Design and Simulation of Automatic over and Under-voltage Protection Systems for Home Equipment

Voltage magnitude fluctuation in AC mains supply is a common issue in power systems. Electronic devices in these conditions are sensitive and can be easily damaged, making it crucial to have a protection mechanism to safeguard the load. This paper aims to design a protection system that can protect low-power electrical appliances like home appliances from Undervoltage and overvoltage. The protection system designed in this paper possesses a tripping mechanism that is activated by the output of two comparators; one for undervoltage and the second for overvoltage. The designed protection system trips the loads in the event of the input voltage falling below 198 V or above 243 V. Two window comparators, formed from a quad comparator IC, generate an error output if the input voltage exceeds the voltage window. A relay is then operated to cut off the load for safety reasons. The designed system is simulated using Proteus 8.1. As a result the protection system trips off the load when the supply AC mains voltage is below 198 V or above 243 V; and when the supply voltage is between 198 V-243 V, the load is not disconnected. The system is fully automatic as it switches on the load when the supply voltage restores to its normal range. Therefore this paper is designed to protect over and under voltage for home appliances automatically to make the equipment safe.