Basic design principles for A-C electric-power systems in large military aircraft

THE ELECTRIC LOADS of early aircraft were small and the electric systems resembled those commonly used in automobiles. As the design of aircraft progressed, however, additional demands upon the electric system exceeded the capacity of the 14-volt d-c system, and a 28-volt d-c system was developed. Continued increases in electrical demands were met by increased generator ratings and parallel operation of generators at 28 volts direct current. As loads and aircraft sizes increased, the 28-volt d-c system became increasingly heavy to the point where it was obvious that a more economical generating and distributing system would be required.