GB808567A - Improvements in or relating to distant control systems - Google Patents

Abstract

808,567. Electric selective signalling systems. GENERAL ELECTRIC CO. Ltd. Oct. 24, 1956 [Oct. 27, 1955], No. 30768/55. Class 40 (1). A distant control system in which a secondary member is arranged to be moved in response to movement of a primary member includes a multi-position switch of the make-before-break type arranged to be actuated by the primary member, a set of inductances connectible to a single-phase alternating current supply through the multi-position switch in such manner that for each position of the switch predetermined voltages are induced across the set of inductances and that movement of the switch from one position to another does not cause a shortcircuiting of the alternating current supply, and a resultant field apparatus having its rotor or stator connected to one set of inductances in such manner that the magnitude of the resultant magneto motive force produced in the rotor or stator is constant for all positions of the switch and the direction of the resultant magneto motive force varies with variation in the position of the switch and having its stator or rotor respectively connectible to a singlephase alternating current supply so that the secondary member which is mechanically connected to the rotor sets itself in a position corresponding to the position of the switch. A selsyn 7, Fig. 1, having a star-connected threewinding stator 9, 10, 11, Figs. 3a, 3b, is controlled by a 12-position switch 3, Fig. 1, which by differently connecting a single-phase A.C. voltage (terminals 18, 19) via three centretapped chokes 15, 16, 17, Figs. 3a, 3b (these Figures showing two of the 12 possible connecting arrangements) causes the rotor 8 of the selsyn-which carries a single winding fed with A.C. current-to assume 12 different positions. A development of the switch contacts is given in Fig. 2 (not shown), Figs. 3a and 3b corresponding respectively to switch positions 1 and 2. As shown in Fig. 1, the switch 3 is arranged to be driven either manually or by the motor through reduction gearing and the selsyn 7 is arranged to drive a multi-contact switch arrangement 5, also through appropriate reduction gearing. It is stated that the resultant magnetic field created by the stator in the selsyn is of substantially constant magnitude and that the windings could be delta-connected. Damping of any oscillations of the rotor of the selsyn can be effected either by a freely mounted flywheel and friction pads or by eddy current means.