Flameproof converter drives for cable railway engines

It is state of the art to use hydrostatic power transmissions for cable railway drives in underground coal mining because of the need for good speed control. Their specific disadvantages, namely low efficiency and environmental risks with hydraulic fluids, can be eliminated by using flameproof converter drives. The paper examines three different concepts of converter-powered drives suitable for cable railway engines and compares these alternatives on the basis of their characteristic volumes, total efficiency, current consumption and the quality of the speed control. The comparison is based on the assumption that the drives are operated during representative load cycles that were gained by measurements on cable railways.