Method to measure CVT transfer function

In this paper, the results of tests on a 275 and a 400 kV capacitor voltage transformer are presented. The objective has been to determine the transfer function of the CVTs in the Scottish Power extra-high-voltage (EHV) system, which in turn can be used to compensate for the errors at harmonic frequencies. As a primary requirement, the magnetic elements of the capacitor voltage transformers (CVTs) must be excited at nearly their nominal magnetic states. A test procedure is presented, which does not require CVT disassembling and/or modeling and ensures that the above essential requirement is satisfied. The effects of burden on the frequency response is also presented. It is confirmed that the size and nature of burden affect the CVT frequency characteristic.