GB580150A - Improvements in electro-magnetically operated switches - Google Patents

Abstract

580,150. Electromagnetic switches; controlling motors. ELECTRICAL APPARATUS CO., Ltd., WALTON, J. R., and BARBOUR, R. H. June 6, 1944, No. 10847. Classes 38 (iii) and 38 (v)] An electromagnetic switch, particularly adapted to act as a star delta starter for an electric motor, has a member 24 biassed towards a neutral position, actuated upwards from this position to establish a circuit connection when an electromagnet 10 is energized, and adapted to return past its neutral position when the electromagnet 10 is de-energized. so that on the next energization of the magnet, the member 24 is moved downwards to establish a different circuit connection. The magnet 10 attracts an armature 11 which actuates a bell crank lever 14 the arm 20 of which carries a wedge 21 adapted to engage either below or above a wedge 23 on the member 24 which is pivoted on links 27, 30 and centralized by a spring 32. A bar 40 also moves up and down with the member 24 and carries cams which engage rollers on the ends of spring-biassed contact members. In the application to a star delta starter, Fig. 1, depression of a start button X completes the circuit to the magnet 10 which thereupon moves the members 24, 40 upwards so that contacts P, Q, R connect the supply L@, L2, L, to the ends A<2>, B<2>, C<2> of the three motor windings while contacts N, O connect the other ends of the motor windings producing the star arrangement. A contact M also completes a maintaining circuit and a control J completes a circuit through a secondary winding E and a thermal relay F. After a time interval the latter operates moving an arm G into engagement with a contact 3 breaking the maintaining circuit so that the magnet 10 is de-energized. The members 24, 40 move downwards past the neutral position and a cam H, closes at H a circuit re-energizing the magnet 10 but as the wedge 23 is now in its dotted position, Fig. 5 the member 24 is now moved downwards still further and completes at PQRSTU the delta connection for the motor. A maintaining circuit is also established through K. To return to the "off" position a delayed action stop switch such as described in Specification 577,372 is actuated. If it is desired to switch the motor in star only, as when inching, an "inching" switch may be used which interrupts the circuits through M E and F and so prevents the automatic change over from star to delta.