Patent GB-286051-A (GB)
Title: Improvements in or relating to electric switches and switchgear
IPC: H01H71/52
Filed: 1927-01-20
Abstract: 286,051. Cox, F. B. Jan. 20, 1927. Automatic circuitbreakers. - In switchgear of the type described in Specification 264,552 in which a switch part is held directly or indirectly in its contact closing position in opposition to a spring or gravity by a detent, toggle or like retaining device which is released by a percussive member controlled by a no-volt or overload coil, the percussive member constitutes the handle or operating part for retaining the switch member to its retained position after release. As shown in Fig. 1 the member A when released by the no-volt retaining magnet D falls and strikes the retaining detent C so permitting the switch arm B to be moved by the spring b3 to the " off " position. The member D may alternatively be held in its set position by a spring-controlled latch which is tripped by an overload coil which may be fitted with a suitable time-limit device. Alternatively as shown in Fig. 6 a separate switch arm E6 may be provided controlled by an overload coil o6 and bridging contacts e1 in series with the contacts b1. The arm E6 is moved to its retained position during the releasing movement of the spring-controlled percussive member A6, Fig. 6A, so that, in reclosing, the apparatus functions as a loose-handle circuit-breaker. In the modification shown in Fig. 8 the overload coil 08 acts upon a detent K8 latching the switch arm B8 to an intermediate member H8 which is retained by a detent C8 adapted to be tripped by the percussive member A8. In a further modification (Fig. 13, not shown) the switch arm is connected to the latched intermediate member by a spring which crosses a dead centre position during its operating movement. The overload coil in the form shown in Fig. 14 acts upon a retaining device for the switch arm B14 in the form of a toggle T1, T2 which may be collapsed either by the core of the overload coil 014 or by the percussive member A14 striking a projection t6 of the upper link T2. When employed as a motor controller the switch arm in moving to its retained position may wipe over one or a number of contacts corresponding to a starting connection or to a number of sections of a sparking resistance. Alternatively the switch arm while in its released position closes contacts corresponding to a starting connection or as shown in Fig. , 3 the switch arm may be biassed to a position midway between these contacts, being moved by the member A3 to the lower or starting contact before changing to the retained position in which it completes the running connection. In the arrangement shown in Fig. 7 which is similar to that described with reference to Fig. 6 the starting connection is completed through contacts b1 and e2 in series, the blade E7 being moved by a spring to its dotted position to complete the running connections after release by a time limit or current-responsive device. When the switches are enclosed in casings the operating arms are secured on shafts passing through the sides of the casing, the movable contacts being secured on a sleeve or sleeves surrounding the shaft and extending through one or both sides of the casing, actuating and tripping mechanism being provided between the externally-projecting ends of the shafts and sleeves.