. The Street railway journal . cessitated by the fact that the storage battery requires tobe charged at about 25 volts and discharges at full load at about20 volts. Therefore the rotary transformer must charge at therate of from 500 to 25 and discharge at the rate of 500 to 20. Thisperformance is obtained by adding to the windings of the machinea 500-volt field coil which is connected, not to the terminals of therotary converter, but to the trolley and ground. Hence, when thepower house current is absent, the motor dynamo receives theexcitation from the low potential side and gives the greater
. The Street railway journal . cessitated by the fact that the storage battery requires tobe charged at about 25 volts and discharges at full load at about20 volts. Therefore the rotary transformer must charge at therate of from 500 to 25 and discharge at the rate of 500 to 20. Thisperformance is obtained by adding to the windings of the machinea 500-volt field coil which is connected, not to the terminals of therotary converter, but to the trolley and ground. Hence, when thepower house current is absent, the motor dynamo receives theexcitation from the low potential side and gives the greater ratioof transformation. When the power house current is at hand, thehigh voltage coil produces the proper changes in magnetizationto alter the ratio of transformation as required. Another interesting exhibit at the Beach consisted of a largeswitch for handling heavy locomotive work. This switch is shownon the opposite page, photographed beside a switch for ordinarystreet railway work. The switch weighs nearly 400 lbs. and has. May, 1899.] STREET RAILWAY TOURNAL. 327 very powerful and massive jaws, which carry the necessary cur-rents for handling 80-ton and 90-ton locomotives. These jaws arereinforced by carbon contacts which will take any arcing whichmay occur there. These arcs, however, as a matter of fact, areslight because of the series coil device. The cost of this system has given rise to a great deal of specula-tion, and as the Safety Third-Rail Electric Company has not yetgotten its equipments on a manufacturing basis, definite figurescannot be given, but it is believed that the cost of this system willnot exceed that of an equivalent first-class overhead system. The only serious item of depreciation in the system is theswitches, and as these consist of about one-third of the total in-vestment for outside electric construction, they can suffer a verylarge depreciation without bringing the total depreciation figuresto any serious magnitude. In fact, the company proposes
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
