Abstract: A secondary power system eliminates the need for an automatic transfer switch and permits simultaneous supply from different sources. Primary power is rectified and connected to a DC bus, an AC generator has its output rectified and connected to the DC bus, and a storage battery is also connected to the DC bus. Current on the DC bus is inverted to AC to provide an uninterrupted power supply. The system is connected to a household electrical system by a power distribution panel which can be installed in a home prior to the secondary power system and can facilitate installation of the secondary system. The distribution panel can selectively bypass the secondary system and can disconnect non-vital loads when primary power is not available. The generator is powered by an engine using gasoline, natural gas or water, which can also power other systems, such as air conditioning, with exhaust heat or rotary motion.

Abstract: In a backup power supply, a pair of back-to-back auxiliary transformers are used to isolate the inverter control source, the inverter, and the a.c. line. A single-pole double-throw relay is used to selectably connect the a.c. line to the power supply or the auxiliary transformers to each other. When the auxiliary transformers are connected, the inverter operates and the a.c. line is isolated from the power supply and no power can feed back from the power supply to the a.c. lines. When the a.c. line is connected to the power supply, the auxiliary transformers are unconnected and the inverter is inoperative.

Abstract: A method and apparatus for detecting the loss of regulation in ferroresonant transformer is disclosed. The flux in the magnetic shunts is sensed by a winding. The resulting signal is differentiated. If the differentiated signal contains pulses, regulation is present, if no pulses are found the transformer is not in regulation.

Abstract: A ferroresonant transformer having dual outputs electrically and magnetically isolated from one another. The transformer includes a core, a primary coil on the core adapted to be connected to a source of alternating current, and two pairs of secondary windings located at axially opposite ends of the primary winding. Each of the secondary windings is coupled to the primary through a steel shunt located between the primary winding and the respective secondary winding. Each of the two secondary windings has a resonant winding associated therewith and connected to a ferrocapacitor to produce an inductive coupling. Each of the secondary windings has a pair of output terminals, each of which is connected to a separate load, with the effect that the loads are electrically and magnetically isolated from each other.