GB339661A - Improvements in and relating to alternating electric current measurement devices - Google Patents

Abstract

339,661. Ferranti, Ltd., and Holmes, W. Aug. 7, 1929. Transformers, - For measuring alternating currents, an ammeter a is combined with a transformer, the core of which is in two parts d, e, which can be separated so that the core can be placed around a conductor carrying the current to be measured. The portions d, e of the core are of L-shape and meet with butt joints, at b, c. The core portions are carried by members g, h hinged at i and having handles p, j by which they may be opened against the pressure of a spring k. At the contact faces b, c of the core, the section of the iron may be the same as that of the limbs, or may be greater in order to reduce the reluctance of the contact. To ensure correct bedding at the joints, the part d of the core is pivoted at m to a brass piece n secured to the member h, so as to permit slight movement about the pivot. The ammeter a may be of the moving-coil rectifier type and is connected to a secondary winding o carried by the part e of the core. The winding o may be tapped to provide different ranges of measurement, or several secondary windings of different numbers of turns may be provided, a switch being arranged to change the range. The aperture formed bv the core mav be insulated internally to facilitate manipulation around bare bus-bars.