Improvements in or relating to ward-leonard control systems

摘要

415,568. Control of D.C. motors. RHEINISCHE METALLWAAREN - UND MASCHINENFABRIK, 195, Ulmenstrasse, Derendorf, D³sseldorf, Germany. July 24, 1933, Nos. 20830 and 20831. Convention dates, Jan. 14 and Jan. 20. [Class 38 (iii).] Varying E.M.F.-The excitation of the generator L of a Ward Leonard system is regulated by means of a counter-voltage machine D driven by a shunt machine A which is switched on simultaneously with the excitation so as to ensure strong starting torque of the working motor R when regulated for low speeds. In the arrangement shown, regulation is effected by control of the excitation of the machine D by means of opposed field windings d1, d2 and a resistance s, whereby the machine may either oppose or boost the line voltage. In order to prevent instability at low speeds, the excitation circuit of the generator L may include part of resistance S, or an additional winding connected to the brushes of machine D may be provided on the field of the generator L, so that the opposing voltage of machine D is not brought near to the line voltage. The machine D may be constantly excited and its voltage regulated by brushshifting. The switches s1, s2 may be constructed so as to connect machines A and D across field windings on the generator L when in the " off " position, so as to destroy remanent magnetism in machine L during the slowing down of machines A and D. Fluctuation of speed with load of the working motor may be counteracted by providing a supplementary field winding on machine D, connected across a lead connecting the armatures of machines L R.