GB433141A - Improvements in or relating to electric protective arrangements - Google Patents

Abstract

433,141. Protective cut-out arrangements. ELECTRICAL IMPROVEMENTS, Ltd., Carliol House, Newcastle-on-Tyne, and GREGORY, R. W., Makendon, Causey Way, Hexham, Northumberland. Feb. 9, 1934, No. 4346. [Class 38 (v)] [See also Group XXXVI] An electric transmission or distribution system having an earthed neutral point is protected against transient earth faults by providing an automatically reclosing circuit-interrupting device in the neutral earthing connection, such device acting to break the connection and quickly remake it, on the occurrence of an earth fault. In the arrangement shown in Fig. 1, the neutral point A is connected to earth through a fuse C and switch arm D. In the event of an earth fault, the fuse blows and momentarily interrupts the circuit, which is immediately reclosed by the movement of the switch arm D on to a contact D<1> connected to the neutral point A. In an alternative arrangement, Fig. 2, a series of fuses C, E, G are successively brought into circuit by the release of switch arms D, F, a further switch arm-connecting the neutral point A directly to earth on the blowing of the last fuse G. A hand-operated switch J, which may be interlocked with the cover of the tank B containing the switches and fuses, is provided to enable the neutral point A to be earthed independently of the switches and fuses. In a modification, Fig. 5, the neutral point is earthed through a fuse K connected to a pivoted latch lever L which normally holds a second fuse M in an inoperative position. When the fuse K blows, the latch lever is released, and the fuse M drops into a position in which it bridges the gap in the circuit caused by the blowing of the fuse K.