GB514359A - Improvements in and relating to electric switches - Google Patents

Abstract

514,359. Gas - blast switchcs. BRITISH THOMSON-HOUSTON CO., Ltd. Jan 28, 1938, No. 2826. Void. Convention date, Jan. 28, 1937. [Class 38 (v)] In a gas-blast switch of the kind having mechanism arranged so as automatically on contact-separation to produce a compressed-gas supply from which a blast is directed on to the region between the contacts, the operation of the mechanism is controlled by electromagnetic means including a winding carrying all or part of the current passing through the switch, either continuously or only when the contacts are separated, the winding being so arranged that the energy utilized by the mechanism is derived wholly or partly from said current. In Fig. I, opening movement of contact 4 actuates a locking system which releases a piston 2 of magnetic material, so allowing the stressed spring 6 to move the piston from the left and a 'cylinder 1 into the field of the continuously-energized winding 5, which drives it further to the right and forces a blast of air past (and through, @if desired) the fixed contact 3. Winding 5 may alternatively act on a core on the remote end of the piston rod, Fig. 2 (not shown). In Fig. 4, the piston 2 is fixed and the cylinder 1 is magnetic and movable by the winding 5 in co-operation with the fixed core member 19. The contact 3 is carried by, and moves with, the cylinder 1 so as to provide extra separation. In Figs. 5, 6 (not shown) an independent core acts on the cylinder 1 either directly, or through a spring, respectively, Fig. 7, shows a form in which the magnetic core comprises the piston 2 which is hollow and carries a tube 21 surrounding the movable contact A. This hollow-piston arrangement is also adaptable to a remote core which is connected either directly to the piston 2, Fig. 8 (not shown) or through a spring 14, Fig. 9 (not shown). Fig. 10 shows how the losses due to continuous energization of winding 5 can be avoided by connecting that winding in circuit at the moment of separation only. When closing the switch, contact 4 engages contact 3 and presses it back into engagement with an auxiliary short-circuiting contact 22 for the winding 5, which auxiliary contact is first disengaged on opening circuit. The cylinder 1 is magnetic and carries the contact 3, a spring similar 'to 6 being also fitted. The contacts 3, 22 may, alternatively, be in the form of rings traversed by 4, Fig. 11 (not shown) and in a construction similar to that of Fig. 7, an auxiliary contact 22 engages in the closed position, a conducting part of piston 2 and disengages it in the initial opening movement, Figs. 12, 13 (not shown). The Specification refers also to the use of a short-circuited or main-current carrying winding instead of a magnet core for certain forms of the invention, and to the use with the gas of substances which by expansion produce deionizing gas or vapour.