The Power Company's Problem in the Electric Supply for Large Single-Phase Load

Abstract

The position taken by the power company is that it should be able to supply all needs of energy in the community whether for industrial, street railway or trunk railroad use. The power company must also be able to supply energy of uniform pressure whether single-phase, two-phase or three-phase, at whatever voltage best suits the consumer. These conditions are best met by polyphase generating units, and three-phase units are almost universally adopted on account of the economy in transmission which they permit. When the demand for single-plhase current is heavy enough to produce an unbalance, some means of balancing must be provided in order to prevent reduction in the output of the generator, and also to maintain uniform voltage on all phases. Three methods of balancing are discussed; first, by equipping the generator field with damping devices; second, by the use of a separate machine similar to the three-phase induction motor; third, by means of a synchronous phase-balancer consisting of a two-unit machine, one of which transfers energy between phases and the other balances the voltage. Correction for power factor on each individual large consumer's line is suggested.