GB191400299A - Improved Devices for Braking Alternating Current Commutator Motors. - Google Patents

Abstract

299. Siemens-Schuckertwerke. Jan. 4,1913, [Convention date]. Alternating-current com-. mutator machines.-In the regenerative braking of alternating-current commutator motors, the magnetic saturation of the motor or of an electromagnetic circuit connected therewith is increased automatically as the brushes are displaced from the motoring to the braking position. In one example, Fig. 1, the lever d for moving the brushes from the motoring position F into the braking position Br is coupled to, a hand-lever h, which at the same time actuates, a switch s to reduce the number of turns of the stator winding st, which is connected to the mains n. The turns of a transformer may. be.altered instead of the stator winding, or the increase in the magnetic saturation may be effected by increasing the voltage applied to the stator winding. In polyphase motors, switchcontacts b, c, f are used. in each phase. Alternatively, the magnetic reluctance of the machine or of a connected electro-magnetic circuit may be reduced, simultaneously with the brush-displacement. In braking crane motors which return power to the mains when the load is being lowered, the switch-contacts, may be actuated automatically by a friction device on the shaft of the machine. The invention may be applied to traction motors and to motors with single or double sets of brushes: