Patent GB-190420496-A (GB)
Title: Improvements in Time Consuming Mechanism for Operating Electric Cut-outs and other Devices.
Inventor: GARDNER JOHN
Filed: 1904-09-23
Granted: 1905-09-07
Abstract: 20,496. Gardner, J. Sept. 23. Relays.-Relates to mechanism comprising a movable part, the period of movement of which may be varied, and which is used to effect any desired operation at any desired time after a certain event or its continuance. As a timeelement for an electric cut-out &c., the device comprises a rotating magnetic disc, across the face of which is arranged a bar capable of moving axially to complete an actuating-circuit for the cut-out. To the bar is hinged on one side a magnet, and on the other side an electromagnet, each adapted, when of sufficient strength, to engage the disc sufficiently to be moved by it, and to move the circuit-closing bar with it, each magnet moving the bar in a different direction. The contact-rod h, Fig. 1, supported in brackets p, p<1>, has hinged upon it the magnets q, q<1>, which rest upon a slowlyrotating disc of magnetic metal ; or the magnets may be solid with the contact-rod, which then has slotted &c. bearings to permit the magnets to rise and fall. The magnet q<1> is a permanent magnet, q being an electromagnet which, when energized by a shunt current from the main circuit, is stronger than the magnet q<1>. The contact-rod h is maintained, when no current is passing through the electromagnet q, against a stop in the off position shown, the disc being rotated in the direction of the arrow 1. When the magnet q is energized owing to an overload in the circuit a, the pull of the permanent mignet is overcome, and the disc slips the electromagnet q along so as to move the rod into the engagement position with the contact k, where a local circuit b is completed to cause the cut-out d to operate. The movement of the rod h occupies a time interval predetermined by the distance through which the rod has to be moved, and by the rate of revolution of the disc. If the dangerous overload does not persist sufficiently long for this movement, the rod will be moved back to its original position. When the electromagnet q is de-energized owing to the termination of the overload, the permanent magnet is-the stronger, and, coming into action, moves the rod h out of contact. By moving the rod and its magnets, by means of the slide s and screw t, in a direction at right-angles to the axis of the rod, the ratio between the times occupied by the contact closing and opening movements may be changed. The permanent magnet may be replaced by any simple frictional clutch, the grip of which may be varied by the current. In a modification, Fig. 4, the movable part is replaced by a pivoted arm h hinged at h<1>, and included in the local circuit, the clutches q, q<1> being arranged above the rotating disc, as before. The arm h is moved in one direction or the other, according to which clutch has the stronger grip. The rod h may be mounted upon a slide as before, and both magnets may be electromagnets. The rotating disc may be a non- magnetic conductor, and may be acted on inductively, and time variation may be obtained by altering the speed of the disc or by adjusting the position of the contact k. Instead of the disc being constantly rotated, it may be rotated by a suitable electromagnetic device upon the occurrence of the overload, and the permanent magnet may be replaced by a weight, spring, &c.