Whenever the electricity supply fails or there is a voltage fluctuation beyond the present acceptable limits, overvoltage protector disconnects the appliance from the mains, continues monitoring and the mains supply reconnected only when supply resumes and / or the voltage stabilizers within the limits.

As a further safeguard, the supply is only connected to the appliance when the voltage has remained within the limit for predetermined time normally three minutes.

Overvoltage protector has a fast response time within one cycle of less than 20% in which case overvoltage protector responds in about one second. This is important so that overvoltage protector will not disconnect as result of the initial voltage drop on the startup of appliances.