Patent GB-278119-A (GB)
Title: Improvements in and relating to electric switches
IPC: H02P1/26
Filed: 1926-07-22
Abstract: 278,119. Cox, F. B. July 22, 1926. Automatic circuit-breakers.-Relates to switch gear of the type comprising a primary and one or more secondary (e.g. switch actuating, or releasing) members operated thereby. The axes of the members are arranged parallel and adjacent and the members are interconnected by mechanism which, when the primary member is moved in one direction', gives the secondary a movement in the opposite direction to a position where it is retained by a releasable device. The primary member is connected to one or more secondary members by a spring which, when the movement is imparted to the said members, is stressed and rendered potential to move either or both of the members, which it connects back to the initial position. Figs. 1, 1B, 1C show the invention in its simplest form as applied to a connection-changing (for example, star-delta) motor starter A<1> combined with a loose-handle circuit-breaker B<1>. The primary and secondary members A<1>, B<1>, are mounted on axes a, band have co-operating extensions a<3>, b<3>, a spring C<1> tending to restore B<1> to its " off " position against a stop and A<1> into engagement with contacts a'. When A<1> is moved to engage the contacts a<2>, B<1> is also moved to engage contacts b<1>, thereby establishing the motor circuit at the contacts b<1> through the starting contacts a<2>. When A<1> is released, it makes the running connections at contacts a<1> and the member B<1> is held by a latch D<1> under control of a solenoid d<4> which may be of a no-volt or overhead device or a combination of both. The various contacts are assumed to comprise insulated parts 5, 6, Fig. 1C, which are connected by the respective members. By dispensing with contacts a<2>, the device can be made to function as a loose-handle breaker, making one pole at a time. Instead of the extensions a<3>, b<3> the actuation might be effected by means of gearing or linkage, with suitable lostmotion. Fig. 3B shows the running position of a modified form of the gear shown in Fig. 1, wherein the primary member A<3> is actuated by a loose-handle a<7> which first moves it to the starting position where it is latched and, on release, trips the latch to restore it to running position. In another form, the primary member moves the secondary contact member through a trip member, which is latched in the " on " position and on release impels the contact member into the " off " position. In the form shown in Fig. 4C a primary member actuates a circuitclosing member B<4> and a separate connection changing member B<4>, both of which are loose on the shaft b. The contacts a', b<1> are in series and form the breaker contacts, whereas those b<6>, b' are the running and starting contacts, respectively. When the member A<4> is moved clockwise, it moves member B<4> to close the contacts b<7> and by means of the lever a<10> it moves B<4> to close the contacts b<1>. The motor circuit is not however made until the member A<4> is released to close contacts a<1>, which is the starting position. The running position is effected by releasing the member B<4> by hand or operation of a time limit device, the contacts b‹ being thereby closed, whereas, on overload or failure of supply, the solenoid d<41> releases the member 8<11>. In the form shown in Fig. 7A, a loose-handle A<71> moves the switch member A<7> over to contacts a<1> and also a trip member F<7> into engagement with a solenoid d<10>. Movement of the member B<7> to the contacts b<1> establish the starting position, the solenoid d' being actuated to release that member and give the running position. On overload or failure of supply, the solenoid d<10> releases the member F' which impels the member A' into the " off " position. In the constructional embodiment shown in Figs. 8, 10, the primary member A carries two sets of contacts A<6>, A<61> on the shaft a, and the shaft b carries the switch member B<6> and, loosely, the trip member F <6>. When the shaft a is rotated by handle A, the member F<6> is moved by the parts a<3>, f<3> into engagement with the retaining device D<6>, while a pin f<1> engages a tail-piece b<8> on the shaft b and moves it into the position where it is held by the latch H engaging the part b<10>. The contacts B<6> engage those b<1> :n this position and the stator windings P, Q, R are connected at one end by the bar A<6>, thus giving the star or starting position. When the handle is released, the spring C<6> moves it back and connects the contacts A<61> to the windings, thus giving the delta or running position. On overload or failure of supply, the solenoid D<6> releases the member F<6> which trips the latch H and allows the spring C<6> to open the switch at contacts b<1>. Fuses may be incorporated in the switch between the contacts A<61>, B<6>, in such a position that they are not in circuit in the starting position.