Patent GB-159478-A (GB)
Title: Improvements in and relating to automatic electric cut-outs
IPC: H01H71/18
Filed: 1921-02-25
Abstract: 159,478. Szaszovszky, O. Feb. 25, 1921. Automatic circuit-breakers &c.-In thermally released circuit-breakers in which the circuit is held closed by a locking lever moved upon overload by an expansion member to allow a spring to open the circuit, a resetting mechanism comprising a spring-controlled arm is adapted to engage a holding device on the pivot of one of the switch contacts so that the resetting mechanism cannot be actuated until the circuit-breaker has operated. A cut-out comprises a fixed spring-contact 2 and a pivoted elbow contactlever 4, 5 biassed by a spring to open the circuit at 1. A locking lever 7, 8 engages the arm 5 to maintain the circuit closed until an expansion member 9 shall have been sufficiently heated by the overload. The resetting mechanism comprises an arm 31 actuated by a press-pin 29 against a spring to engage and turn the lever 4 into circuit-closing position, a prolongation of the press button pressing back the contact spring 2 so that the circuit cannot be closed until the press-button has been released. A pawl 32, pivoted on the contact pivot 27 and spring-controlled, engages a notch in the end of the arm 31 when the cut-out is set, so that the press button cannot be operated. It is freed from the arm 31 only when the cut-out operates, a stop on the elbow lever 4, 5 then engaging it after a certain angular displacement, and lifting it free of the notch in the lever 31. To avoid the effect of temperature variations the pivot 27 is mounted on the free end of a support 26 material of the same co-efficient of expansion as the lever arm 5. The Specification as open to inspection under Sect. 91 (3) (a) contains also the following subjectmatter. A thermally-operated electric circuitbreaker, Fig. 1 (Cancelled) comprises contact springs 1, 2 in series with a heating body 14 inside a tubular expansion member 9. The last is supported within a tubular or yoke member 11, of large section co avoid heating, having an adjustable abutment 10 and a screw 22 for current setting and for positioning the expansion member. The member 11 is supported in a block 13 fixed to an insulating base and a two-armed lever 7, 8 is pivoted in the block 13 and its arm 8 engaged by the expansion member 9. The cut-out is reset by a press-button 24 in the side of the casing of the device which operates upon a lever which normally maintains the circuit closed. One arm 4 of this lever presses the contacts 1, 2 together whilst it is retained in operative position by the engagement of its arm 5 with the lever arm 7. The push button is connected by a rod 25 to the contact spring 2 so that when resetting the circuit is not closed until the button is released and the apparatus properly set. A fuse 15 may be included in the circuit of the device. The supporting member 11 and preferably the lever 7, 8 also are made of material the co-efficient of expansion of which is the same as that of the expansion member 9 so as to avoid the effect of external temperature variations. This subject-matter does not appear in the Specification as accepted.