Abstract: An emergency power supply including an input for connection to a power line, an output for connecting the input to electrical equipment so as to supply power thereto from the power line, a supplemental power supply connected to the output and adapted to supply power to the electrical equipment upon a power abnormality in the power line, an electrical energy storage means connected to the supplemental power supply and adapted to supply electrical energy thereto; and a circuit for detecting the abnormalities in the power line.

Abstract: A circuit apparatus including a circuit interrupter connected between an AC supply and electrical equipment to be protected and operational in a first condition to transmit power therebetween and operational in a second condition to interrupt power transmission therebetween, a control circuit for producing the first condition in response to normal supply voltage and for producing said second condition in response to abnormal supply voltage, a delay circuit connected to the control circuit and adapted to produce a minimum time delay between successive occurrences of the first condition, an overvoltage circuit adapted to produce the second condition in response to a voltage from the supply that exceeds a predetermined maximum level, and an undervoltage circuit adapted to produce the second condition in response to a voltage from the supply that is below a given threshold level.