GB254455A - Electro-magnetic switches - Google Patents

Abstract

254,455. Railing, A. H., and Angold, A. E. May 7, 1925. Automatic circuitbreakers in which the contact - member is moved in two stages to the closed position by the joint action of a closing and a maintaining electromagnet have the contact arm 4 pivoted at 5 to a member 3 on a fixed pivot 2, the arm 4 being provided with a spring 11 for biassing it towards the off position, and the member 3 being released after the the setting position is reached so that it does not hamper the opening movement. Normally as shown the back of the arm 4 rests against a fixed stop 21 but when the closing electromagnet 8 is energized the attraction of its armature 7 which is carried by the member 3 moves the arm 4 to the intermediate position, the crossmember 6 carried by the member 3 engaging the rear portion of the contact-arm 4. In this position the pivoted armature 13 carried pivotally at 14 by the arm 4 is brought against the holding electromagnet 16 so that if this electromagnet is now energized and the closing electromagnet de-energized the spring 11 moves the parts to the closed position in which the movable contact 15 engages the fixed contact 1. In this position the arm 4 is free to be released immediately the switch closes if faulty conditions exist in the controlled circuit, as in the final closing movement the driving portion 6 of the member 3 has been moved away from the rear of the contact arm 4. To facilitate any movement which may occur between the armature 13 and the pole-piece of the holding electromagnet 16 during the final portion of the closing movement the co-operating surfaces of these members may be slightly rounded. The member 3 may be provided with an arm 17 connected by a link to the piston of a single or double-acting dash pot which may be provided with an adjustable relief valve.