Sundstrand Corporation

John W Diemer

Michael D Teagardin

Jack B Miller

An electrical power transmitting system (50) in accordance with the invention includes an alternating current electrical power generator (12) for producing alternating current on an output having a specified maximum; at least one electrical load (22) which is coupled to a point of regulation (16) in the electrical transmitting system; a feeder (14) having a specified maximum voltage drop, a length extending between the output and the point of regulation for transmitting the alternating current to the point of regulation, an inductance having an inductive reactance at a fundamental frequency of the alternating current, a capacitance (54, 66, 80 and 100) in series with the inductance having a capacitive reactance at the fundamental of the frequency of the alternating current which cancels at least part of the inductive reactance at the fundamental frequency of the alternating current to provide a reduced impedance in the feeder at the fundamental frequency of the alternating current to produce a reduced voltage drop which is less than the specified voltage drop; and the feeder having a minimum weight per unit length providing a maximum current carrying capacity equal to the specified maximum at the reduced voltage drop.

Electrical power transmitting system with reduced feeder size and method

This invention relates to a bus configuration for a dual channel variable speed constant frequency motor/generator aircraft power system providing for both power generation and engine starting. The subject invention provides for isolation of faults which can occur in long power feeders. Further, the subject invention provides for a novel start mode of operation which allows one channel to provide power to the other channel, thereby avoiding inefficient multiple converter operation and potentially faulty power buses. The bus configuration provides for coupling a first motor/generator to a second motor/generator via a first converter to thereby allow th first motor/generator, operating as a generator, to supply variable frequency power to the first converter, the first converter supplying variable frequency power to the second motor/generator to operate the second motor/generator as a motor. A cross-start circuit is provided for selectively coupling the first channel to the second channel to allow power to be transferred between the first channel and the second channel is supplied to allow the novel start mode. The cross-start circuit completely decouples from the first and second channels when the cross-start circuit is electrically faulted, resulting in electrical isolation of the first and second channels from the fault thereby allowing continued operation of the first and second channels.

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Rockford, IL, United States of America

John W Diemer