GB765643A - Improvements in or relating to electric contact convertors - Google Patents

Abstract

765,643. Converting; synchronous motors. SIEMENS-SCHUCKERTWERKE AKT.-GES. March 25, 1955 [March 27, 1954], No. 8845/55. Classes 35 and 38 (2). In an electric contact converter whose contacts are actuated by a synchronous motor the instant of opening of the contacts is regulated, e.g. kept at the centre of the spring step, by applying a signal derived from a winding on a switching choke, Fig. 1 (not shown) to an amplifier 16 the D.C. output iz from which is circulated in two exciting windings 12, 13 of the synchronous motor. This weakens and strengthens respectively the current i in windings 12, 13 which is derived from D.C. source 14 and passes also through exciting winding 11. Thus the effective magnetic axis and thereby the phase position of the rotor of the synchronous motor are changed so that the contact opening instant is varied by the signal. The angular range of operation is increased by the effect of resistor 18 in diverting current i through winding 12 with zero signal. Resistor 17 blocks amplified current from passing through source 14. When the exciter windings are on the stator the controlling and main circuits may be separated by connecting windings 11 and 13 in series respectively with separate subdivisions of winding 12, Fig. 4 (not shown). Control by varying the division of current between windings 12, 13 by means of a rheostat operated by a signal sensitive oil pressure regulator, Fig. 2 (not shown), is stated to be known.