Compact system for onsite calibration of 1000 kV voltage transformers

Abstract

This study describes the development and evaluation of a compact system for onsite calibration of 1000 kV voltage transformers in ultra-high-voltage (UHV) AC power transmission projects. The proposed compact system consists of a 1000 kV electromagnetic voltage transformer as a standard, a high-voltage resonant power supply, and a voltage transformer test set, which are assembled and mounted on a calibration truck. The developed system accuracy is 0.05% in ratio and 0.058 mrad in phase angle, respectively. Also, the total basic uncertainty is about ±0.028% and ±0.03 mrad under field conditions. The compact system can be automatically set up and taken down quickly on site requiring no substation cranes or utility operating crews. It has successfully undergone complete field tests and calibrated 63 1000 kV voltage transformers in total at 5 UHV substations. The feasibility of an automatic and efficient approach to calibrating UHV voltage transformers on site has been demonstrated.