Abstract: An improved power supply capable of driving an external device at relatively high power levels for intermittent periods of time with the power supply driven by relatively low current input power which can vary widely in voltage. The power supply incorporates a step-up switching voltage converter module for increasing the input voltage to a higher value so as to charge an energy storage capacitor to an energy level sufficient to power the external device for said intermittent periods of time at relatively high current. The energy storage device voltage output is regulated by a step-down switching voltage converter module. Control signals sensing the voltage of the energy storage capacitor can be used to control energization and de-energization of the external device.

Abstract: An emergency lighting supervisory system monitors utility power so as to automatically connect emergency lights to a battery source when utility power fails. The system continuously monitors selected parameters and, automatically, periodically tests the system under simulated full-load emergency conditions and annunciates the results of these tests. Such periodic tests also enhance battery capacity. The system also provides a closed loop three-mode battery charging control circuit. It can optionally communicate its status as well as receive commands from an external computer or other source by means of a data communication interface.

Abstract: A power circuit for use in billet heating, surface heat treating and melting and protective circuitry associated therewith. The power circuit generally comprises a source of potential in series with a pair of inductances and an inverter module. The inverter module has two sections each comprised of a thyristor in parallel with a diode. A pair of series connected charging capacitors are connected across the source of potential and a load is connected from between the capacitors to between the two sections of the inverter module. Current flows through one thyristor, through the load and charges the capacitors. The capacitors discharge and a reverse current flows through the load and through the corresponding diode. This cycle is repeated then with the opposite section of the inverter module. A commutation failure protection circuit is provided which detects the voltage collapse condition accompanying a short circuit through the inverter module and when this occurs, it acts to shut off the thyristors.