Patent GB-450453-A (GB)
Title: Improvements relating to electro-magnetically actuated relays and mechanisms with particular reference to electric switch actuation
IPC: H01H9/56
Filed: 1935-01-12
Abstract: 450,453. Protective cut-out arrangements ; electrically-tripped switches. BULLEN, A. G., 29, Newstead Road, Liverpool. Jan. 12, 1935, No. 1089. [Class 38 (v)] An electromagnet relay is arranged to have injected into its winding a unidirectional impulse of current per cycle, and a corresponding attraction of its armature or core imparts a succession of impulses to a movable member which, on being moved a predetermined distance by the succession of impulses, causes a switch mechanism to be released. The consuming apparatus 4 is connected over conductors 1, 2 to a remote A.C. supply A and its casing together with the metal conductor sheathing S is connected to a metal housing 5 containing the relay. An electromagnet 6 is connected through a rectifier 7 to casing 5 and also to earth 9. Its spring-controlled armature 10 (or a core) carries a tappet 11 which, on a leakage from the live conductor 2 to the sheath S or cooker occurring, so that the armature 10 vibrates in synchronism with the half-waves, rides up a lever 14 pivoted at 15, so removing a lug 16 from a bar 17 normally resting on knife edges 18. A spring-controlled arm 19 gradually pushes past a roller 20 on the bar 17 and opens a switch 22 to disconnect the apparatus 4 from the supply A. A low-impedance solenoid 24 connected to casing 5 over a rectifier 21a and to an earth pin 23 acts, when energized, to lift the left end of bar 17 and allow switch 22 to open, this solenoid being designed to prevent excess potentials on the apparatus when, due to rain, the earth resistance between 23 and the supply is too low to permit operation of electromagnet 6. The arrangement may, however, be substituted by a thermal device as described in Specification 406,333. In Fig. 2, an arm F pivoted at G carries a main contact B engaging a fixed contact A' and an auxiliary contact B<1> engaging a pair of contact strips C. The arm F is urged by a spring E in the opening direction, but is normally restrained by a part I thereon engaging a latch J<1>, the upper end of which carries an adjustable screw N engaging a spring-controlled bar L. A rack on the latter engages a pinion Q secured to a toothed wheel R co-operating with an escapement S<1> having a spring V<1> which causes the escapement to resist the pressure applied by I. An electromagnet W acting similarly to 6 in Fig. 1 causes a succession of impacts to be given to the escapement, whereby the wheel R is rotated clockwise until the parts I, J<1> are disengaged and the main circuit opened, the screw N being adjusted so that opening at current-zero occurs. The spring M restores the bar L to its initial position against stops P. The bar L is held in operative position by a roller Z controlled by a no-volt coil ZZ energized by the main circuit, voltage failure on which allows the bar to drop and the switch F to open. The switch F may alternatively be held on by the core of a contactor type solenoid under control of overload trip gear, operation of which de-energizes the solenoid and allows the weight of the plunger to pull the arm F " off."