GB741955A - Improvements in or relating to control systems for electric motors - Google Patents

Abstract

741,955. Automatic speed control systems. GENERAL ELECTRIC CO., Ltd., FRIEDLANDER, E. S., and MAER, C. A. April 14, 1954 [April 16, 1953], No. 10435/53. Class 38(4). [Also in Group XXXVII] A winder is driven by an induction motor 10 having a wound rotor, the stator being supplied with three-phase current through contacts 130 or 131 of main forward or reverse contactors respectively. Direct braking-current is fed to the stator through contacts 126 of a main braking contactor, the magnitude of this current, as well as that of the rotor resistance, being regulated as described in Specification 738,310. The main contactors have operating windings 53, 55, 69, and auxiliary contacts which provide interlocking to prevent simultaneous operation of two of these contactors. Pilot contactors having operating windings 163, 164, 165, control the main contactors, the pilot contactors for power operation being regulated by slider 45 coupled to speed-setting lever 40. Selection between driving and braking is effected by a polarized relay 72. When a pushbutton 167 is depressed, the pilot braking contactor is energized to open contacts 166 whereby the main power contactor which is then in operation is de-energized, after which the main braking contactor is closed. Thus a demand for dynamic braking operation supersedes a demand for driving. All the pilot contactors may be de-energized when a mechanical brake is applied, and the main contactors may be interlocked mechanically. Specification 717,253 also is referred to.