GB373979A - An improved combined current and voltage measuring transformer - Google Patents

Abstract

373,979. Transformers. KOCH & STERZEL AKT.-GES., 40, Zwickauerstrasse, Dresden, Germany. Nov. 27, 1930, No. 35755. Convention date, Dec. 16, 1929. Void [Published under Sect. 91 of the Acts]. [Class 38 (ii).] A current transformer is combined with a voltage transformer in a single structure in which the field systems of the two instruments are at right-angles to each other. In the Figure, the primary of the current transformer comprises a straight conductor 11 passing axially through or lying parallel to an iron core 12 surrounded by insulating material 14 forming a leading-in insulator. The core 12 is energized by the primary winding 13 of the voltage transformer connected between the conductor 11 and an earthed mounting 20, the winding being arranged within the insulation 14 to control the potential distribution therein. The secondary winding 17 of the voltage transformer surrounds the insulation 14 and is surrounded by a slotted ring core 18 carrying the secondary winding 19 of the current transformer. An alternative arrangement is described in which the primary of the current transformer is of loop form and is passed through two side-by-side insulators through which extend the two limbs of a closed core for the voltage transformer, the primary of which is in two parallel-connected halves, one in each insulator. Separate voltage secondaries are provided on each half. The core used for the current transformer is in this case of shell-type with the centre limb extending between the insulators and carrying the secondary winding thereon, short-circuited auxiliary windings being provided on the outer limbs.