. Journal of electricity, power, and gas . ly is this true with small commercial estab-lishments, such as the poorer classes of restaurants,saloons, tailor shops, etc. The prepayment meterwhen installed in such places will oftentimes obviatedifficulties which may otherwise arise. The prepayment device can be furnished either asan integral part of the watthour meter, or as a sep-arate device. The construction and operation in eithercase is essentially the same, except that in the formercase the connection to the meter is mechanical and inthe latter case it is electrical. Fig. 73 illustrates the
. Journal of electricity, power, and gas . ly is this true with small commercial estab-lishments, such as the poorer classes of restaurants,saloons, tailor shops, etc. The prepayment meterwhen installed in such places will oftentimes obviatedifficulties which may otherwise arise. The prepayment device can be furnished either asan integral part of the watthour meter, or as a sep-arate device. The construction and operation in eithercase is essentially the same, except that in the formercase the connection to the meter is mechanical and inthe latter case it is electrical. Fig. 73 illustrates theprepayment device attached directly to the watthourmeter, in which case a pinion in the registering mech-anism of the meter meshes directly with the debitingmechanism of the device. In case the prepaymentdevice is used separately from the watthour meter,the debiting mechanism is controlled by an electro-magnet which is connected directly in the line, con-tact being made through suitable gears and commu-tating device in the meter Fig. 74. of coins to the credit of the consumer and does nottake into account the coins for which energy has al-ready been delivered. The total number of coinsplaced in the device can always be readily translatedfrom the watthour register by multiplying the readingin kilowatt hours by the rate per kilowatt and divid-ing the result by the denomination of the coin. Whenall the energ}^ which has been paid for has been de-livered, the crediting hand moves back to the zeroposition and opens an internal switch, which cannotbe again closed until another coin is deposited. Theswitch contacts are made of laminated copper stripswhich insure good electrical contact. The force which actuates the debiting device con-sists of a large spiral spring. This spring exerts prac-ticall) a constant force, since it is so designed that itis always operating under a low percentage of itsmaximum tension. The gearing mechanism of thespring is differential in operation,
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Keywords: ., bookcentury1800, bookdecade1890, bookidjo, booksubjectelectricity
