GB609950A - Electric motor control systems - Google Patents

Abstract

609,950. Control of motors. IGRANIC ELECTRIC CO., Ltd. March 26, 1946, No. 9327. Convention date, March 26, 1945. [Class 38 (iii)] Travelling to predetermined limits.-An electric motor control system comprises a rotary drum, which, for example, forms part of a tyrobuilding machine, an electric motor for rotating said drum, reactor means including a part driven by said motor and moving in a fixed relation to said drum to vary the reluctance of said means for a varying reactance value attaining a maximum in a given rotary position of said drum, and control means rof effecting running of said motor and for effecting automatic stopping of said motor, said control means including relay means operated in response to a predetermined reactance value of said reactor means for initiating stopping of said motor. An electric motor M driving a drum D is stopped when a U-shaped member 1 of magnetic material, which is carried by an arm on the drum-shaft, straddles a stationary magnetic core 4 which is provided with a coil 5, thereby increasing the reactance of said coil to effect de-energization of a relay in the motor control circuit. Similar operation obtains when the member 1 coacts with a core 4a and coil 5a. The motor M; which may be of the directcurrent shunt-wound type, is supplied from the mains L1 and L2 through contacts of a switch 10 which also affords dynamic-braking through a resistor r. The coil of the switch 10 is supplied from alternating-current mains L3 and L4. Upon operation of a push-button switch 18 a relay 16 is closed to energize a relay 14, through contacts of a selector switch 19, and to close the main switch 10. Closure of the relay 16 short-circuits the coils 5 and 5a. The relay 14 closes a self-maintaining circuit independently to the relay 16 which is de-energized when the contact of a time-delay relay 17 opens. The release of relay 16 interrupts the short-circuit of the coil 5a to place it in series with the coil of the relay 14 which is released to open the main switch when the member 1 straddles the core 4a. When the selector switch 19 is moved to an alternative position, the reactor coil 5 and a relay 15 become effective. Additional stopping-positions of the motor may be provided. The selector switch may afford a wide variety of control-sequences.