GB592003A - Improvements in electric transformers - Google Patents

Abstract

592,003. Phase changing. FOSTER TRANSFORMERS & SWITCHGEAR, Ltd., and COURTNEY, T. Oct. 18, 1944, No. 20109. [Class 38 (ii)] In a transformer arrangement for supplying a single-phase load from a three-phase supply, which is to remain substantially balanced and of unity power factor for given load conditions, the single-phase load is taken from the secondary winding (not shown) of a first inductor DE which, together with a second inductor, divided in two parts BF, EC, and a capacitor L, is connected to the three-phase supply_ terminals A, B, C, as shown in Fig. 1. The two parts of the second inductor are wound on the same core. Vectors Ic, Il, Ir represent the components of the currents taken from the three-phase supply by the capacitor L, the inductor BF, EC, and the single-phase load respectively, and the values of the capacitance and inductance are selected so that the threephase currents IA, IB, Ic are equal and in phase with the voltage. Tapping point F is selected so that vectors Ic and Il are perpendicular and angles EAC is equal to 45‹ - #2 where cos # is the single-phase load power factor. In an alternative arrangement, Fig. 2 _ (not shown), the first inductor is divided into two parts and the second is continuous and has a tapping point. In a further arrangement, Fig. 3 (not shown) the inductances are extended or provided with tappings so that the voltage across the condenser may be different from the line volts. Specification 573,283 is referred to.