ABSTRACT

Every electrical and electronic appliance is designed to work perfectly at a certain input voltage. In Nigeria, household electrical and electronic appliances are designed to work properly at 220VAC, 50Hz and most of the times the voltage supplied from distribution companies are as low as 80VAC making this appliances to work under threat of low voltage supply. This low supply voltage causes these appliances to malfunction and in most cases damage them. Since the electric power supply/distribution companies are unable to provide the consistent adequate voltage level (220VAC) demanded by these sensitive appliances, therefore there is need for consumers to protect the appliances from damage and ensure their safe operation, hence the use of automatic voltage stabilizers to improve the situation. In this research work, an Atmega 328p microcontroller was programmed to monitor the input voltage from distribution companies and if voltage level is between 80 VAC and 250VAC, it gives a constant output voltage of 220VAC (±6%) required by the appliance. In doing this, it constantly varies the turn's ratio of the Auto-transformer, initiating a step-up or step-down operation of the transformer so that a regulated voltage of 220 VAC (±6%) is obtained at the stabilizer output. The system also constitutes of a 16 by 2 liquid crystal display for the display of both the input and output voltage range.