GB191117284A - Improvements in Automatic Electric Switches. - Google Patents

Abstract

17,284. Fagerlund, E. A. Aug. 8, 1910, [Convention date]. Electro - magnetic interrupters. - An automatic switch adapted for use in temporarily lighting staircases comprises a pivoted body with a relatively - movable member of magnetic material mounted thereon, the arrangement being such that the displacement of the movable member by a magnetic field alters the centre of gravity of the pivoted body and causes this to tilt, thereby closing an electric circuit which is opened after a predetermined interval by the damped return movement of the movable member. In the form shown in Fig. 1, the pivoted body comprises a solenoid a with a central closed tube c containing glycerine or other liquid in which the floating core d is mounted, the solenoid being provided with a contact-arm g which moves between fixed contacts h, i. The circuit of the solenoid is completed when the arm g makes contact with i; the core d being thereby attracted, the solenoid overbalances, thus breaking its own circuit at i and completing the lamp circuit at h. The core d is provided with a central channel f closed by a valve e and returns slowly to its lower position, when the solenoid tilts back again and breaks the lamp circuit. A permanent magnet k and armature l carried by the solenoid are provided to give a quick break. In a modification, Fig. 2, the contact-arm g is pivoted at w and provided with an armature o; when the solenoid is energized, the arm g is attracted and is held by a catch n carried by the solenoid, until the descent of the core d causes the solenoid to return to its original position, whereupon the catch n registers with a hole p in the contactarm g and allows the arm to drop. The solenoid may be fixed, the tube c being pivotally mounted within it, and the core d may be provided with an extension of non - magnetic material.