GB190224710A - Improvements in Electrical Measuring Instruments. - Google Patents

Abstract

24,710. Carolan, E. A., [General Electric Co.]. Nov. 11. Current meters.-In a movable coil instrument the directive torque is due to the poles of an electro magnet or permanent magnet acting on a saturated strip of iron. Two pairs of poles, energized by a single core, are used to make the meter astatic. Fig. 2 shows a section of the poles of the magnet and the armature. Two pairs of flat coils 17, 17<a> are mounted on aluminium discs 16 fixed to the vertical axle 8. On the same axle are bars 1, 2 coated with a thin layer of magnetic material, such as iron or nickel. There are two pairs of polepieces N, S and N', S<1>. The coils 17, 17<a> and the directive bars 1, 2 are thus influenced by similar magnetic fields. One pair of coils is connected to the terminals 10, 10<a> and the other to the terminals 11, 11<a>, by which arrangement the currents in two circuits may be compared. The pole-pieces N, N<1> and S, S<1> are connected to opposite ends of a straight core of an electro- or permanent magnet. The instrument may be used as a volt-meter resistance mounted in the case being switched into series with the armature coils.