ALTERNATING MOTORS FOR RAILWAY WORK. 197
The station generating apparatus has the same cost as be-
fore. The reducing transformers may be taken at $4000.
The whole feeder system would be at high tension, and
there would be no need for raising transformers, since the
fairly large station generators could well give 5000 volts
and be overcompounded for, say, ten per cent loss in the
line. The cost of machines for such voltage might be
slightly higher, perhaps $rooo on the plant. A like
amount should be added for high tension switchboard and
extra appliances. Now the total energy in this case is
transmitted an average distance of 34,000 ft., as in the
booster distribution. Using the same formula as in the
preceding case we have, allowing ten per cent line loss,
and fifteen per cent extra current to compensate for lag,
L 4463 X 138 X 1150
500
of copper, costing $6312. It is but fair at present to as-
sume an extra cost of fifty per cent for the car equipments,
say, $500 per car for fifteen cars, in all $7500.
We may now gather these data as follows :
W = 42,078 1bs.
Cost of Cost of Cost of 1o on 10%on Extra Sum of
Case. copper. Extra 2,000,000 copper., extra labor for these
apparatus. kwh, app. working., anuual
charges.
L $24,276 $35.000 $2,427 $37,427
EE 72,628 ' $ 2,500 30,000 7,262 $ 250 37,512
EEL 32,288 14,600 30,000 3,228 Y400 $2,560 - 37128
IV. 6,312 13,500 30,000 635¢ 1,750 31,981
These figures speak for themselves. In reality IIT is,
under the assigned conditions, decidedly inferior to the
others in efficiency, as already indicated. It can only be
used economically under rather rare conditions, and then
only in default of a proper alternating motor system. I
and II are almost exactly epuivalent, and very small differ-
ences in cost of power generation would throw the advan-
tage one way or the other. IV is easily the best, and
would still hold its position of superiority in the face of a
considerably larger allowance for lagging current than that
here made. With a smaller permissible loss of energy than
fifteen per cent, the booster system would drop rapidly to
%