System power control

This disclosure relates to minimising the losses in a power drive system. In particular it relates to detecting excess power and automatically activating and deactivating a system to redirect the excess power away from the power drive system into the supply grid. A method of controlling power for a system is disclosed, said system comprising a first controller (14), a motor (16) for driving a load, and supply means (12) for supplying power to said motor (16); said method comprising: monitoring a signal representative of power within the system; using said signal to determine if the power within the system exceeds a first threshold; and if it is determined that said first threshold has been exceeded, activating the first controller (14) to supply power from the system to an output.