GB191106611A - Improvements relating to Variable Speed Dynamos, such as those Employed for Train Lighting. - Google Patents

Abstract

6611. Electric and Ordnance Accessories Co., Etchells, J., and Price, E. W. March 16. [Cognate Application, 16,068/11.] Lighting systems; regulation, automatic systems and apparatus for. - The output of variable-speed dynamos, particularly those used in train-lighting systems, is regulated by means of two contacts c, c<1> connected in the shunt field circuit and normally held together by the plunger c<2> of a solenoid coil c<1> in series with the main dynamo circuit, and a resistance C<4> connected across the contacts and of such a value that, when the contacts are separated by the action of the solenoid, it sufficiently reduces the field excitation to keep the dynamo output within a predetermined limit. A condenser C<5> prevents sparking at the contacts The resistance C<4> may consist of a selenium cell normally illuminated by a lamp in series with the contacts. In a modification, two contacts carried by a bar operated by the solenoid plunger engage with two stationary contacts between which the resistance C<4> is connected, the mid-point of the resistance being connected to the bar. Initial regulation of the apparatus is obtained by means of an adjustable resistance connected in shunt with the coil C', or, mechanically, by adjusting the tension of the spring acting on the plunger C<2>. A voltage coil J<1>, Fig. 4, may assist the coil C<1>. The covers C<2>, J may be arranged side by side on a pivoted bar., In addition to, or instead of, the coil J<1>, a coil may be provided in series with the lamps and act in opposition to the coil C'. It may be connected up between the coil C' and the lamps, or directly between the dynamo and the lamps so that the current to the batteries only is controlled by the regulator. Specification 3238/11 is referred to.