25 
tion motors which drive the mill tandem. The complete installation 
was made by an American company that has had considerable ex- 
perience in electrifying sugar mills in Cuba. 
The feasibility of complete electrical operation in a sugar mill 
having been proved, other mills became interested. At the end of 
1929 three more mills had completed their electrical installations. 
These mills were all equipped by a German company, which obtained 
the bids by offering lower prices and longer terms than its American 
sompetitor. Details of the three mills which were electrified during 
1928-29 are as follows: 
Quear mill 
Bedadreng....cocoeann 
SoIMBOrO. anes sans annans 
OenSENERAT maemo 
Capacity of generators 
Current 
1,350 kilovolt amperes_............. Alternating... 
saci Ousva peammmmanpenmrme pms ogin wid 
1,000 kilowatts oo oooocaeooanaan. directo... 
,600 kilovolt amperes... _......... \lternating... 
L000 kilowatts. ooceooeeooaeooooo. Directo... 
#00 kilovolt amperes....-....._..| Alternating. ..| 
»Y 1,600 kilovolt amperes... __..do....._._. 
3v 1,000 kilowatts. .o.oomeoooooo) Directo... 
Ty 19 kilowatts ooo eceonyeee On 
4by7 Bos emoeeaion aR en 
»y 100 kilovolt amperes..........} Alternating... 
yy 4 kilowatts. _ mcemmeeee Directo... 
Voltage | Prime mover 
100/23 
100/231 
160/225 
180/220 
160/225 
120/990 
Steam turbine, 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Motor. 
Do. 
Diesel motor. 
Motor. 
160/320 
230 
230 
270/380 
290 
it is probable that other additional Java sugar mills will install 
slectrical equipment, particularly if experience proves that lower 
operating costs result from such installations. With world sugar 
prices at their present levels the argument of economy of operation 
will have a strong appeal. This same price situation, however, may 
result in ducking the tendency to invest in expensive new equipment 
until conditions improve. 
MINING INDUSTRY 
Coal mining. —FElectrical energy is used extensively in the Govern- 
ment owned and operated coal mines in Sumatra, the total installed 
capacity of the mines being 9,350 kilowatts. - At the Ombilin coal 
mines on the west coast, three steam turbines, one A. E. G. of 2,750 
horsepower capacity and two Stork machines of 2,500 horsepower each 
are installed. The A. E. G. turbine is connected to a generator of the 
same make, while Smit generators of 2,000-kilowatt capacity each 
are connected to the Stork turbines. The current is used chiefly to 
operate the direct-current locomotives which carry the coal in the 
mines and for operating ventilators and electrically driven air com- 
pressors, as well as for general lighting purposes. 
Prior to 1921 the motive power for the Poeloe Laoet mines was 
generated by steam, but this was not entirely satisfactory and two 
turbogenerators of 1,000-kilowatt capacity each have been installed. 
In 1927 a further addition was made when another unit of 1,000- 
kilowatt capacity was added. The three steam turbines are Stork 
machines and are coupled to Smit generators. The electric installa- 
tion at Poeloe Laoet made it possible to operate with electric motors 
their pumps of 2 to 4 cubic meters per minute capacity, the lifts, and 
the ventilators. An air-compressor plant for the operation of the 
pneumatic-drilling machinery, with an air capacity of 3,000 cubic 
meters per hour, is also operated by the power generated in the 
electric plant.