. Electric railway journal . the auto-matic float switches governed by the water level inthe storage reservoir. The first circuit completed bythe drum controller is through a relay which startsup one or the other of the exciter sets, depending onwhich way a triple-pole, double-throw switch is 150-hp. motor of this exciter set is thrown di-rectly across a 2300-volt line taking momentarily eighttimes full-load current and coming up to full speed andfull voltage in three and a half seconds. Meantimethe drum has continued to revolve and has closed thenecessary circuit to energize the ga
. Electric railway journal . the auto-matic float switches governed by the water level inthe storage reservoir. The first circuit completed bythe drum controller is through a relay which startsup one or the other of the exciter sets, depending onwhich way a triple-pole, double-throw switch is 150-hp. motor of this exciter set is thrown di-rectly across a 2300-volt line taking momentarily eighttimes full-load current and coming up to full speed andfull voltage in three and a half seconds. Meantimethe drum has continued to revolve and has closed thenecessary circuit to energize the gate motor whichopens the gate on the water wheel to about fullopening. After completing this contact the drum con-troller stops until the generator reaches a speed of , at which time a centrifugally operated switchon the top of the generator shaft makes a contactwhich starts the drum revolving again. This thencompletes the circuit which closes the main line con-tactor, putting the machine on the line without field. and in series with a set of reactors which will limitthe current through the unit to about times full-load current during the synchronizing period. Two ofthese reactors, which are of the single-phase oil-im-mersed type, designed for five-minute duty, are in-stalled for each machine. A time interval between theclosing of the centrifugally operated switch on the maingenerator and the closing of the main line contactor isprovided in order to permit the generator speed toincrease from 55 to 60 , or synchronousspeed, before the main-line contactor is closed. Thenext function performed by the drum is to close acircuit through the field coils. When the exciting cur-rent is first thrown on the generator field, it is limitedby the field rheostat connected in the circuit to aboutone-quarter normal value. This gives the machine achance to get in step, without unduly high currentvalues. After a moment a section of the field rheostatis shunted out, inc
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyorkmcgrawhillp
