GB643434A - Improvements in or relating to electrical measuring apparatus - Google Patents

Abstract

643,434. Energy and quantity meters. SANGAMO WESTON, Ltd. Sept. 20, 1948, No. 24624. [Class 37] An. electric current to be integrated with respect to time is applied at t1, t2, Fig. 1, to energize winding M which causes pointer P to move at a speed proportional to the applied current ; the pointer oscillates between contacts Cl, C2 to actuate relay A which changes over the contacts a2, a3 to reverse the current through M and actuates a counter at contacts a5; according to the invention, electromagnetic means reinforce. the contact pressure between P and C1, C2, the electromagnetic means being energized in unison with the reversal of the current through M. As shown in Fig. 1, windings B1, B2 act as electromagnets to attract P and are energized sequentially by relay A ; relay A is actuated when P contacts C1 and released when P contacts C2, so that the counter is operated once for an oscillation of P from C2 to C1 to C2. As shown in Fig. 2, pointer P is moved by winding M1 and when contact is made with x or y, winding M2 is energized in the appropriate direction to urge pointer P towards the contact ; relays A or B are thus energized to actuate the counter D and to energize or de-energize relay C which reverses the contacts c4, c5, and operates contacts c1, c2 to locate the circuit of winding M2. Finally, as shown in Fig. 3, when contact P reaches x or y, the resistance R3 is put in circuit to add to .the current through M1 and thus reinforce the contact pressure; resistance R3 is removed from circuit at C2 or C1 when relay C is actuated or released. In both Figs. 2 and 3, the counter is operated for each swing of P from x to y or y to x. Specifications 538,160 and 629,716 are referred to.