This SAE Aerospace Information Report (AIR) considers the following major areas: 1. major components and their ratings, 2. selection criteria for optimum design balance for electrical systems, 3. effects of operating conditions and environment on both maintenance and life of components, and 4. trouble signals--their diagnosis and cure.

Electrical Systems Engineering is the modern concept of integrating load requirements with generator/alternator and battery capacity and regarding this electrical equipment as a complete system rather than a collection of independent units. The old adage "a chain is not stronger than its weakest link" is particularly valid for electrical circuits. So great care must be taken in selection of equipment and in considering the operating position and environment in which the equipment is expected to function.