A generator controller (4) is provided which is able to detect and respond to failure of a generator output voltage sensor, whilst being able to distinguish voltage sensor failure from output voltage collapse due to the presence of an overload or short circuit condition. The presence of a voltage sensor failure is indicated by the measured output voltage being below a first voltage threshold whilst the output current is also below a current threshold.
A method of protecting an electromechanical power transfer system from excessive peak electrical potentials, the power transfer system comprising a prime mover, a dynamoelectric machine coupled to the prime mover for generating multiphase alternating current (AC) power, and at least one multiphase AC electrical load coupled to the dynamoelectric machine by way of a multiphase AC power bus, the dynamoelectric machine having a control coil responsive to control current for varying power supplied to the electrical load, comprises the steps of: analysing electrical potentials on the power bus to generate analysed power bus characteristics; comparing the analysed power bus characteristics to predetermined power bus characteristics; simultaneously shunting power across the power bus and reducing control current to the control coil for the dynamoelectric machine when the analysed power bus characteristics approximate the predetermined power bus characteristics to reduce the measured electrical potentials; and simultaneously terminating the shunt of power across the power bus and restoring the level of control current to the control coil for the dynamoelectric machine after a selected delay period to automatically restore power to the electrical load.
