Hybrid electro-optic/inductive current sensor for high-voltage power system applications

Abstract

Preliminary results are reported for a novel hybrid electro-optic/inductive current sensor for high-voltage, power system applications. The sensor combines inductive current to voltage conversion with an optical modulator to provide isolated signal transmission from a high-voltage conductor to ground. The components of the sensor to be located in the high-voltage environment are passive, resulting in increased robustness over optical hybrid current sensor designs that require active electronics in the high-voltage environment. A further advantage of the passive design is that a power supply is not required in the high-voltage environment. The current sensor presented here is targeted at both revenue metering and protective relaying applications. Tests conducted in a high-current laboratory show the relative accuracy of the sensor to be stable to within from 200 A to 10 kA with phase stability within minutes of arc. Accuracy is presently limited by the temperature stability of the optical modulator which varies by about over the range from -40 to +60°C. Methods to improve the temperature stability are being investigated.