GB542248A - Improved speed control system for a multi-engine power plant for the electric propulsion of moving craft - Google Patents

Abstract

542,248. Transmitting mechanical power ; automatic control systems for prime movers; governors. BRITISH THOMSON-HOUSTON CO., Ltd., JEWITT, D. E., and CALDERWOOD, J. July 15, 1940, No. 11707. Drawings to Specification. [Class 38 (iv)] [Also in Group XXVI] Speed control.-A number of A.C. generators supplying current to one or more motors driving a moving craft are jointly controlled in speed by an auxiliary A.C. generator and the speed of the auxiliary machine is made dependent on load variations to produce a drooping load-speed characteristic of the plant. The fuel admission valve of each of the prime movers is adjusted by a differential A.C. dynamo-electric machine one element being energized by the output of its generator or of a generator driven by the same prime mover and the other element being energized from the auxiliary A.C. generator, which is preferably driven by a D.C. motor with adjustable excitation. A further differential A.C. dynamo-electric machine energized from the output of the main generators and from the auxiliary A.C. generator adjusts a field rheostat of the D.C. motor to cause its speed to fall off when the loading produces a fall in frequency in the main generators. Excessive speed of each generator is prevented by a centrifugal governor operating through a lost motion on linkage connecting its differential machine with the admission valve to cause it to close. Each valve is adjustably coupled to its differential machine to determine individual loading of the main generators.