Patent GB-191009097-A (GB)
Title: Improvements in or relating to Controllers for Electric Motors.
IPC: H02P3/06
Filed: 1910-04-14
Granted: 1911-04-06
Abstract: 9097. Adams Manufacturing Co., [Cutler Hammer Manufacturing Co.]. April 14. Systems for continuous-current motors only; electric braking; safety devices.-An electric motor controller is provided with automatic means for slowing-down the motor, and means for automatically disconnecting the motor from circuit upon failure of the slowing-down means to operate. The controller is shown as provided for controlling a motor M operating a winding- drum 1. The drum 1 is connected by a cable 2 to a hoist 3. The motor M is provided with an armature A, a series field winding F, and a shunt field winding f. For controlling the direction of the current through the armature, pairs of reversing switches 7, 8 and 9, 10 are provided, each pair having operating windings in parallel. Resistances R, R<1>, R<2> in the circuit of the motor are controlled by switches 13, 14, 15 provided with windings 13<a>, 14<a>, 15<a> respectively. When the hoist is in the position shown, a switch 19 is held closed, the circuit from the line 33 through its operative winding 19<a> being closed by a limit switch 26 to the line 34. When the switch 36 is moved into engagement with the contact 37, a circuit is completed from the main line 33 through conductors 40, 41, the windings 11 of the switches 7, 8, conductors 43, 44 to the contact 29<a> of switch 26<a>, and by conductors 45, 46 to the line 34. Switches 7, 8 are thus closed, completing the motor circuit through the resistances R, R<1>, R<2>. A diverter circuit in parallel with the armature is closed through the resistance 23 and switch 19. A mechanical brake 32 is also lifted on completion of the motor circuit. As the hoist descends, the switch 25 is released, and then the switch 26, thus breaking the circuit through the winding 19<a>. The switch 19 opens, breaking the diverter circuit through the resistance 23, and causing the contact-bar 20 to fall on the contacts 21, completing a circuit through the winding 13<a> of the resistance switch 13, and across a secondary switch 8<a> operated with the switch 8. The switch 13 is closed, cutting out the resistance R, and closing a circuit through the winding of the switch 14 controlling the resistance R<1>. The resistances R', R<2> are cut out in turn. The motor is thus brought up to normal speed. As the hoist approaches the lower limit, it engages the switch 26<a>, disengaging it from the contact 29<a>, and causing it to engage the contact 28<a>. This closes a circuit from the conductor 40 by the conductor 59, through the winding 19<a> and the conductors 60, 61 to the contact 28<a>, and thence to the conductor 46. The switch 19 is closed, and the circuit through the windings of the resistance switches 13, 14, 15 broken. The diverter resistance 23 is brought into parallel with the armature, and the resistances R, R', R<2> inserted, thus slowing down the motor. After the switch 26<a> has left the contact 29<a>, the current through the windings 11 passes through a maintaining circuit completed through the conductors 44, 62, switch 25<a>, conductors 63, 64, and switch 20 to the conductor 46. This maintaining circuit is only completed if the switch 19 closing the circuit for slowing down the motor is operated. If the switch 19 is not operated, the maintaining circuit through the windings 11 is broken at the switch 20, and the switches 7, 8 open, thus breaking the motor circuit and causing the brake 32 to be applied. If the switch 19 operates, the hoist descends at a slow pace until, on reaching the limit switch 25<a>, the maintaining circuit for the windings 11 is broken, thus opening the motor circuit and causing the application of the brake 32.