IDG, CSD, Generators
IDG – The purpose of the integrated drive generator (IDG) is to provide primary electric power for the aircraft electrical system by converting variable engine input speed to a constant output speed, which enables the generator portion of the IDG to produce alternating current (ac) electrical power.
CSD – The purpose of the constant speed drive unit (CSD) is to convert the varying speed of the aircraft engine to a constant speed so that the generator it drives will produce current at 400 hertz within narrow limits. There is on CSD for each engine on the aircraft. Each CSD is a mechanical transmission with hydraulic controls governing the rational speed of the generator. The transmission is capable of either adding to or subtracting from the speed received from the engine gearbox in order to provide constant output speed to keep the generator on frequency.
Generator – A self-excited, air-cooled, brush-less machine designed for use in aerospace applications to provide alternating current power for aircraft electrical systems. It consists of an exciter rotating armature, exciter stationary field, alternating current stationary armature, main rotating field, a three-phase full-wave rectifier bridge, and a capacitor. It is driven and held within the speed range by a constant speed transmission, which is in turn driven by the aircraft engine.