. Electrical world. f 800 kw atI the generator end, while Fig. 8 shows thecombined efficiency for an output of 1,066I kw, 100 per cent, power factor on both ma-I chines. The combined efficiency includesI all the losses of the motor and generatorand the bearing friction and windage of theset At an output of 800 kw at 100 percent, power factor the combined efficiencyof the set is per cent., and at an outputof i,o6s kw at 100 per cent, power factorthe combined eflaciency of each set reachesthe extraordinarily favorable value of 91per cent ^^^- ^-—io6s-kvv., 2,300-voLT, three-phase, 6o-cycle
. Electrical world. f 800 kw atI the generator end, while Fig. 8 shows thecombined efficiency for an output of 1,066I kw, 100 per cent, power factor on both ma-I chines. The combined efficiency includesI all the losses of the motor and generatorand the bearing friction and windage of theset At an output of 800 kw at 100 percent, power factor the combined efficiencyof the set is per cent., and at an outputof i,o6s kw at 100 per cent, power factorthe combined eflaciency of each set reachesthe extraordinarily favorable value of 91per cent ^^^- ^-—io6s-kvv., 2,300-voLT, three-phase, 6o-cycle generator. The frequency changers are started from the exciters. The ex- other effect than to increase the cross currents, it is at once evidenttiters are good for 73 kw at 120 volts. Although the excitation of that the field currents have to be adjusted properly before the machineseach machine does not exceed 18 kw under any conditions of load, are thrown in parallel. Hence, assume the first set in operation with. 310 ELECTRICAL WORLD and ENGINEER. Vol. XLIII, No. 7. 125 amp. excitation on the fields of the generator. If we wish tothrow the second set in parallel with the first set, we first syn-?chronize the motor of the second set and then make the excitation ofthe generator of the second set 125 amp. The bus-bar voltage on•which the first set is operating is 2,300 volts; the second set hastlie same excitation and the terminal voltage of its generator is, there-fore, greater than the bus-bar voltage on which the machine is tooperate. Assume the drop of the machine at this load to be 12 percent., then the generator of the second set at 125 amp. excitationon its fields will generate 2,580 volts. The switches must be closedbetween the two machines at these unequal voltages and the two setswill pull each other in parallel with the load distributed equallybetween aggregate power of the frequency changers in this sub- Radioactivity and Radiation. •100 -90 -80TO >
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
