GB122057A - Improvements in or relating to Protecting Devices for Alternating Current Apparatus. - Google Patents

Abstract

122,057. Kuyser, J. A. Jan. 31, 1918. Protective arrangements.-For the protection of alternating-current apparatus against internal insulation faults between turns of the same winding the resulting unbalancing of the voltages in two series-connected parts of the winding is used to operate automatic cut-out devices. In one form, two potential transformers are connected across the two parts of each phase winding, the transformer secondaries being connected in opposition and the relays for the cut-outs inserted in the connexions. In another arrangement, shown in Fig. 1 applied to a star-connected generator. each phase is connected to a reactance or to a potential transformer, and equipotential points A<1>, B<1> for example, on the phase winding and on the reactance are interconnected either directly through a relay or through the primary of a transformer C', the secondary of which is connected to the relay D<1>. Where two similar machines are available, equipotential points on corresponding phase windings are interconnected through relays. In the arrangement shown in Fig. 4, in which each phase consists of two parallel circuits, equipotential points such as A, A' are interconnected through a transformer, the secondary of which operates the relay.