21
Malfunction
Possible
cause
Troubleshooting
04
Loud
fan
Buildup
of
deposits
on
impeller
Clean
the
impeller.
Impeller
worn
Replace
the
impeller.
Impeller
deformed
by
thermal
influ
‐
ences
Replace
the
impeller.
Defective
motor
roller
bearings
due
to
relatively
long
‐
term
impeller
imbal
‐
ance
Replace
the
roller
bearings
and
re
‐
balance
the
impeller.
05
Power
consumption
of
motor
too
high
or
ther
‐
mal
overload
on
motor
Ductwork resistance
too
low
Check
the
valve
positions,
throttle
the
air
quantity,
and
check
the
suc
‐
tion
line
and
device
for
leaks
and/or
open
inspection
hatches.
Water
level
too
high
Check
the
level
regulator.
Lower
the
water
level.
Defective
compensator
Replace
the
compensator.
Fan
running
in
wrong
direction
Reverse
the
motor.
Relatively
high
impeller
speed
(60
Hz
grid)
Check
the
frequency
and
replace
the
impeller
if
necessary.
Clogged
air
supply
pipe
of
motor
cool
‐
ing
system
Remove
the
blockage.
Clogged
exhaust
pipes
of
motor
cool
‐
ing
system
Remove
the
blockage.
Loose
or
defective
connection
collars
on
exhaust
pipes
Tighten
the
hose
clips
and
replace
the
defective
collars.
Water
level
too
high
Check
the
level
regulator.
Lower
the
water
level.
Motor
surface
heavily
soiled;
insuffi
‐
cient
heat
dissipation
Clean
the
motor
surface;
make
sure
that
the
cooling
fins
are
clean.
06
Fan
does
not
start
run
‐
ning
Drive
motor
connected
up
wrongly
Check
the
connection
and
reverse
the
direction
if
necessary.
No
switch
from
star
to
D
‐
connection.
Only
one
third
of
the
starting
torque
is
applied
for
the
star
connection.
From
a
certain
speed,
the
load
torque
of
the
impeller
is
as
large
as
the
motor
torque.
If
no
switch
to
delta
takes
place,
the
motor
never
reaches
its
final
speed.
Ensure
a
star
‐
delta
startup.
Insufficient
motor
protection
Check
the
cable
cross
‐
section/protection
features
and
re
‐
place
them
if
necessary.
Start
from
a
warm
operating
state
Excessively
high
starting
frequency;
allow
the
motor
to
run.
Starting
current
too
high
Ensure
a
star
‐
delta
startup
or
soft
startup
Drive
motor
defective
Check
the
motor
and
replace
it
if
necessary.
Phase
defect
Check
the
electrics.
