Peninsula enterprise. [volume] (Accomac, Va.) 1881-1965, 1904-04-09
ELECTRIC CAR FUSES.
what IL Is That Happens When They
cBIow Out"

~
CBIOw Out"
One often sees a bright flash ana
sudden stop of an electric car, with all /
the lights out. This is frequently de-
scribed as a more or less serious acci-
dent, and it often causes panic among
the passengers, especially on elevated
trains. The greatest danger to pas
sengers, however, is o,sibie panic
which might be avoided II II was gen
erally known how little chance there
is of fire or other danger. Inc Eiec-
trical Review, to help people to under
stand what happens, makes the follow
ing explanation, which should be pam
10 Law minds: IF steam engine Is
overloaded ii will stop and refuse 10
work. although the full pressure OF
steam may remain upon the piston ana
not cause any damage. On the other
hand. a motor when overloaded lrleS
its best to do the work thrown upon It,
Ifit cannot run at full speed it Will run
at whatever speed it can. AS the speed
decreases the current through the mo-
for increases. and the motor adjusts IT.
self TO that speed at which the turning
effort is sufficient to cause rotation anu
do the work. If the effort demanded
OF the motor is so great that the cur
rent which passes through 1t wheh
standing still is not sufficient to cause
rotation the motor will, of course not
turn Int the current will continue 10
flow unless interrupted by n suitable
mechanism.
"The current which will flow through
motor when il is standing sun Is III
almost all cases far in excess OF lha'
which the motor is designed to carry
and. indeed, in a we'll designed motor
a current dangerous for the motor Will
no reached before the motor has been
stalled. The effect Of this heavy cur
rent OH the motor, if allowed TO con-
tipue. is to heat the windings to dan
gerous degree and destroy the lnsula-
ton. possibly setting it ON fire. anu IL
is to prevent this occurrence, whether
due TO careless handling of the car or
TO unexpected causes, that the fuses
are used. A fuse is simply a short
niece of wire Of such size that II VIII
be melted by a current which, II alio"
ed to flow through the motor 1or any
time will damage It, When tust
blows, then, it simply means that one
Of the safety devices on the car has
operated TO prevent damage to the mo
tor. The melting of the fuse opens the
circuit and cuts off the current iron
the motor. To protect the car the russ
is inclosed in tireproof box.
There is another device for accom-
plishing this purpose, which Is KNOW
as the circuit breaker. This is SWITCH
controlled by an electro magnet, whlcl
onens whenever the current reaches
certain dangerous value. This mechan
ism is now generally installed upol
electric cars in addition to the fuse.
is often placed on the roof of the pla'
form over the motOrman's head, Wher
II is easily reached, and it is set I
operate at higher current value ina
the fuse, because the circuit breaKe
acts almost inStantaneOusly, Wnlle
takes a little time for the fuse to b
melted. Now, a motor car can stan
for a second or two a current Whlc
would destroy it if applied for longe
period. The circuit breaker, then, take
care Of heavy overloads, and the rus
protects the motor against those SINAI
or currents which are dangerous II al
piled for a considerable time.
when fuse blows out, there Is ger
orally a volatihzation of the metal
the fuse and a slight explosion. Thes
explosions usually cause report an
some smoke. When the circuit breake
is opened, it draws an electric are
breaking the circuit, and, as In this al
q considerable amount Of energy Is oil
sipated in heating the air, there may
here also something of an explosion
but In neither case is there any dang
to the passengers when the apparat'
is properly installed. The fuse and II
circuit breaker are safety devices, II
operation Of which indicates not ID
there is danger to those on the car, d
that danger to the motors has be-
9verted."