Patent GB-191317899-A (GB)
Title: Improvements in Electric Switch Gear.
Inventor: HIRST JOHN ARTHUR
IPC: H01H21/06
Filed: 1914-03-06
Granted: 1915-04-22
Abstract: 17,899. Hirst, J. A., and Brook, P. S. March 6, 1914. Mechanically - interconnected switches; switch mechanism interlocking with lids.- Electric switch gear for use in collieries is enclosed in a casing divided into a main compartment, provided with an access door and containing the main switch and such portions of its operating and controlling gear as require to be accessible, and an auxiliary compartment which contains the ' live ' circuit terminals. An isolating-switch, operated by an external handle and adapted to cut off all parts in the main compartment from the live terminals, is electrically or mechanically connected to the main switch in such a manner that the main switch is opened during the initial movement to open the isolating-switch and before the latter switch is opened. The isolating-switch is provided with a locking-piece which locks the access door to the main compartment closed when the isolating-switch is closed, the locking- piece being provided with a detent controlled by the movement of the door and serving, when the door is open, to retain the isolating-switch in its open position. In the form shown in Fig. 2, the upper main compartment B is separated from the lower auxiliary compartment C by a partition D', a portion D of which is adapted to slide on rods fixed to the side of the casing and carries the movable parts E of the isolating-switch. The isolating-switch is actuated by an external handle H through links J, j<1> and connects the live mains g<1> in the compartment C to the terminals F of the main switch K, which is electro-magnetically actuated. The sliding partition carries also a bridge contact which, when the isolating-switch is closed, serves to bridge ' two spring-pressed contacts in the actuating-circuit of the electromagnet k'. In the closed position of the isolating-switch, a locking-piece P connected with the handle H engages with a slotted bracket Q on the closed hinged door B<1> of the main compartment. In order to open the door B<1>, the isolating-switch must first be brought to the ' off ' position. In this movement, before the contact-members E leave the fixed contacts F, G, the sliding bridge contact breaks the operating-circuit of the main switch, which consequently assumes the ' off ' position before the isolating-switch is opened. The door B' can then be opened, and a detent T drops into engagement with a tooth p' on the locking- piece to prevent the isolating-switch from being closed while the door is open. A pin R on the door releases the detent when the door is closed. In the form shown in Fig. 7, a portion D<2> of the partition is hinged at h<2> and carries the isolating-switch E', which is operated by an external handle as before and is connected bv the flexible strap e' to the terminals of an electro-magnetic main switch K, the actuating- circuit of which is broken at contacts k<3> by the member M<1> before the isolating-switch is fully opened. A pin P<1> on the hinged portion engages a slotted bracket Q' on the door B' and prevents the door from being opened when the isolating-switch is closed. When the door is open, a detent T<1> engages the end of the partition, as shown, and prevents the isolating- switch from being closed until the door is closed. In the form shown in Fig. 8, the main switch K<2> is operated mechanically by a handle on the shaft h<1>. It is separated from the isolating-switch by a fixed partition D', and is connected mechanically to the isolating- switch, located completely within the auxiliary compartment, by links n<2>, N, n', and the links are so arranged that the circuit at the main switch is broken before the isolating-switch leaves its contacts. Interlocks with the door B' are provided as before. A construction is also described in which the isolating-switch, as shown in Fig. 8, is completely located below a fixed partition and is operated by links from a handle pivoted in the upper compartment, the main switch being, however, electro-magnetically operated. The casing may be made up of two super-imposed fixed casings.