Patent GB-911423-A (GB)
Title: Improvements in or relating to electricity meters
IPC: G01R11/60
Filed: 1961-04-24
Abstract: 911,423. Maximum demand meters. LANDIS & GYR A.G. April 24, 1961 [April 29, 1960], No. 14783/61. Class 106 (3). Maximum demand mechanism for electricity meters, in which the maximum value indicated is transmitted to a counter 19 simultaneously with the return to zero of the maximum demand pointer 8, comprises an actuating shaft 1 which can be driven by a motor 5 and can be connected through a first friction coupling 9 to a transmission shaft 2 for transmitting the indicated maximum value to the counter 19, the transmission shaft 2 in turn being able to be connected through a second friction coupling 10 to a resetting shaft 3 for returning the pointer 8 to zero, the first coupling 9 being connected to the shaft 1 through a third friction coupling 13 of smaller dynamic friction torque than the other two couplings, and a slide member 31 such that the shafts 1, 2, 3 are put into engagement through the couplings 9, 10, 13 by displacement of the slide 31 in one direction, and the shafts are disengaged by displacement of the slide 31 in the opposite direction by means including a control disc 22 mounted on the shaft 1. At the end of each metering period (comprising a plurality of measuring periods) a pushbutton 42 is actuated to tilt a latch 40 and allow a spring 38 to displace the slide 31. The slide 31 uncouples the drive from the meter disc 33, lifts a latch 27 to free the control disc 22 whilst allowing an arm 25 and wheel 20 to couple the disc 22 to the shaft 1 and pushes the shaft 1 axially to intercouple the shafts 1, 2, 3 through the friction couples 13, 9, 10. As it turns the shaft 3 restores the maximum demand indicator 8 to zero while the shaft 2 drives the counter 19 to register the value shown by the indicator 8. When the indicator 8 shows zero a stop 17 or a stop 46 prevents further rotation of the shaft 3 and the weakest of the friction couples 13 slips so that the shaft 2 also stops. The disc 22 completes a revolution, a cam 44 thereon displacing a rod 45 to push the slide 31 back against the spring 38 to be relatched by the lever 40. As the disc 22 continues the rod 45 slips off the cam 44 and the shafts 1, 2 are returned axially by the springs 11, 12 and when the revolution of the disc 22 is complete the latch 27 engages the detent 29 therein and presses on the arm 24 to lift the arm 25 clear of the wheel 20. The push-button 42 may be supplemented or replaced by a remote control switch operating a relay circuit through a make- and-break contact switch. The relay then releases the latch lever 40 and resetting proceeds as before. A spur gear fixed to the control disc 22 meshes with another having twice its diameter and rigidly connected to two cam discs of the make-and-break contact switch which is thus prepared for its next actuation by the remote control switch. Where a synchronous motor 5 is used for resetting the demand pointer 7 at the end of each measuring period it can also be used for resetting the maximum demand pointer 8 at the end of each metering period as already described. But where a relay 56 is used to time the measuring periods a servomotor 57 is used to drive the shaft 1, now made rigid with the control disc 22, only during resetting, for which the motor 57 is started either by closing contacts 61 through latch 27 after pressing button 42 or by closing the remote control switch, whereafter a cam 62 on the control disc 22 unlatches the lever 40 from the slide 31. When a revolution of the disc 22 is completed and the latch 27 re-engages the detent 29, the latch 27 opens contacts 61 and the motor 57 stops.