GB113150A - Improvements in and relating to Electromagnetic Switches. - Google Patents

Abstract

113,150. British Thomson - Houston Co., (General Electric Co.). Feb. 15, 1917. Electro-magnetic switches.-A lock-out switch has a shunt winding 10 mounted on the upper limb 12 of a U-shaped magnet frame, the lower limb being in three parts comprising a short central main pole-piece 14 and two longer auxiliary pole-pieces 15, one on each side of the main pole-piece and spaced therefrom. The switch member 18 is pivoted at 19 to a yoke extension 13 of the upper limb, and its lower end, which is under the influence of the main pole-piece 14 across the gap 29, carries on a non-magnetic extension 25 an adjustable armature 26 co-operating with the bent-over ends of the U-shaped magnetic frame 28 of the series holding-out winding 11. The yoke 13 also carries, pivoted at 31, a non-magnetic member 30 having an extended auxiliary armature 32 adapted to bridge the auxiliary pole-pieces 15. When the windings are energized, the armature 32 bridges the pole-pieces and a shoulder on the member 30 engages a plunger 33 on an extension of the switch member 18 and compresses the spring 21 thereby tending to move the switch member to the closed position. The armature 32 in its attracted position serves as a pole-piece for the lower end of the switch member 18 and diverts some of the flux from the gap 29 so that the switch member is magnetically balanced between the main pole-piece 14 and the attracted armature 32 serving as a polepiece. In consequence, in the attracted position of the armature 32, the lower end of the switch member is independent of variations of the current in the shunt winding 10. The switch member is maintained in the open position by the holding-out winding 11 against the action of the spring 21 until the series current falls sufficiently to release the armature 26, whereupon the lower end of the switch member moves out of the balanced position, and, under the influence of the armature 32 acting as a pole-piece, the switch member is magnetically brought into the closed position. Instead of employing the spring 21. which serves also for the resilient mounting of the contact 20 on the switch member, to produce the closing tendency a separate adjustable spring 37, Fig. 6, located in a housing in the member 30<1> may be employed. Specifications 23544/14, 112,996, and 113,001 are referred to.