. The Street railway journal . the three-phase system of electrical power transmission as developed bythe General Electric Company, which has proved so satisfactoryin the majority of power transmission installations of varyingsizes and varying distances in this country. One peculiar feature of the Portland installation is the em-ployment of large blocks of power for street railway service,involving the transformation of the polyphase current sent overthe line into direct current for railway circuits. The frequencyis thirty-three cycles per second, selected on account of the largeamount of powe
. The Street railway journal . the three-phase system of electrical power transmission as developed bythe General Electric Company, which has proved so satisfactoryin the majority of power transmission installations of varyingsizes and varying distances in this country. One peculiar feature of the Portland installation is the em-ployment of large blocks of power for street railway service,involving the transformation of the polyphase current sent overthe line into direct current for railway circuits. The frequencyis thirty-three cycles per second, selected on account of the largeamount of power which it was necessary to convert from alter-nating into direct current. The current is delivered directly tothe line without first passing through transformers and when itreaches Portland is transformed down to a potential of 400 the power service the step-down transformers are connectedto rotary converters which will deliver a continuous current of500 volts for street railway service, as well as for the operation. FIG. 1-INTERIOR OF STATION, SHOWING THREE-PHASE GENERATORS AND D. C. EXCITE.^S, PORTLAND. forty-two inches and sixty inches in dianieter respectively. Thelarger wheel is an auxiliary to be brought into service only atperiods of excessive high water, which the records show occurabout once in every five years. The smaller wheel runs at aspeed of 200 revolutions per minute and the larger at 100 revo-lutions per minute. Both turbines are set at the same leveland each carries a pulley; that of the 60 inch wheel being fixedto the generator shaft. When the large wheel is in operationthe two pulleys are belted together, the smaller wheel is dis-connected and the large wheel drives the generator at a uniformspeed of 200 revolutions. When the smaller turbine is operatedalone the belt lies upon a shelf surrounding the pulleys. The length of the generator shaft is twenty-nine feet. Itis not a continuation of the shaft of the wheel but is coupledto it by means of a d
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
