An Optically Isolated Hybrid Two-Stage Current Transformer for Measurements at High Voltage

The development of a high-voltage reference current measurement system for on-site/in-situ calibrations in power systems is described in the paper. The system is based on an optically isolated hybrid two-stage current transformer with electronic circuitry that performs A/D conversion. It features a fiber optic link for data transmission to a ground station, and a laser-driven fiber optic link for supplying power to the electronic circuitry of the remote module at high voltage. The ratio accuracy of the current measurement is estimated to be better than 100middot10^-6