Abstract: A circuit is provided which responds to single or multiphase low or lost voltage situations and in the case of multiphase systems to phase reversals or shifts to disconnect a single or multiphase load from its source. A timing circuit is provided which prevents reactivation of the load until a prescribed time interval has elapsed. The reactivation may be either automatic or manual.

Abstract: Circuits for increasing the efficiency of fluorescent tubes by openings one side of all of the filament circuits of the tubes in response to flow of plasma current. The circuits may be employed in conjunction with the circuits of Lucetta U.S. Pat. No. 3,954,316. It should be noted that solid state relays could also be employed so that filament current, although not completely terminated, would be substantially terminated and filament losses would be inconsequential.

Abstract: There is provided a luminaire primarily for use with exit signs and other emergency-type lighting comprising a series string of low-voltage, extremely long-life bulbs positioned within an enclosure for protection and electrically connected to a standard base whereby luminaires having lives of 10 to 30 years may replace standard bulbs without the requirement of retrofitting.

Abstract: There is provided a luminaire primarily for use with exit signs and other emergency-type lighting comprising a series string of low-voltage, extremely long-life filaments positioned within a sealed enclosure for protection and electrically connected to a standard base whereby luminaires having lives of 10 to 30 years may replace standard bulbs without the requirement of retrofitting.

Abstract: A protection circuit for multi-phase motors provides circuits for protecting a motor against low voltage, phase reversal or loss of a phase and other improper operating conditions on both the line side and the motor side of the main motor contactors. The line and motor side circuits are interrelated such that an unsafe condition on either side of the contactors causes the contactors to be opened. A time delay circuit on the motor side of the contactors prevents interruption of the holding circuit until conditions on the motor side of the contacts have been established and sensed for operation, proper or otherwise, during motor start up.

Abstract: A switching circuit is comprised of a triac in series with the electrical load across an AC power source. The triac commences to conduct only after a unidirectional, gate-controlled SCR is conducting. Conduction of the SCR drives the gate of the triac enabling conduction. In turn, the SCR is controlled by a circuit network which regulates the potential at the SCR gate and is responsive to an external device which may be a photodetector and movable shutter in combination with a light-emitting diode (LED). Load conduction commences in synchronism with the source voltage crossing of the reference axis in a selected direction. When the load is turned off, an integral cycle is provided.