GB296749A - Improvements in electrical measuring instruments - Google Patents

Abstract

296,749. Record, J. W. June 7,1927. Electromagnetic current and pressure meters with fixed and moving irons in the field of the coil are provided with two fixed tapering irons a, c. Fig. 1, extending around arcs on the interior and exterior respectively of the coil band with two moving irons d, e on the same spindle f carrying the pointer. The iron e extends over the edge and down the side of the coil b and is increasingly attracted by the iron c as the repulsion between the irons a, d decreases, the total defection being thus increased and the scale made more uniform. In a modification, Fig. 3, the iron e is omitted and the external fixed iron c is arranged on or extending over one or both edges of the coil to attract the iron d. The iron c may then comprise a strip across the coil and mav be extended as indicated in dotted lines. In other modifications, the repulsion couple may be produced on the outside of the coil. Specifications 177,757 and 290,738 are referred to. The Provisional Specification describes also modifications in which the external iron is adjustable and in which two fixed irons are arranged in different horizontal planes within the coil to operate with two moving irons.