Patent ID: 8339090

Claim:
An apparatus operable in a wet environment for controlling the flow of electrical current to an electrical load, comprising: a pair of input terminals for connection to an AC mains supply; a pair of output terminals for connection to an electric motor and connected in a full power mode to said pair of input terminals; a voltage doubler circuit including a pair of diodes; a pair of direct current switching elements connected between said respective diodes and a common point; a controller; an interface connected to said controller for receiving external status signals; a switching arrangement responsive to signals from said controller to select said full power mode or a controlled power mode, and wherein in said controlled power mode said switching arrangement connects one of said output terminals to said common point so that AC output voltage is supplied to the electric motor through said switching elements; and wherein said controller is responsive to said external status signals to control said switching arrangement between the controlled mode and the full power mode, and in the controlled power mode to switch said switching elements in a predetermined sequence such that only one said direct current switching element conducts current during any one half cycle of AC output voltage applied to the electric motor.