MVA 02 rev 5 - December 2017
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7
AXIAL FAN OPERATING MALFUNCTIONS
7.1
Most frequent malfunctions
The following chart lists the main problems that may be encountered:
PROBLEM
CAUSE
SOLUTION
Fan does not start
No electrical connection
Check
that
the
motor
and/or
command inverter to the electrical
power supply line and is correctly
powered
Motor malfunction
Check internal connections and motor
components and replace if necessary
No connection between command
inverter and motor
Check for correct connection between
inverter and motor
Command inverter malfunction
Check internal inverter circuits and
components and replace if necessary
Power absorption lower than design
value
Rotation speed too low
Increase rotation speed
Impeller partially blocked
Eliminate obstruction
Resistance pressure of system lower
than design value
Check the resistance pressure value
of the system
Fluid density lower than intended
value
Check the fluid density value
Incorrect blade angle
Increase blade angle
Power absorption higher than design
value
Rotation speed too high
Reduce rotation speed
Resistance pressure of system
greater than design value
Check the resistance pressure value
of the system
Openings or ducting partially blocked
Eliminate obstruction
Check the position of adjustment
organs
Pre-rotation of air in opposite direction
to fan rotation
Check minimum installation distances
(paragraph 5.1.1)
Fluid density higher than intended
value
Check the fluid density value
Power supply to motor with voltage
lower than shown on identification
plate
Check for correct voltage of power
supply to motor
Defects in motor windings
Check for correct motor operation
Incorrect blade angle
Reduce blade angle
Insufficient pressure
Rotation speed too low
Increase rotation speed
Fluid density lower than intended
value
Check the fluid density value
Air flow greater than intended value
Check the resistance pressure value
of the system
Pulsating operation
Instability of air flow
Check operating field envisaged by
operating curve
Fluctuations in flow due to other fans
operating in parallel
Check for correct installation on
system
Intake air turbulence created by
system near intake opening
Check minimum installation distances
(paragraph 5.1.1)
