GB198936A - Improvements in safety devices for electrical apparatus - Google Patents

Abstract

198,936. Buchholz, M. Aug. 5, 1922. Transformers.-A safety device for transformers and other electrical apparatus operating in an insulating liquid comprises a cut-out or alarm, the circuit to which is completed by the action of bubbles of gas formed in the insulating liquid upon the occurrence of abnormal conditions. The bubbles may be the result of sparking, or they may be released, when the temperature, of the insulating liquid rises from hollow vessels having openings closed by a fusible substance, and they may operate a contacting device in various ways. Fig. 3 shows a transformer c in a bath a. Any bubbles formed rise up a tube s, and cause a float r to descend and complete a circuit at k to the cut-out f. In a modification, the formation of the bubbles causes liquid to be ejected which falls into a cup at the end of a pivoted bar. In another modification a diaphragm in the wall of the vessel a is vibrated against two contacts in the circuit to an alarm. Fig. 6 shows a modification in which contacts k are closed on the formation of bubbles by the relative movement of a large and small float C and D respectively. Fig. 8 shows a modification in which bubbles are released from a vessel G by the melting of a plug K. The bubbles rise past a spark gap F and so allow the circuit to the cut-out f to be completed.