Electric meter including pivoted mag- net rotor surrounded by continuous pole faces

Claim 1

AN ELECTRICAL METER-COMPRISING (A) A GENERALLY U-SHAPED CORE COMPRISING A SINGLE SHEET OF THIN, SOFT MAGNETIC MATERIAL, (B) AN ELECTRIC COIL MOUNTED ON ONE LEG OF SAID CORE FOR PRODUCING MAGNETIC FLUX THEREIN UPON ENERGIZATION OF SAID COIL, (C) SAID CORE HAVING A CIRCULAR APERTURE IN ONE LEG WITH A CONTINUOUS CIRCULAR WALL, SAID APERTURE EXTENDING ACROSS THE MAJOR PART OF THE WIDTH OF THE CORE WHEREBY TWO MAGNETICALLY SATURABLE PORTIONS OF THE CORE ARE DISPOSED AT EITHER SIDE OF THE APERTURE, (D) A PERMANENT MAGNET, MEANS PIVOTING SAID PERMANENT MAGNET IN SAID APERTURE, SAID MAGNET BEING POLARIZED IN THE PLANE OF SAID APERTURE, AND (E) MEANS FOR BIASING SAID MAGNET TOWARD A PRESELECTED ANGULAR POSITION RELATIVE TO SAID CORE, AND MEANS FOR ADJUSTING THE RELUCTANCE OF SAID CORE FOR CALIBRATING SAID METER.