GB718214A - Governor controlled electric motor - Google Patents

Abstract

718,214. Centrifugal switches; switches held set and freed mechanically. BRITISH THOMSONHOUSTON CO., Ltd. June 12, 1952 [June 14, 1951], No. 14843/52. Class 38(5) The combined " on-off " and centrifugal switch of Specification 675,390 is modified by mechanically connecting the contacts of the two switches to ensure that the centrifugal switch opens before the " on-off " switch so that the latter only interrupts the residual current through an impedance which is short-circuited when the centrifugal switch is closed. The centrifugal switch comprises a fixed contact 13 and a movable contact 12 fixed to a resilient member 26 and biased to close. The " on-off switch comprises contacts 14, 15 on resilient members 22, 23 respectively anchored to opposite legs of an insulating support 21, both members 22, 23 being biased to the left. Member 23 carries an insulating stop 32 co-operating with a conducting stop 31 on member 26 so as to limit movement of contact 12 to the right. The member 23 and a member 29 on which contact 13 is mounted are electrically connected by a rivet 25 so that the switches are in series. The circuit is closed by movement of pin 33 to the right, thereby closing contacts 14, 15. Further movement of spring 23 to the right permits similar movement of contact 12 until it engages contact 13. Return movement of pin 33 allows member 23, which is stronger than 26, to move to the left to separate contacts 12, 13, further movement of member 22 allowing contacts 14, 15 to open. A signal lamp may be connected in series with contacts 14. 15 across the supply. The stop 31 also acts as a cooling fin. Contacts 12, 13 may be controlled independently of the contacts 14, 15 by the speedresponsive mechanism.