A constant-frequency a.c. system for aircraft

The increasing demands for electrical power in modern aircraft, and in particular 400 c/s constant-frequency supplies for various consuming devices, have emphasized the need for an electrical system which can provide the requisite amount of power for the lightest weight, the minimum maintenance and the maximum reliability. The constant-frequency a.c. system can satisfy these demands and meet the arduous conditions imposed upon it far better than any other system. The high efficiency, inherent robustness and reliability of the static transformer and induction motor contribute in large measure to the superiority of the constant-frequency system, and a further consideration is that it eases the problems associated with switching at high altitude.Methods of obtaining emergency supplies for vital services in the event of failure of the main alternators are described, together with various alternative systems of starting the main engines.The paper illustrates a typical aircraft installation and analyses the total weight; it also discusses secondary supplies, and equipment employed in the installation.