GB349231A - Improvements in and relating to electric motor controllers - Google Patents

Abstract

349,231. Master control of motors. IGRANIC ELECTRIC CO., Ltd., 147, Queen Victoria Street, London.-(Cutler- Hammer Manufacturing Co.; Milwaukee, Wisconsin, U.S.A.) April 9, 1930, No. 11286. [Class 38 (iii).] Travelling between predetermined limits; continuous reversals.-A motor 4 for driving a skip hoist or like apparatus between limits is controlled so that it is brought to rest at each limit, and reversed after a time interval by means of a single relay. With loading at the lower limit completed, a pushbutton 8 is depressed energizing the coil 6a of a switch 6 which maintains itself closed over contacts 6b. Thus coils 5a, 12a are energized, the former closing a switch 5 and starting the motor, and the latter holding the contact arm 12b of a switch 12 above its contacts 12c. On reaching the upper limit, switches 9a, 9b are opened, and a switch 13 closed, by a member 17 travelling on a screw 18, so that the coil 6a is de-energized and the switch 6 opens to de-energize coils 5a, 12a, and so open the main switch 5, and stop the motor. The de-energization of the coil 12a allows the contact arm 12b to fall and after a time interval, determined by a dashpot 12d to bridge the contacts 12c, and switches 11a, 11b having closed at the beginning of the upward movement, the coil 7a of a switch 7 is energized. The switch 7 closes and maintains itself closed energizing coils 12a, 5a so that switch 5 closes again, and the motor is reversed, the switch arm 12b being again held above its contacts 12c. By similar operations the motor is stopped at the lower limit and reversed after a time interval. The switch 15 is a stop press button switch and the switch 16 is opened to prevent the automatic reversal of the motor when the bucket is required to stop in its loading position. A pushbutton 10 serves to start the motor in its bucket lowering direction. Under no-voltage conditions in the motor circuit the control circuits are rendered ineffective.