Abstract: A reserve power source, switchably connected to a network between a primary power supply and a load, provides an auxiliary power signal to the load when a power failure condition is detected in the signal from the primary power supply. The reserve power source includes a circuit for instantaneously detecting and switching upon the occurrence of a power outage. An overvoltage/noise detector circuit is included to detect when either a sustained overvoltage condition or a high, short duration overvoltage condition occurs. A low voltage detector circuit is included for detecting a low voltage, or brown-out, condition. When an overvoltage or low voltage condition is detected, a preferred embodiment of the invention switches the load to the auxiliary power signal within one-half cycle of, but in zero-crossing synchronization with, the primary power signal.

Abstract: An alternating current power source, which is to provide an auxiliary alternating power signal output to a load after switchover from a primary power signal, includes a phase switching circuit which causes the auxiliary power signal to immediately switch phases when a phase imbalance is detected between the primary power signal which existed immediately prior to switchover and the reserve power signal which exists immediately after switchover. In a preferred embodiment the circuit includes a diode and capacitor serially connected between a shutdown output and a synchronizing input of a pulse width modulator integrated circuit.

Abstract: An alternating current power source which controls its own alternating current output through a feedback circuit which monitors the alternating current output is disclosed. The power source can be used as a backup to a primary power supply which provides power to a load. The present invention continuously monitors such primary power supply to detect power interruptions in the primary power supply. When an interruption is detected, monitoring logic circuitry of the alternating current power source disconnects the primary power supply from the load and energizes line driver circuitry of the present invention which provides the alternating current output. When the power interruption ceases, the monitoring logic circuitry reconnects the primary power supply to the load and disables the line driver circuitry so that alternating current is not provided by the present invention to the load.

Abstract: A visual signaling system including at least two light sources. Graphic indicators positioned adjacent to the light sources for identifying the light sources. The indicators including codes for identifying a particular light source with which it is associated and permitting one to distinguish one light source from another relying on the code.The indicator, in one form of the invention, may consist of a band positioned adjacent to the light source with the code being the extent of shading of the band. In one form of the invention, a circular band is provided with discrete levels of shading corresponding to particular light sources. The system may be a warning or alarm system with the extent of shading being a function of the relative importance of the particular light source.