV sources nearby. The test results show that the VT meets IEC 0.2% and IEEE 0.3% accuracy classes under these extreme field disturbances. Data that demonstrates wide bandwidth of the VT are also presented. Another prototype has been tested and has successfully passed standard IEC HV dielectric withstand tests including power frequency withstand at 275 kV, partial discharge lt;5 pC, lightning impulse tests (BIL) at plusmn;650 kV, and chopped impulse tests at -750 kV