GB256282A - Improvements in and relating to electrical cut-outs - Google Patents

Abstract

256,282. Bell, B., and Illingworth, W. H. Feb. 3, 1925. Mercury cut-outs. -In mercury-thread resettable cut-outs of the type described i n Specifications 159,917, 172,446 and 189,284, the reserve of mercury is contained in a compressible rubber reservoir 4 secured between the orificed core e of ceramic material and the lower end of the insulating casing c so that the mercury is in contact with the lower terminal cap a. The core fits tightly within the lower portion of the partitioned inner casing f of metal, a hole in the partition registering with the channel in the coil and communicating with an axial orifice in a metal valve-member 3 fixed to the upper terminal cap b. The upper chamber of the casing j contains mercury which connects with the upper cap through the metal valve but, according to the invention, in order to provide an additional path independent of the valve member, a contactmember with spring tongues 6 is secured to the upper cap by the shank of the valve-member and rubs upon the inner surface of the casing f. The mercury thread is renewed by depressing the knob d, whereupon the inner ends of the guide bolts d' depress the easing f and with it the core e, against the action of the spring 2 on the pin 1, so as to compress the rubber container and force mercury therefrom up the channel to complete the column. On releasing the knob, the inner end of the valve-member bears down again upon the partition. The valve is provided with a venting passage 3g communicating with a channel in the valve-member vented at 3h to the atmosphere. The valve-member prevents the gravitational return of the mercury after expulsion on overload and is formed with inclined passages 3d leading to an axial channel 3<c> and constituting with it a number of acute-angled edges or covers over which the mercury spills, and at the same time presenting on the upper surface a number of deflecting baffles to control the ejected mercury. The valve proper, with a tapered portion to constitute the weir, mav be a separate element screwing into the valve stem. In the case of small current cut-outs where a capillary duct is used and the mercury does not tend to run back under gravity, the valve formation is unneccessary and the inner extremity of the member 3 which does not bed upon the partition is formed to serve simply as a, deflecting baffle. In this form the spring tongues 6 form the sole electrical connection between the upper end of the mercury column and the upper terminal.