GB953358A - Prepayment watt-hour meter - Google Patents

Abstract

953,358. Prepayment electric meters. J.C. DAVIS. Nov. 19, 1960, No. 39544/60. Heading G4V. A prepayment watt-hour meter comprises means 104 responsive to the depositing of coins in a collector 14 for causing an indicator 62 to indicate the watt-hour credit of a customer, a circuit for connecting the meter 10 to a load 46 and to a source T2, T3 of electrical energy, switching means 164,166 for closing the circuit when the indicator registers a credit, and means including a contact device 34 responsive to the drawing of energy from the source for reducing the indicator reading. The indicator 62 is mounted in a shaft 64 carrying a cam 68 and a toothed disc 66, the teeth of which are engaged by armatures 74, 106 movable against springs 80, 110 by the energization of coils 72,104. The coil 104 is energized to move the indicator step-by-step each time a coin is deposited in a shoot 130 and falls on a switch 112 until such time as the maximum permissible credit has been purchased and the cam 68 opens a switch 118 to deenergize a coil 136 to permit a flange 140 on an armature 138 to extend into the shoot to prevent the further insertion of coins. The coil 72 is energized to move the indicator in steps corresponding to the amount of electrical energy consumed by the closing of the contacts 34 by projections 371 on a disc 37 rotated by gears 38, 30 driven from a worm 28 on a shaft 26 carrying the disc 20 of the meter which has voltage and current coils 22, 24. When the contacts 34 close, solenoids 45,47 are energized in such a way that first an armature 42 is moved so that an extension 44 presses the contacts firmly together and then an armature 39 is moved about a pivot 40 against a spring 41 to move the projections out of engagement with the contacts which then reopen. When the indicator approaches the position indicating that no credit remains, the cam 68 open contacts 100 to de-energize a relay 160 and open the contacts 164, 166 to disconnect the connection 46 to the load from the terminals T2, T3 of the source. In other embodiments, the disc 66 and armatures 74,106 are replaced by two pawls and a ratchet together with a differential gear assembly.