Design, Construction, and Effectiveness of Electrical Outlet Box with Built-in High and Low Voltage Cut-off and Power-on Delay Circuit
The electrical outlets installed in houses and buildings have no means of protection to prevent the plugged-in electrical appliances from the risk of being hit by the voltage fluctuations, and sudden loss and recurrence of electricity. This study designed and constructed an electrical outlet box that disconnects the appliance from the power source when high and low voltage levels occurs. It also delays the connection to the power source at normal voltage level. It comprises a plastic enclosure securing therein the interconnections of a power supply circuit, a high and low voltage cut-off circuit, a power-on delay circuit, a relay driver circuit, a double pole double throw relay switch, and electrical outlet. The variable alternating current transformer was used to apply the high and low voltage levels to the electrical outlet box where the industrial fan was plugged. Results showed that the electrical outlet box disconnected the industrial fan from the power source at 231 and 199 V. Also, there was a four-minute waiting period before the industrial fan was connected to the power source when the 201-229 V was applied. Therefore, this device is effective in preventing appliances from being hit by voltage fluctuations and sudden loss and recurrence of electricity.