GB606234A - Improvements in and relating to protective arrangements for liquid immersed electrical apparatus - Google Patents

Abstract

606,234. Protective cut-out arrangements. FRIES, E. Jan. 11, 1946, No. 1002. Convention date, Jan. 11, 1945. [Class 38 (v)] A protective arrangement for liquid - immersed current and voltage transformers or other electrical apparatus, particularly of low power and high voltage, comprises a float which operates a circuit-interrupter upon the formation of gases of decomposition due to a fault in the apparatus. The float 6 is mounted on a pivoted arm 11 connected to a slidable rod 10 which normally latches a contact arm 12 in the closed position. Upon gas rising to the top of tank 2, the float drops and lowers the rod 10 to trip the interrupterarm 12. In Fig. 2, the float acts additionally by means of an insulating rod 32 on a switch contact 33 in an indicating circuit, and the rod 10 carries a plate 35, in a hole in'the lid, which causes the interrupter to be opened on a sudden rush of gas. In a modification of Fig. 1, the rod 10 releases a spring which causes a weakened conductor to be broken, the conductor being fusible so as to rupture on overload and means being provided to extinguish the arc, Fig. 3 (not shown). In Fig. 4 (not shown), the arm 12 on opening inserts a limiting resistance in circuit, the resistance being cut out a little later by a second arm connected to arm 12 by a compression spring. The arm 12 may, alternatively, be bifurcated at its upper end so as to slide along a voltagedependent or other resistance during opening, Figs. 5, 5a (not shown). A fusible conductor may be mounted in the arm 12 which may support, or be wound with, a shunt resistance, Figs. 6-8 (not shown). An overload bimetal strip may be arranged to actuate the float to trip the interrupter, and where it is necessary that the circuit should not be interrupted, as in a current transformer, the rod 10 is arranged to short-circuit the supply to the apparatus before disconnecting it. The Specification as open to inspection under Sect. 91 also sets out an arrangement, Fig. 2 (Cancelled) (not shown), wherein the float is in the connection to the expansion vessel 4 and carries a mercury switch which, when tilted, energizes a coil to attract a rod 10, disposed externally of the insulator 8, to trip the switch. This subject-matter does not appear in the Specification as accepted.