Patent GB-185738-A (GB)
Title: Improvements in and relating to polyphase electric meters
IPC: G01R11/56
Filed: 1922-09-05
Abstract: 185,738. New Antwerp Telephone & Electrical Works, Soc. Anon. Sept. 8, 1921, [Convention date]. Indicating maximum movements.-In an arrangement of electric meters for polyphase circuits the maximum current obtained by integration over given intervals of time is indicated on a maximum-demand indicator, and separate indicators indicate quantities such as the average power during the time of maximum current and the distribution of this average power and of the total energy consumed in the different phases. The shafts 3, 3<1> of two induction meters 1. 1<1> operate registering mechanisms 5. 5<1> continuously to register the components of the total energy consumed, and drive pinions 8. 8<1> normally engaging integrating gear-wheels 9, 9<1> against the action of springs 15, 15<1> at rates proportional to the components of power. A current meter 34 turns a pinion 50 at a rate proportional to the sum of the squares or of the first powers of two of the main line currents. The pinion 50 normally engages a gear-wheel 51 and rotates an arm 58 against the action of a spring 59, but is released from the wheel 51 by the armature 53 of a solenoid 54 periodically switched into circuit by a rotating switch 66 driven by clockwork. The arm 58 is thus periodically rotated through an angle proportional to the average current in each period, and, if this average is a maximum, the arm 58 contacts with and operates an arm 62 carrying an indicator 63, which thus indicates the maximum average current during periods determined by the speed of rotation of the switch 66. The contact of the arms 58, 62 closes circuits controlled by the switch 66 and including electromagnets 31, 31<1>, which, when energized, attract armatures on pivoted gripping arms 20, 29<1> against the action of springs and so release discs 25, 25<1> carrying indicators 26, 26<1>. The discs 25, 25<1> are connected through arms 23, 23<1> to springs 21, 21<1> of less strength than the springs 15, 15<1> and connected at their other ends to the shafts 14, 14<1> of the wheels 9, 9<1> The indicators 26, 26<1> thus give the average power consumed during the period of maximum current and are operated only at the ends of such periods of maximum current when the indicator 63 is operated. At the end of each period of time, the switch 66 closes the circuits of electromagnets 54, 12, 12<1> the armatures of which release the pinions 50, 8, 8<1> from the wheels 51, 9, 9<1> and so allow the latter to return to their starting points under the action of springs 59, 15, 15<1> and of tappets 19, 19<1> actuated by the electromagnets 12, 12<1> against the action of springs to engage cams 17. 17<1> on the shafts 14, 14<1>. The springs 15, 15<1> may be dispensed with. The switch 66 may comprise two rotating cams 67, 68 engaging two pairs of spring blades 69, 70 co-operating with fixed contacts 73, 75, one of the blades of each pair being shorter than the other and the cams 67, 68 being insulated from each other or of insulating material. The arrangement is such that a circuit to the arm 62 and through the arm 58 if it is contact with the arm 62 is periodically established for a sufficient time to allow the indicators 26, 26<1> to set, and that immediately afterwards a circuit is established through the solenoids 54, 12, 12<1> for a sufficient time to allow the wheels 51, 9, 9<1> to return to their starting points. The average distribution of energy in the phases in non-inductive circuits and the average power-factor in inductive circuits are obtained from the readings of the mechanisms 5, 5<1>, whilst the distribution in non-inductive circuits corresponding to the period of maximum average current and the power factor in inductive circuits corresponding to such period are obtained from the readings of the indicators 26, 26', calculation or a graphical calculator being necessary in the power-factor observations. The indicators 26, 26<1>, 63 may be returned to zero periodically by hand.