Programmable protective device for LV distribution system protection

High quality electric power supply is the prime goal in the modern power systems around the world.One of the main ways to achieve this is the protection of the system which needs to be fast,reliable and cost effective.The objective of this paper is to provide protection of equipments in low voltage(LV)distribution system and thereafter to avoid their failure due to abnormal operating conditions.The proposed device provides protection for industrial,commercial and residential equipments by monitoring under voltage,over voltage and over current conditions using microcontroller,transistor and other discrete components.The microcontroller is the heart of this protective device which performs the major control of the device.The designed circuit can withstand the loads and the set voltage range so as to supply the connected load for any voltage variation between 220 and 240 Volts.It can be used to protect loads such as refrigerator,TV,VCR/DVD player etc.against undesirable over and under voltage conditions as well as surges caused due to sudden failure of power supply mains.This device can also be used directly as standalone equipment between the supply mains and the load.The over/under voltage and over current cut-off with time delay provides over/under-voltage and over current protection and also protection against any transients.