Patent GB-227104-A (GB)
Title: Improvements relating to electrical measuring instruments for alternating-current circuits
IPC: G01R13/04
Filed: 1924-12-24
Abstract: 227,104. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Smith, B. H.). Jan. 2, 1924, [Convention date]. Recording by distinctive marks.-An alternating-current supply meter registers the consumption in watts and effects a record on a chart representing the volt-ampere demand and also the watt demand averaged over a predetermined time interval. An energy meter, 3, Fig. 1, and a reactive voltampere meter 2 combine to operate a device 5 by means of which a recording stylus 12 is given a motion proportional to the volt-amperes. The recording mechanism is periodically zeroized by clockwork 7, the chart 31 being at the same time advanced by a short distance so that a new curve is drawn by the stylus 12 during each separate time interval; the total length of this curve represents the volt-ampere demand, while during its return to zero the stylus 12 makes a mark 210 representing the watt demand during the same time interval. The meters 2, 3 drive shafts 45, 46 carrying at their ends discs which drive frictionally a ball 50 in the device 5, shown in Fig. 4. This ball is supported by the meter-driven discs, of which the one 48 driven by the shaft 46 is shown, the points of contact being 90‹ apart relatively to the centre of the ball 50. The ball also rests on the periphery of a disc wheel 51, forming a third point of support, and is prevented from displacement by a guard 52. The disc wheel 51 is frictionally driven by the ball 50 at a speed proportional to the volt-amperes, the motion being transmitted through a gear train 121, 131, 130, 135, 140, 141 to a shaft 142. The disc wheel 51 and the gearwheels 121, 131, 130 are carried by a frame 122 pivoted on trunnions 124, 125 so as to be rotatable about an axis passing through the centre of the ball 50. The axis about which the ball 50 rotates is dependent on the ratio between the speeds of the meter-driven discs by which it is driven, i.e. on the power-factor. The disc 51, and consequently the frame 122, takes up a position corresponding to this axis, the power factor being indicated by a pointer 113 carried by the frame 122 and moving over a scale 115. The shaft 142 drives, through a spur-wheel 145, Fig. 3, and crown-wheel 146, a vertical shaft 147 on the meter 2. This drives, through a worm 149, worm-wheel 172, shaft 173, and reduction gearing 174, 176, a sleeve 160 fixed on a shaft 161 and having trunnions 165 on which is pivoted a depending arm 167. Mounted in the energy meter 3 is a shaft 77, Fig. 5, having fixed thereto a sleeve 82 provided with lateral projections 87. These carry trunnions to which is pivoted a yoke 86 having a depending portion 91 to which the stylus 12 is secured. Loosely mounted on the shaft 77 is a sleeve 90 driven from the shaft 18 of the energy meter through a pinion 65, gear-wheel 66, vertical shaft 67, worm 96, worm-wheel 97. horizontal shaft 98, and gear-wheels 99, 100. The sleeve 90 carries a pin 92 and a zero-setting worm and gear train 94. The depending portions 167, 91 are connected by a link 168, Fig. 7, so that the stylus 12 is moved at a rate proportional to the volt-amperes. The shaft 98 also carries a worm 104 engaging a segmental gear member 105 mounted on a shaft 102 and adapted to engage a pin 106 on the worm-wheel 97. The sha.ft 98 is journaled at one end, and the shaft 102 is mounted, in a bracket 108 pivoted on a pin 109 and normally held against an abutment by a spring so that the worm-wheel 67 is in engagement with the worm 96. In the meter 2 is a similar segmental gear member 179, Fig. 3, adapted to engage a pin 181 on the worm-wheel 172. The shaft 173 of this wheel is journaled at one end in a bracket 183, pivoted at 184, and carrying the shaft 180 of the segmental gear member 179. The bracket 183 is normally spring-held against an abutment so that the worm-wheel 172 is in engagement with the worm 149. At the beginning of a time interval the stylus 12 is in its initial position and the segmental gears 105, 179 are in the paths of the pins 106, 181. The wheel 172, Fig. 3, starts to rotate so that the pin 181 moves away from the segment 179, which at the same time is moved bv the worm 178 away from the wheel 172. The stylus 12 therefore is moved over the chart at a rate proportional to the volt-amperes. At the same time the wheel 97 rotates so that the pin 106 moves away from the segment 105, which is also moved away from the wheel 97 by the worm 104. The pin 92 is thereby moved at a rate proportional to the watts, which is never greater than the volt-amperes. At the end of a time-interval a rod 34, Fig. 1, is moved to the left by the clockwork 7 thereby moving the brackets 183, 108 away from their abutments and disengaging the worm-wheels 172, 97 from the worms 149, 96, the bracket 183 being moved in advance of the bracket 108. The stylus 12 is thereupon moved to its initial position by the action of gravity on a counterpoise. Since the corresponding disengagement of the gear-wheel 97 has not yet occurred, the projection 87 engages the pin 92, causing the stylus to make a mark 210 representing the watt-hour demand for the time period. Disengagement of the wheel 97 from the worm 96 is then effected, leaving the pin 92 free to return to its initial position under the action of a counterpoise.