GB404600A - Arrangement for voltage regulation and phase compensation in electric power lines - Google Patents

Abstract

404,600. Systems depending on static transformers. TELEFONAKTIEBOLAGET L. M. ERICSSON, 33, Kungsgatan, Stockholm. -(Assignees of Haal, A. S. ; 2, Herrgardsgatan, Vasteras, Jacobsson, F. M.; 66, Stavgardsgatan, Appelviken, and Lundholm, R. O. ; 12, Stenbocksvagen, Djursholm, all in Sweden.) April 13, 1932, No. 10623. Void [Abridged as open to inspection under Sect. 91 of the Acts, July 31, 1933]. [Class 38 (iv.] Protective arrangements. -Relates to an arrangement for effecting reactance compensation in a line L, Fig. 2, by coupling to the line a condenser C in which the overload voltage applied to the condenser is limited by the core P of the transformer saturating and consists in means for automatically short-circuiting a winding T on the occurrence in the core of a high saturation due to overload or short circuit so as to avoid undesirable saturation phenomena. Fig. 1 shows the currentvoltage curve of the transformer condenser combination, saturation of the core occurring at the point a. Since the curve has the loop a b c due to the magnetising current cancelling the capacity current instability occurs at a and as soon as the current exceeds the value Ia the voltage jumps to the upper part c e of the curve and it is necessary to reduce the current to the value Ib before saturation disappears. A relay K having an operating coil A energised from a current transformer in the secondary circuit short circuits a winding T through a maintaining coil H when saturation occurs, the maintaining coil holding the relay closed while the overload persists. In a modification for a three-phase line a star-connected secondary is connected to a star connected group of condensers the operating coil of the relay being connected to a transformer in the neutral lead. Specification states that the loop a b c may be removed by applying a resistance load when saturation occurs.