GB772087A - Improvements relating to maximum-demand electricity measuring instruments - Google Patents

Abstract

772,087. Maximum demand indicators. FERRANTI, Ltd. July 6, 1955 [April 10, 1954], No. 10613/54. Class 106 (3). A maximum-demand instrument for indicating separately the maximum demand during two alternately occurring sub-assessment periods each of which consists of an integral number of successive demand integrating periods comprises a driving component 10, Fig. 1, rotated by the driving element of the instrument in dependence on the energy consumption during successive demand integrating periods and to be reset at the conclusion of each of such periods to a zero angular position common to all such periods, two pointers A, B, allocated one to each of the sub-assessment periods'traversing a scale 11<SP>11</SP>, and time-responsive coupling means for causing the driving component 10 during each of the sub-assessment periods to be in driving association with only the pointer allocated to that period. As shown, the coupling means comprises a driving arm 12 secured to the shaft 10 and extending radially therefrom and having two stable positions only, 14, 15, for its free end 13. In position 14 the arm 12 drivingly engates projection 31 of pointer A, and in position 15 projection 32 of pointer B. The arm 12 is transferred from position 14 to position 15 at the end of the sub-assessment period by means of a yoke 18 operated by an electrical relay. The arm 12, Fig. 3, is, at its inner end, formed of two rigid members 35 with projections 36 in knife-edge bearing engagement with notches cut in bearing members 34 of a cradle 33 secured to the shaft 10 so that the arm 12 is rotatable into two stable end positions about an axis 37 under action of a toggle-spring 38, the movement being limited by stops 43, 44.