GB971411A - - Google Patents

Abstract

971,411. Moving coil instruments. M. BAERMANN. Aug. 1, 1961, No. 27920/61. Heading G1Q. A magnet arrangement for a moving coil meter comprises concentrically disposed annular outer and inner polepieces 12, 18 respectively and a radially magnetised part annular permanent magnet 11 seated against the outer pole piece in such a manner as to form an air gap 17 with the inner polepiece, the air gap serving to receive the moving coil 19. In order to achieve a homogeneous air gap flux over an angular range of at least 250 degrees,bodies 14, 15 of permanent magnetic material are arranged in the free spaces between the ends of the main magnet and the connecting bar 13 between the outer and inner polepieces, these bodies being magnetised perpendicularly to the magnetisation direction of the main magnet and being so dimensioned that the strength of the magnetic field established by them at the ends of the main magnet amounts to approximately 10% of the strength of the field established by the main magnet. The mag netic bodies 14, 15 may be made of barium ferrite and can be of cylindrical form so that they may be rotatably mounted for adjustment (Fig. 2 not shown).