Aircraft transformer-rectifier units

There is a need for a low-voltage d.c. supply in aircraft electrical systems; this is best provided from the a.c. system by means of transformer¿rectifier units since a separate d.c. generating system would impose a considerable weight penalty. The transformer-rectifier unit must be as small and as light as possible, yet it must operate within close performance limits. This article describesthe considerations relating to the design, construction and performance of such units