4
the fan casing (see fig. 8). Connection is
made according to the connection dia-
gram in the terminal box cover.
Check the fan rotation direction once the
motor is connected. Do this by briefly
flicking the fan power on and off. It must
comply with the arrow on the fan casing.
If the direction is wrong, disconnect the
main power supply and check the con-
nections.
Reversible fans must be fitted with time
delays to allow the rotor to become sta-
tionary, before reversing the direction.
4.6 Thermal motor protection
The motor may have thermal protection
(optional accessory) in the form of a ther-
mistor or bimetallic sensor.
If the thermal protection is set to switch
off at unexpected temperature rises, it
must be connected to the security sys-
tem. The system must identify if the mo-
tor is working on emergency duty or not.
Alternatively, leave the thermal protec-
tion disconnected.
5. Start of operation
5.1 Before start-up
After installation of the axial flow fans
their correct installation, operation and
interaction must be established through
an approval test.
The person responsible for the operation
of the system must take the initiative for
this test.
The approval test must be confirmed by
the person responsible for the operation
of the system and the documentation
must be kept and produced whenever
asked for.
Prior to start of operation check that the
fan and duct connections are clean and
free from tools and foreign objects.
Also, check that the electric connections
meet the prescribed requirements, that
wire guards fitted on the fan inlet or out-
let side are correctly mounted and that
the direction of rotation of the fan com-
plies with the arrow-plate (check by
short-time operation).
5.2 Motors with Y/
Δ
starting
The relay must be set to the calculated ti-
me.
5.3 Start-up procedure
• Start the fan
• Check that no abnormal noise is
present.
• Check that the vibration level is
acceptable. The vibration level at
the fan operating speed must not
exceed 7 mm/s RMS, measured
radially at 2 points, 90º offset and at
the free shaft end of the motor.
Otherwise, the fan must be
balanced. Operation at vibration
levels exceeding 11 mm/ s RMS* is
not allowed for fixed fan positions.
Operation at vibration levels
exceeding 18 mm/s RMS* is not
allowed for fans on support frames
or anti-vibration dampers.
* ISO 2954, Requirements for
instruments for measuring
vibration severity.
• After 30 minutes of operation check
that the fan operates normally.
6. Maintenance
Keep the NovAx ACN-ARN fans in
good operational condition to ensure
satisfactory function and service life.
6.1 Before maintenance
When the fan is out of operation for rea-
sons of inspection or maintenance, the
electric system must be switched off and
protected so that the fan cannot cut in.
6.2 Fan casing
The fan casing requires only ordinary
cleaning.
Painted casings should be checked regu-
larly and surfaces repaired if necessary.
6.3 Rotor
From the factory, the rotor is supplied
with blades adjusted to the pitch corre-
sponding to the desired operating point
(pressure and airflow) at the fan speed in
Important:
Only fans with inner hubs
of steel may be run in
reverse. Reversible
operation increases risk
of fan stalling. If the fan
stalls, the service life is
shortened.
Important:
The NovAx fans can run
in reverse for shorter
periods at speeds up to
the max. allowable of
normal direction. The
airflow is reduced to
approx. 50% of normal for
the same system
resistance. The pressure is
reduced to 25%.
Reversible fans must be
fitted with time delays to
ensure that the rotor is
completely stationary
before reversing
direction.
Running the fans in
reverse increases the risk
of stall and shortens fan
life.
Important:
The fan is designed for
continuous operation.
The following kinds of
operation may cause
fatigue breaks in the rotor
and endanger people.
-
Operation in stall area -
operation with
pulsating counter
pressure - called pump
mode
-
Operation with
repeated starting and
stopping.
-
Uneven flow velocity
through fan.
If in doubt Novenco
should be contacted to
assess fan suitability.
Figure 7. Dismounting and mounting of axial flow fan
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08
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