| 摘要 |
<p>403,290. Master control of A.C. motors. IGRANIC ELECTRIC CO., Ltd., 147, Queen Victoria Street, London.-(Assignees of Seeger, E. W.; 12th Street, Milwaukee, Wisconsin, U.S.A.) May 22, 1933, No. 14738. Convention date, May 20, 1932. [Class 38 (iii).] A motor 1 is plugged to rest by closure of a reverse contactor R, after a forward contactor F has been opened by opening of a stop pressbutton, the contactor R also being under the control of a relay 25 which during forward operation is mechanically latched by means 27, 28, but which is freed from its latch by closure of the contactor R, and remains under the control of a winding 30 connected in the rotor circuit of the motor, so that when the motor has slowed down or come to rest the relay 25 opens and de-energizes the contactor R to disconnect the motor. When an " inch " button is closed, the forward contactor F and a torque contactor T close, the latter shortcircuiting rotor resistances. The coil 30 closes the relay 25 with certainty and the relay is maintained by the mechanical latch. Upon release of the " inch " button the contactors FT open, and the contactor R closes to plug the motor and release the latch on the relay 25 which opens when the motor slows down or stops to de-energize the relay R and disconnect the motor. When a "Run" button is depressed the contactors F, T, and a relay 24 close, the latter maintaining itself and providing a circuit for the contactor F independently of the contactor T which opens when the "Run" button is released. Release of the " Run button causes a contactor S to close which shortcircuits rotor resistance to give a predetermined running speed, and also short-circuits the coil 30 of the relay 25. When a stop button is opened the relay 24 and contactors F, S, open, the contactor R being closed as a consequence, and plugging being effected under the control of the relay 25 as described in connection with the stopping of the inching operation. The relay 25 may have an additional winding connected in series with the winding 30 by closure of the contactor T to provide increased power for closing the relay, or it may be mechanically closed by closure of the contactor F.</p> |
