GB482634A - A system of protection for liquid-insulated electrical apparatus - Google Patents

Abstract

482,634. Protective cut-out arrangements; fiuid-actuation of switches. BUCHHOLZ, M. Feb. 27, 1937, No. 5972. [Class 38 (v)] Liquid-insulated electrical apparatus incorporates protective means within a casing of the apparatus including a detector mechanically operated by gases or vapours. or air and also separate detector means responsive to changes in temperature, each of said protective means being adapted to operate signalling or switch devices. In Fig. 8, the chamber 22 is housed on the top of, and normally separated by a flap 24 from, the apparatus chamber, the flap being pivoted at 23 and carrying a switch tube 7. A thermal capsule 12, heated by a coil 26 in dependence on the load current in the apparatus, is adapted to raise the flap and as the flap is also raised by production of gas on fault in the apparatus, the response of the switch will be more rapid the greater is the load. Figs. 5, 6, 9 show forms in which the device is housed in the pipe between the apparatus and its expansion vessel, a float 5 being pivoted at 6 to respond to drop of liquid-level caused by gas-accumulation in the housing, and a float 2 being pivoted at 3 to respond to violent agitation in the liquid produced by gas-formation. In Fig. 6, the capsule 12 acts to depress the float 2 so that operation of the latter to close contact 14 is more rapid the greater the temperature of the liquid and, therefore, of the apparatus. In order to show which cause has produced operation, the capsule also operates a visual indicator comprising a fixed slotted disc 17 provided at the back with a movable disc 18 with horizontal coloured lines. In Fig. 5, the capsule 12 acts on a member 16 which is pivoted at 3 and after a given angular rotation engages the float and moves it against contact 14. In Fig. 9, one end of a bimetal spiral 8 is attached to the float and the other end carries a mercury switch 15. In another form, Fig. 7 (not shown), a capsule engages a slide valve in the pipe itself and so offers a larger passage to the liquid as the temperature increases, and at a given maximum temperature, the valve closes a relay circuit. The Specification refers also to the use of a battery of capsules, to acoustic signals, and to Specifications 273,701 and 293,705, [both in Class 38 (v)].