Utility system high voltage-level calibration. We compared the output of a precision standard to the voltage output of station capacitor voltage transformers. In most cases, we energized the station device from a mobile source up to 120kVAC.
Results of the calibration isolated errors in the secondary circuit (voltage drop in protective devices and relays), in changed secondary burden (from upgrades to relaying) and in RTU calibration. A final calibration at the control room would synchronize the readings with the control center so that all circuits indicated the same level.