Design of generating equipment for Electra turboprop aircraft

WITH the advent of the Electra turboprop aircraft, a new phase was introduced in the type of electric power generated and distributed on commercial aircraft. Previously to this time, nearly all commercial aircraft used a 28-volt d-c system. However, the requirement for higher rated systems and the requirement of the load equipment for a-c power resulted in the Electra using the 115/200-volt 3-phase Y-connected a-c system. Many models of military aircraft had already used a-c systems but the systems in production at that time mainly used rotating exciter generators with sensitive protection relays. At the time that the Electra design was initiated a static excitation system with magnetic amplifier controls and protection was under development. This system was developed in order to increase reliability and provide closer limits of system performance. This static excitation system has been applied to the Electra and this paper discusses its design features.