. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . he upper left-hand corner of thediagram, but for simplicitys sake the wiring is not given in full. Atvarious points of the power-board wiring, however, are seen arrowheads,with such designations as , , etc., which indicate the points atwhich the various voltmeter switch connections are made. Beneaththe voltmeter are the ammeter circuits. One of the ammeter shuntsis used for measuring the current of each charging machine, and the thirdis used for measuring the current flow from the battery to t
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . he upper left-hand corner of thediagram, but for simplicitys sake the wiring is not given in full. Atvarious points of the power-board wiring, however, are seen arrowheads,with such designations as , , etc., which indicate the points atwhich the various voltmeter switch connections are made. Beneaththe voltmeter are the ammeter circuits. One of the ammeter shuntsis used for measuring the current of each charging machine, and the thirdis used for measuring the current flow from the battery to the automaticswitchboard. In Fig. 283 is shown the power switchboard wiring digram of a mainoffice with three sub-offices. In these offices the ringing current andbusy-signal current are furnished by harmonic converters. The chargingis done by means of rectifiers. As indicated in the lower right-handcorner of the diagram, each rectifier is connected to a 220-volt, 60-cycle,single-phase commercial power circuit, by means of an insulating trans- 350 AUTOMATIC TELEPHONY ? O// QODU 4UI. POWER PLANT, SUPERVISORY AND TESTING EQUIPMENT 351 former. The use of such a transformer is common practice, to avoiddanger from a punctured transformer on the commercial power reactance coil is connected between the rectifier and the charging mainsto eliminate any noise on talking circuits. As indicated, the batteries at each of the sub-offices may be chargedby means of the rectifiers at the main office through a rheostat placed inthe negative battery feeder of each sub-office. No positive batteryfeeder is provided, because the connection for the positive side is madethrough the earth, reinforced, quite often, by the sheath of the cablesupplying the trunks to each sub-office. Rectifier*Z Pect, i ReactCoil .16 6 Busbar► -50~ « » In Supy Cab.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
