GB200842A - Improvements in and relating to electrical apparatus - Google Patents

Abstract

200,842. Measurement, Ltd., (Assignees of Compagnie pour la Fabrication des Compteurs et MatÚriel d'Usines Ó Gaz.). July 17, 1922, [Convention date]. Void [Published under Sect. 91 of the Act]. Cut-out arrangements of the Merz-Price type in which the currents in the sides or ends of electrical apparatus and feeders are balanced against one another by means of current transformers interconnected by pilot wires employ transformers the secondaries of which are per. manently shunted by a resistance, in order to reduce to a minimum the effect of inherent inequalities in such transformers which manifest themselves on heavy overload, and in order to enable the usual instrument transformers to be employed more reliably as the current transformers also. In the arrangement shown in Fig. 2 for ono end only of a feeder, the secondary t<1> of the current transformer is shunted by the resistance r<1> and an ammeter A and an overload relay B are included in the circuit. The terminals of the resistance are connected through a relay R<1> through pilot wires p<1>, p<2> to the terminals of the corresponding resistance at the other end, the interconnection being arranged for opposed voltages. In order to avoid the action of the capacity currents in the pilot wires on the relays, an inductance S, Fig. 3, is connected across the shunting resistance and a capacity C across the pilot wires. The connections for a star-star and star-delta main transformer are described also.