Mechanical effects associated with the application of high voltage to generator stator bar insulation

For diagnostic technique, this paper demonstrates a link between electrostatically induced vibration and previously unexplained changes in electrical properties. Clearly the effects of vibrational electrostatic forces need to be recognised. However, a more rigorous theory is required to fully explain these links, particularly in the case of the time varying effects. In this case the movement of charge on void surfaces during the displacement and discharge processes probably needs to be taken into account. The possibility of quantifying delamination by a relatively low voltage measurement of the variation of capacitance or loss with voltage is of practical interest to the testing of high voltage stators since the practice of measuring delamination by applying voltages high enough to initiate discharging in the voids is inherently destructive. A simple technique which could be explored for this purpose would be to measure the AC capacitance at low voltage during the application of a relatively high (say up to 5 kV) DC voltage. In contrast to an AC test such a technique would not require bulky equipment