GB1024838A - Improvements in integrating meters of the rotor disc type - Google Patents

Abstract

1,024,838. Induction meters. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. April 23, 1963 [May 11, 1962], No. 18249/62. Heading G1Q. In an integrating meter in which a rotor disc is provided on its upper surface at or near its periphery with at least one reference mark, a light re - flecting surface above the disc in the vicinity of a window in the meter casing returns light, originating from outside the casing and reflected by the disc away from the window, back towards the disc to improve its illumination. As shown, Fig. 2, the rotor disc 3 of an induction type watt-hour meter drives a counter 7 having display tumblers which are observable through a window 11 in the front wall of the meter casing 1. For calibration purposes the rotor 3 bears radial marks about its periphery, and a dial plate 19 has an extension 21 bent backwards along a horizontal line 22, so that light entering the window 11 is reflected by the preferably whitish surface of extension 21 to illuminate the part of the rotor nearest the window. A datum mark on dial plate 19 is continued on to extension 21, and casts its image on to the rotor disc; errors due to parallax are avoided by ensuring that the datum mark and its image are aligned, as in Fig. 3 (not shown). Fig. 7 (not shown) depicts an alternative arrangement in which the rotor is observable through an aperture 35 in a makers' nameplate; the reflecting surface is provided by a part 31 from aperture 35, bent backwards as shown. To improve illumination of the disc, the reflecting surface may be curved. The datum mark may be arrow-shaped.