Abstract: A system for reducing the voltage of an AC electrical supply to a load for the purpose of energy efficiency, comprising a transformer and power converter in circuit between an AC electrical supply and a load, and a bypass switch S to cause the transformer to be taken out of circuit and to connect the electrical supply to the load in the event of a sustained overload of the transformer. The system includes means (14) to measure the temperature of the transformer, means (17) to measure the electrical current in the circuit and control means (15) receiving signals from the sensors (14, 17) and to operate bypass switch S to bypass the transformer and allow it to cool. A fuse F2 and thermal cut out device (16) are in circuit with the secondary winding of the transformer as failsafe means to interrupt the supply to the transformer in the event that the bypass switch fails to operate.

Abstract: A voltage regulation device adapted for connection to a varying electrical supply and to regulate the voltage supplied to certain selected circuits whose loads benefit from voltage regulation. The device comprises a PWM or phase angle switched autotransformer which is sufficiently compact and lightweight to be incorporated into a standard electrical consumer unit which has separated circuits, ie, those whose loads benefit from voltage regulation and those whose loads do not, such that the former may be controlled by the device to operate at a constant and reduced voltage thus ensuring a reduction in energy consumption and the life enhancement of the appliances connected to the device. The operating temperature of the autotransformer is controlled by temporarily increasing the output voltage of the autotransformer in the event of overheating.