Overvoltage protection

This paper focuses on the design of an electronic circuit which can be used at the ac input of loads - equipment in order to maintain the voltage supply (Vpeak - peak) constant, across them, despite the mains overvoltages. It describes a proposed electronic method for ac voltage supply stabilisation. The electronic circuit keeps the single phase voltage supply constant, according to nominal level (Vpeak - peak), even there is overvoltage up to 20% by mains supply (Fig. 1). The voltage stabilisation can be achieved by the PWM technique with a chopper ac-dc converter, controlling a transistor driver. As a result, by monitoring continuously the voltage supply - mains, by the use of the above PWM technique, may reduce the undesired overvoltages across a load - equipment and keep the nominal mains amplitude constant.