Improvements in or relating to Starting Devices for Alternating Current Induction-motors.

摘要

6957. Kallmann, M. March 27, 1908, [Convention date]. Alternating - current induction machines. - In induction motors, the rotor circuit is closed on itself through resistances V, Fig. 6, having a high positive temperature-coefficient, for instance, iron wire or bands, as described in Specification 16,292/05, [Class 38, Electricity, Regulating &c.], and, if necessary, also through ordinary resistances w, Fig. 4, having a small temperature - coefficient, for instance, nickeline, and the motor is started or stopped only by closing or opening the stator circuit, while the variation resistances are disconnected towards the end of the starting period automatically or by hand. The star or triangle connexions of the resistances may be used, aud the resistances w may be cut out by a switch e, Fig. 4, separate from the switch b, which cuts out the resistances V. In braking the motor by reversing, the stator connexions resistances are connected in the stator leads I, II, III, or the resistances V in the rotor circuit may be changed from the triangle to the star connexion, or protecting-resistances w of nickeline or other material having a small temperature-cofficient may be connected in series with the resistances V when the braking takes place. The resistances x may be of the same material as the resistances w or the resistances V. In place of the resistances w, resistances similar to the resistances V may be used, or several resistances V may be connected in parallel. The resistances V and also the additional resistances w may be shortcircuited in one or more steps by a centrifugal device or by electromagnetic devices preferably connected to the stator circuit as shown in Fig. 8. The electromagnetic relay Z is connected to an air, fluid, or other damping-device G or to a clockwork regulator. The relay Z completes the circuit of the relay E, which operates the switch Q to short-circuit the resistances V. When the switch Q is operated, the switch B closes and completes the circuit of the relay E across the stator, thereby cutting out the relay Z.