GB368947A - Improvements in or relating to heavy-current electric switches - Google Patents

Abstract

368,947. Heavy-current switches. SIEMENS-SCHUCKERTWERKE A K T.- GES., Siemensstadt, Berlin. Feb. 14, 1931, No. 4731. Convention date, Feb. 15, 1930. [Class 38 (v).] Fluid-actuation; pneumatic blow-outs ; arcrupturing devices.-Circuit is opened by forcing an electrolytic switch liquid under pressure between the electrodes to cause relative movement between them, water (with or without added substances) being a suitable liquid. An increasing resistance is thus interposed in the circuit prior to the final break. In a simple form, liquid is forced between two electrodes slidable in a cylinder, to move them apart. In another form, a grid-like fixed electrode is located between a movable consistent electrode and a piston-like member, the latter being moved to force the liquid through the grid and so move the movable electrode. A development of the latter form is shown in Fig. 3 in the closed position. When the piston 21 is raised, it lifts the liquid-level 22 to trap gas in the space 26 and lift the part 28 so that the main movable electrode 24 leaves the fixed electrode 23. When the stop 29 arrests this movement, the part 31 and small electrode 25 are forced up the small cylinder 27 to make a further break, this movement being in turn arrested at the stop 32. Circuit is finally broken between the pin 33 and the contact 34 on the part 31. In the form shown in Fig. 5, one electrode 44 is a body of mercury above which is the liquid 40. The valve 39 is opened to admit air under pressure and then the valve 41 is opened, the mercury acquiring a certain velocity before the level 38 thereof leaves the fixed electrodes 37. By tapering the insulating vessel 42 the cross section of liquid 40 decreases with the switching- off time. The electrodes may, alternatively, be of a spongy material, or of powder or shot, and the liquid may be moved by pressure of its own vapour which pressure may be currentresponsive and may therefore depend for its magnitude on the current to be interrupted. The Specification as open to inspection under Sect. 91 (3) (a) states also that a circuit may be opened by separating contacts in a liquid flowing either along, or normal to, the direction of separation. This subject-matter does not appear in the Specification as accepted.