Comparative investigation of lightning impulse tests on electrical submersible pump motors

This paper investigates the capability of some samples of electrical submersible pump (ESP) motors to withstand standard basic "lightning" impulse level (BIL) and to get the destructive voltage for all phases. Tests were performed on samples from different ESP vendors and with a voltage rating between 1 kV and 2 kV, to fulfill the lightning impulse standard test requirements. All the tested ESP motors showed a decrease in the terminal impedance between one line and the motor casing with the frequency, i.e. low-pass filter effect for fast transient overvoltages. In addition, all ESP motors passed the standard lightning impulse withstand tests with no significant change in the terminal impedance. Used ESP motor failed at 37 pu of the BIL, while all the new ESP motors failed at much lower level up to 22 pu. This trend is attributed to the better oil infiltration in the used motor during runtime than in the new motor with zero runtime.