GB699334A - Improvements in and relating to electric motor control - Google Patents

Abstract

699,334. Control of A.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 21, 1952 [Feb. 27, 1951], No. 4617/52. Class 38 (iii) When a split phase induction motor 1 is at a standstill and a two-way switch 16 is moved to engage contact 8, a field winding 2 of the motor is energised through coil 9 of relay 10, contact 14 of relay 13, and contact 23 of speedresponsive switch 22, the other field winding 3 of the motor being energised through capacitor 7 whereby the motor starts in one direction of rotation. The lifting of the relay 10 opens contact 15 to prevent operation of the relay 13, and engages contacts 32, 34, so that, when the motor speed reaches a predetermined value and the speed responsive switch 22 opens its contact, the winding 3 is disconnected but the winding 2 remains energised for normal running of the motor. Movement of the switch 16 to engage contact 11 causes the relay 10 to drop and the field windings of the motor are inter-connected through switches 27, 28, and the capacitor 7 for braking operation until the motor speed falls sufficiently to allow contact 23 to close. The field winding 3 is then energised through contact 15, coil 12, and contact 23, the field winding 2 being energised through capacitor 7 so that the motor is started in the reverse direction. When the centrifugal switch again opens, the energisation of the field winding 3 is maintained through contacts 33, 35.