Abstract: An emergency power supply includes a rectifier component for stepping down and rectifies the input AC signals from the primary power line, wherein the rectifier is coupled to a voltage regulator to allow for battery charging, and the stabilizer is further connected through a switch to a system control circuit which controls the power source. The output of the stabilizer is also connected to a DC to DC converter, such that the power source from the primary power line can also supply loads in normal power conditions. In case of power outage, the microprocessor enables the switching element thereby allowing the storage battery to be connected, so that the output current is stepped up and passed to the DC to DC converter for generating load current. The emergency procedures can thus be initiated before the primary power line goes down, avoiding disruption in system operation.