Patent GB-157457-A (GB)
Title: Improvements in means for interrupting electric currents, particularly applicable to lightning arresters
IPC: H01H71/68
Filed: 1921-01-10
Abstract: 157,457. Schweitzer & Conrad, (Assignees of Schweitzer, E. 0.). June 21, 1918, [Convention date]. Electrolytic interrupters; mercury and other conducting liquid switches.-An electric current flowing through a liquid is interrupted by accumulating the vapour resulting in such a way as to displace a portion of the liquid from an electrode. The invention is applied particularly to lightning-arresters being used either alone or in conjunction with a horn gap and with or without an electrolytic-arrester. It is also stated to be applicable for other purposes. The device is arranged to reduce the power current before interruption takes place and resets itself so that repeated operations take place automatically if required to relieve the system to which it is applied. A graphite electrode 20 of pyramidal form is mounted in an adjustable rod 12 (which may be graduated) in a gas tight upper cap 16 on a tube 15 of insulating material. A graphite disc electrode 21 is secured within a lower cap 17. The tube is partially filled with liquid of a relatively low conductivity such as water with a small amount of conducting material in solution; the liquid may leave a film of oil upon its surface. The heat resulting from the passage of current through the liquid evolves vapours (with which may be mixed dissociation products) which are trapped in a chamber formed by the upper cap. A needle valve 31 controls the release of this vapour and the operation of the device, the capacity and rate of operation of which may, however, be varied by other means. Excessive formation of vapour depresses the liquid level, reducing the current and eventually breaking the circuit, the vapours tending to quench any are and the comparatively gradual reductions of current prior to rupture avoiding disturbance of the supply system. The liquid displaced is received in a chamber 39, which may be open to atmosphere, and provided with a valve 60, tubing connecting the two vessels. A separate heater in the chamber 39 may be used to maintain the sensitiveness of the device. Several of the devices described may be operated in series or parallel, the control valves being common to all in an arrangement described. Fig. 5 shows a number of devices arranged in series in one casing. Several cones of insulating material are disposed along a tube 51 having perforations near the top of the interior of each cone and a valve 49. Electrodes 54 with tapered lower ends are arranged through each cone as shown. Fig. 1 shows an interrupter arranged to work in conjunction with a horn gap 2 and an electrolyticarrester 3 of known type with charging resistance 9 and horn bridge 8; the three last may be dispensed with, however, and by working with the liquid level normally below the electrode 20, Fig. 3, the horn gap may be discarded also and the device connected directly to the line. The Specification as open to inspection under Sect. 91 (3) (a) stated that the heat or electrochemical effects of the current might be utilized. This subject-matter does not appear in the Specification as accepted.