The daily Gate City. [volume] (Keokuk, Iowa) 1855-1916, 1915-04-22

IHlJhOlJAI AIN. ~, 1915
use standard or "ready-made" SUBJ
stations, rather than special designs.
The prime object in distributing high
tension power is to make profit for
the central station. Time is money,
and It costs both to call In operating
engineers to design stations, incur
drafting room expense, consume the
time of department heads, etc. When
1t is decided to supply consumer
from the high tension lines, try to
nse standard station, as there is a
type for practically every service.
The Standardization OF steel tower
outdoor sub-stations by the manufac-
turer is OF real Importance to the
user, as it eliminates the chance OF
error-always present when such
eauipment is designed by local men.
10 whom 1t is special or unusual
work.
II is interesting to note the rapid
decrease in cost per kilowatt with in.
creasing station capacity. This indi.
Gates that the original Installation
should be such that as the lead in.
creases, It's capacity can be increased
at minimum expense. With the stand
ard control and protective equipment
now available, it is simply necessary
TO replace the original fuses with
those Of heavier rating.
Air Break Switches.
Two types of switches, capable of
opening loaded circuits are available,
the vertically opening switch of the
single break form, and the horizontal
" opening switch Of the single or
double break form. The selection
will depend upon local conditions,
preference and possible Investment
Contrary to opinions held few
wears ago. tests now indicate that
no dangerous high frequency disturb
ances are set up by opening air
break switches. Spark gap tests tend
to show that voltage circuits set up
by the air break switch are less vio-
lent than those caused by oil break
switches.
One Of the requirements OF pole
top switches Is that they be capable
of operating under heavy ice condi-
tons, such az following severe sleet
storms To determine the effect of
ice formations, many tests have been
conducted. the switches being heavily
coated.
High Tension Fuses.
Short circuits on high voltage sys-
tens have always ranked among the
most potent Of trouble makers. If
the line is not cleared quickly and
completely, serious trouble and de-
struction may follow. Otter the volt
age OF the entire system will be
pulled down, or under severe short
circuit conditions, the generators,
transformers or other apparatus seri-
ously damaged. Again, If short cir
cults on high tension feeder lines
are not cleared quickly, the station
automatic switches will be operated
and the entire main line shut down.
For use in connection with rela-
lively small ampere capacity loads,
the automatic high voltage oil circuit
breaker is handicapped. due to its
high initial and installation costs
The practical method Of interruptins
these high voltage circuits is by
means of fuses which will clear the
circuits Just as, or even more, quickly
than the expensive oil circuit break
ers.
One of the most successful types
developed Is the chemical form, con-
sisting Of short fuse wire under ten
sion and Theoretically sealed in
glass tube filled with carbon-tetra.
chloride solution. This form Of fuse
has the desired characteristics Of
quick action, minimum disturbance
to the system, positive Indication
whether open or closed. and ready re-
placement.
Aside from exhaustive engineering
tests, this fuse has been in success
full commercial operation sufficient,
length OF time to thoroughly demon
strate its characteristics. Many short
circuits have occurred on high ca
pacity systems-and in every in.
stance, the fuse has cleared the
lines without danger to either the
feeders or generating installations.
Chemical Fuse Operation.
The operation of 66,O00-volt fuse
is we'll illustrated by oscillograms
taken during a series Of tests at one
of the largest hydro-electric power
stations in the world. A standard
fuse rated at 66,000-volts was con-
nected between one phase and nell
trail OF the 110.000-volt buses, sup
three 5000 K v. A. generating units
SSuuSCIeu III parallel ne oSSihc' |
gram records show the short circuit !
current and voltage across the fuse
at the time OF short circuit, the po-
tentials indicated by waves No. / |
and No. 2, being taken on the pri-
mary and low voltage side Of the
transformers stepping from 1000 to
110.000-volts.
1t Is interesting to note that those
fuses rated at $4,000 volts were con-
nected between one phase and neu-
trail of the ITO, 000-volt buses and thus
subjected to approximately 66,oco
volts, where as on commercial 10000
volt circuits, two fuses would always
be in series at time OF short circuits /
between phases. In case OF short !
circuit between one phase and ground