GB403622A - Improvements in and relating to systems of electric motor control - Google Patents

Abstract

403,622. Control 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 12, 1932, No. 13730. Convention date, May 15, 1931. [Class 38 (iii).] Varying E.M.F.-In a Ward-Leonard system, a switch is frictionally operated by the motor to one of two circuit-closing limit positions, according to the direction of rotation to enable reverse excitation to be applied to the generator for compensating for the remanence when the former excitation has been removed. When a control switch g is moved to one of its extreme positions, one of the fields l, r of an exciter e is energized to supply the field of a Ward-Leonard generator s supplying a rudder'motor m, which runs in the appropriate direction. The motor frictionally operates a switch k to one of its extreme positions, so that when the switch g is restored to its central position to stop the motor m, the field of the exciter and, therefore, the generator is reversed, and the motor begins to run in the reverse direction. Directly it carries the switch k into the other extreme position, however, the generator field is again reversed, and soon the motor comes to rest with the switch k in its mid-position. The switch k has intermediate positions between the extreme and midpositions in which resistances ware included in the circuit. In a modification the central contacts of the switch g are omitted and a small reverse excitation, sufficient to compensate the residual magnetism, is provided by means of a circuit including resistance y, when the switch k is in either of its extreme positions.