GB380085A - Improvements in and relating to electric motor control systems - Google Patents

Abstract

380,085. Maintaining proportional speeds of D.C. motors. INTERNATIONAL GENERAL ELECTRIC CO., Inc., 120, Broadway, New York, U.S.A.-(Assignees of Allgemeine Elektricitats-Ges. ; 2, Friedrich Karl-Ufer, Berlin.) May 30, 1931, No. 15874. Convention date, May 31, 1930. [Class 38 (iii).] Field control; varying E.M.F.-Several mechanically co-operating motors are connected to a common supply in series with auxiliary generators which have opposed series and separately excited fields and run at constant speed. A Ward-Leonard generator 1 supplies working motors 10, 11, 12 through generators 16, 17, 18 which are driven at approximately constant speed by a motor 19. The generators 17, 18 have opposed series and separately excited field windings, while the generator 16 is pure series wound. The generator 16 compensates for the voltage drop in the armature circuit of the motor 10 at all loads while the generators 17, 18 give zero voltage at half load and compensate for one-half of the voltage drop at full load. The motors 10, 11, 12 are maintained at proportional speeds by means of differential devices 7, 8, acting on field regulators 23, 24, 25. The devices 7, 8 are supplied with guide frequency from a source 9, and are driven through belts 6 and coned pulleys from the working motors. The regulators 24, 25 are shunted by resistances 28, 29 which are varied in accordance with the exciter control 5 of the Ward-Leonard set, so that the angular deviation of the regulators 24, 25 is independent of the motor speed at which a change of load occurs, and to prevent these regulators from operating upon a change of basic speed an additional resistance 30 is provided in series with the resistances 28, 29, and the regulators 24, 25, and is also adjusted in accordance with the exciter control 5, but in an opposite sense.