Protection of the airplane main bus

The large increase in installed power of the airplane electric system since just before World War II, and the greater dependence which is placed on it for safe operation of the airplane, have directed much thought to the subject of system protection. As a result of this, methods and equipment are now available for effective protection of the generator circuits up to the main bus. In most cases this protection makes use of the current-balance principle for detecting ground faults. Generator overvoltage protection usually is included also. Equipment for protection of load feeders has not kept pace, in general, with the growth of the system, and the subject of main bus protection practically has been neglected. Several means are available for increasing the safety of the main bus, but there is need for development of better bus protection methods and devices.