Calibration method of insulation oil tester based on the electric calculation for electrode structure

The calibration of the insulation oil tester (IOT) should simulate the actual operating state of device. It is recommended that the calibration apparatus have the same impedance with insulation oil vessel. This paper built models using finite element method and calculated capacitance values for different oil vessel structure. Besides, high-precision LCR electrical bridge was used to measure capacitances of different electrode structure and by the result of which the middle-grounded double capacitance divider vector signal measurement standard was developed. The experiment results indicated that the designed calibration apparatus could effectively match the impedance of the oil vessel and satisfy the traceability of vector quantity output value of the insulation oil tester with adequate accuracy.