Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1942-06-27
SAYS
He0r Ye. Hear Ye

! Most electrical equipment IS very
silent operating, particularly when
compared to q ball mill or crusher. In
fact, some motors are so quiet that one
must listen attentively to make sure
that they are running. Montana KiIo-
watt saw one shop installation of a
$500 rpm. bench grinder with a red
pilot light above it, because it ran
so quietly that It was often left on
all night. Motor starters, transformers.
and most other equipment are likewise
silent operating.
Since most Of the time YOU prob
ably don't hear your electrical equip
ment above the din from surrounding
machinery, it is well to heed any noise
you may hear. The noise may be a
symptom of a defect which would
cause failure If not corrected.
For example, a growl in a motor
may indicate worn bearings permitting
the rotor to run closer to the stator
IRON on one side. Continued operation
IN this condition can cause complete
failure Of the motor.
During one of Montana KiIowatt's
visits to a mine, he heard an extreme
~ noisy vertical deep well pump mo-
tor. The noise was a cross between a
ball mill and fire siren. The cleo
trician informed him that this motor
had been noisy for some time. The
motor was stopped, the pump shaft
released, and the bearing opened for
inspection. It was a sorry looking mess
because the ball bearing retainer had
broken and was ground into hundreds
Of pieces. The bearing races and balls |
were very rough, and except for the |
timely inspection, complete failure |
would very likely have occurred.
A growl in motor also may indi- |
cate partial short circuit of a coil |
which is almost sure to fail in a |
short time unless corrected.
A minor repair job viii often cor
'ect the trouble.
Complete failure may leave you out
N a limb as an A-1-J or better pri-
'rity rating is required to obtain cop
Ter coils according to the latest in
ormation available to Montana Kilo-
watt. Even with this high priority II
ating it would probably take two
months or more to obtain the coils.
A growl In transformer is very
'ften indicative of a short circuit be-
ween coil turns which viii cause fall
ire if not corrected.
A groWl in a magnetic starter gen.
rally indicates poor joint between
he iron core on which the coil is
counted, and the movable iron arma-
ure which operates the contact mech
nism. This often leads to overhead
ag and turnout of the holding-in coil
Mess corrected. With a fine file and
ONE "Prussian blue" the high spots {
n the iron faces that come together
an be filed off to restore good contact
( the entire face.
The splitting noise of an electric arc ]
always an indication of trouble, lex
spt, Of course, around an arc welder {
r arc furnace). Trace the noise to +
,cate the arc and Immediately corr Z
sct the trouble. Flashovers and arcs
re caused by a breakdown of the in A
llation surrounding or supporting q \
1nductor. The insulation breakdown
ay be caused by using materials suit
BILE for dry locations in moist loca- :
ons. For example, ordinary wood is Z
very fine insulator in dry locations, :
Ut in damp mine shaft it isn't r
orth dam. II
So instead of Stop, Look and Listen;
DIV about Listen-Stop-Lo ii