turns, the fuse will be blown repeatedly, and the blowout occurs particularly
at the instant when you close the knife switch.
Remedy
Check the terminals and the outer casing to see whether they are
short-circuited,
and
measure
the
resistance
of
each
phase
with an
avometer.
If
short
circuit
occurs
or
the
resistance
of
a
certain
phase
is low,
this means
that
short
circuit
does
exist
in
the
windings
and/or
between
turns, and
insulation
layers
have
been
burned
or
deteriorated. A
megameter
can
be
used
in
this
inspection,
too.
I
f
the
insulation
resistance
is lower
than
2 M - Oh m,
this
means
that
the
insulation
layer
is
already
breakdown.
If
the
motor
has
been
burned,
repair
it
or
replaced
it
with a new
one.
b) Fault of control relay
Analysis of Trouble
Overheat,
burnout
or
wear
of
control
relay
contacts
may
occur
generally.
All these will cause poor contact in electricity.
Remedy
Dismantle
it to repair, or replace it with a new one.
c) Poor electric contactor in thermostat
Analysis of Trouble
Burnout
of
contactor
and
leakage
of
temperature
sensing
agent may
occur generally.
Remedy
Replace the old
with a new
one.
d) Check
the
terminals
for
loose
connection
and
electric
circuits for
other abnormal
phenomena.
5) Mechanical faults
of compressor
a) Seizing of shaft
This phenomenon
is
caused
mostly
by
poor
lubrication,
such ad
insufficient
quantity
of
lubricant,
clogging
in
the
lubricant
oil
line, or
intermittent
lubricant
oil
supply.
Dirt
and
other
impurities
in
the
lubricant oil
will increase
its
viscosity
and
cause
the
shaft
to
be
seized.
Copper
plating
may also result
in seizing of shaft.
b) Seizing
of piston
This is
caused
by
too
small
fit
clearance
between
the
piston and
cylinder or expansion due to heat.
Judgement
of
seizing
shaft
and
piston:
After
the
refrigerator
has been
powered
on,
the
compressor
will
not
start
and
run,
but
a
slight
hum
sound
can be heard, and several seconds later, thermal protective relay will
actuate and make the contacts open; this process will occur repeatedly, but
the compressor cannot be started.
E. Compressor won‘!t stop
Sometimes, the compressor will run continuously(for several hours or
32
Summary of Contents for HRB-271
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