GB111723A - Improvements relating to the Control of Electric Motors. - Google Patents

Abstract

111,723. Slater, J. M. L. Dec. 12, 1916. Controllers, liquid; electric braking.-To prevent flashing over at the contacts of a liquid resistance used with an electric motor when the motor is stopped by the reversal of its current supply, the movement of the controller handle causes the insertion of an auxiliary resistance, or varies the electrodes of the liquid resistance The motor 1 is shown as a three-phase motor supplied through a reversing-switch 3 and controlled by a liquid resistance 5. Resistances 7 are connected between the motor secondary and the liquid resistance 5, and they are short circuited by the switches 8 when the coil 10 is energized. The motor operates a double-throw switch 14 through a friction clutch, and this switch is connected between the coil 10 and a switch 21 which is operated when the reversing-switch 3 is operated. When the motor is running forward, the contacts of the switch 21 occupy the position 1 and the switch 14 is in position to connect the contacts 13, 15. The coil 10 is therefore energized and the resistance 7 short-circuited. When the controller is moved to the reverse position to stop the motor, the contacts of the switch 21 are moved to position II. thus breaking the circuit of the coil 10 and putting the resistances 7 in circuit. In a modification, auxiliary electrodes are connected to and disconnected from the circuit by the action of the coil 10, or a separate liquid controller may be substituted for the first during stopping.