GB763708A - Improvements in and relating to reversible electric motor control means - Google Patents

Abstract

763,708. Control of A.C. motors. GENERAL ELECTRIC CO. Jan 14, 1955 [Jan. 18, 1954], No. 1242/55. Class 38(3) A reversible split-phase induction motor has field windings 3, 4, each of which may be used alternatively as a starting and running winding, and a squirrel cage rotor 2 which is coupled to centrifugal mechanism 7 having an arm adapted to separate contacts 9, 10. A friction device 11 is operated by rotor 2 to cause a switch-actuating member 12 to pivot in either direction in accordance with the direction of rotation of the rotor. When reversing switch 16 is in engagement with terminal 17, the main winding circuit is completed through contacts 20, 21, and winding 4, the starting winding circuit being made through contacts 9, 10, capacitor 34, and winding 3. At a predetermined speed, the member 12 pivots to open contacts 27, 28, without immediate effect, and, at a higher speed, contacts 9, 10, are separated to disconnect the starting winding. In order to reverse the motor, switch 16 is moved to engage terminal 18 so that the motor is disconnected from the supply and decelerates. When the speed has dropped to a given value, the contacts 9, 10, re-engage but the connections for reverse rotation are not completed until member 12 is biased back to its horizontal position and contacts 27, 28, re-close. In another arrangement, Fig. 2 (not shown), a relay energized in accordance with the motor current is adapted to close a series braking circuit including the two windings of the motor and the capacitor when the motor is disconnected from the supply.