Unique EHV current probe for calibration and monitoring

A unique current probe for high-voltage systems has been developed and placed into operation. The current measurement system is based on a high-precision split-core Rogowski coil paired with a hybrid optical data link. This system can measure steady state and transient currents of greater than 60 kA with excellent linearity. It is designed to check and verify the accuracy of high-voltage metering current transformers and to function as a clamp-on stationary current probe for wide-area measurement systems. This paper presents a technical description of this hybrid optical current probe, laboratory and calibration test results, installation procedures, and initial operational experiences. Applications, including on-line current transformer calibration, and the economic impact of improving measurement accuracies are presented.