Enabling 11/500 kV test transformer for 11 kV equipment testing

This paper presents a solution to the problem of quasi-steady-state over voltages occurring across 11/500 kV test transformer (originally designed to solve the insulator contamination problem/design in deserts and coastal areas), thereby making it suitable for separate source voltage withstand tests of equipment with rated voltage of 11 kV and below. Further, it also presents a theoretical and experimental analysis of the recovery over voltages and means to prevent their occurrence. Besides, frequency response, harmonic analysis of the saturation impulse current and behaviour of the delay cable adequately supported with mathematical models/digital simulations were also carried out. The agreement between the results of experimental and those by analytical method, in certain cases, enabled to devise methods for prevention of initial and recovery over voltages on the test system.