Showing papers on "Dynamic braking published in 1968"
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08 Feb 196825 citations
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03 Oct 19686 citations
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01 Jul 1968TL;DR: In this article, a new solid-state automatic field control for the winch generator is proposed to maintain a constant tension in the trawl warp over a wide range of speeds, and the speeds of the trawler and winch are automatically co-ordinated at the completion of shooting.
Abstract: Although trawlers are generally equipped with a Ward Leonard electric drive for the trawl winch, hand-controlled mechanical winch brakes are still used during the operation of ‘shooting the net’. On modern stern trawlers, the winch brake has to absorb some 200hp, and heavy brake-lining wear has resulted. The paper, after considering the practical problems involved in dynamic braking for this application, describes a new solid-state automatic field control for the winch generator which meets these difficulties by maintaining a constant tension in the trawl warp over a wide range of speeds. A side product of the new scheme is that the speeds of the trawler and winch are automatically co-ordinated at the completion of shooting. Elimination of hand manipulation of the winch brakes paves the way to control the shooting operation from the wheel-house. The paper also describes the laboratory tests carried out with a model simulator to prove the scheme. The results obtained with the model are compared with a theoretical analysis of the system. Finally the paper discusses the problems posed by the need to make satisfactory provision for the acceptance of the regenerative braking power. Different propulsion-machinery arrangements influence the treatment of this problem, and the paper describes the adaption of the warp-tension control scheme to four of the major propulsion and winch-generator drives in current use.
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TL;DR: In this paper, a brief historical background to vacuum contactors development is given, and a low-tension plug braking vacuum contactor starter is discussed, along with a comparison between air and vacuum arc extinction.
Abstract: A brief historical background to vacuum contactors development is given. Comparisons are made between air and vacuum arc extinction, and a successful vacuum contactor design is described. Details of field experience are given. Particular reference is made to improvement in dynamic braking performance made on a 2300-volt rubber mill drive. Suggestions are made for further improvement, and a low-tension plug braking vacuum contactor starter is discussed.
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01 May 1968