GB332974A - Improvements relating to electric motor control gear - Google Patents

Abstract

332,974. Asquith, Ltd., W., and Eastwood, W. May 11, 1929. Controllers, drum; motor control systems.-The control of two or more motors A, B of which only one can run at a time is effected by a master drum switch C, E, E<1>, and a single set of contactors d, g, such as would be used for one motor only. The handle h<5> of the drum controller can be moved in an H-shaped slot so that by axial movement the contacts E, E<1> select the motor to be used, and thereafter a pivotal movement of the handle one way or the other selects the direction of rotation. After such selection the contact C energizes a relay coil F to close its contact f<1> and open its contact f<2>. Closure of contact f<1> causes enrgization of contactor coil D with resultant closing of main contacts d and opening of contact f. The relay, however, does not close its contacts f<2> immediately, because the rotor current through coil f<3> maintains energization of the relay until the rotor current has subsided, whereupon contacts f<2> reclose to energize contactor coil G and close the rotor resistance shorting contacts g, g<1>. In a modification the master drum also selects the speed of running of one of the motors which is, in this case, provided with a double wound stator. A locking lever j<1> and a switch in the control circuits can be provided so that the use of one of the motors can be prevented when desired.