4
NovAx™
axial flow fan types ACN-ACW ATEX and ACW EX
fan inlet.
The ACN-ACW ATEX and ACW EX fans
are prepared for circular duct
connections on the inlet and outlet sides.
Flanges for type ACN comply as
standard with Eurovent 1/2, and for
type ACW with DIN 24154 row 4.
Systems with higher vibration levels or
more high performance requirements
must be provided with expansion joints
between fans and ducts.
Connect the fans directly to ducts with
just one flange or as duct pieces with
both flanges.
4.6 Electric connection
Install fans with frequency drives in
accordance with the EU standard for
electromagnetic compatibility (EMC),
with the frequency drive manufacturers
installation specifications and out of any
EX zones.
Shield and connect the fans electrically to
ground to eliminate interference and
protect the motor bearings and
windings.
Refer to the motor documentation for
methods to avoid impairment of the
mains power quality, among them
distances between supply and signal
cables. Methods may involve
installation of rectifiers, filters etc.
The installation and connection
to the supply network must be
done by authorised personnel
and be in accordance with current
legislation.
Connect the supply voltage directly in
the terminal box on the outside of the fan
casing. The cable run must be in
accordance with the EMC regulation.
Refer to the connection diagram in the
terminal box lid for information on how
to connect. See also the wiring diagrams
in the “Appendices” on page 9.
Refer to the motor name plate as well as
the order specification.
Only fans with steel hubs may
be run in reverse for short
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 operation increases the risk
of stall and shortens fan life.
The rotor must be completely
stationary, before restart of the fan for
directional change of rotation. It is
recommended to install a time delay
for this purpose.
Check that the rotational direction of the
rotor complies with the arrow on the
outside of the fan casing. Flick the power
briefly On, then Off. If the direction is
wrong, disconnect the main power
supply and check the connections.
For ATEX fans the below minimum
airflow rates must be kept to maintain
the ATEX temperature rating.
5. Start of operation
Fans fitted with frequency drives must
have the control unit set up, before start
of operation. Refer to the Novenco
document “Configuration of frequency
converters for Novenco fans”.
Perform the below steps every time the
fans have been stopped.
5.1 Before startup
Check the fans and installation location
in accordance to the below checklist and
correct and improve the conditions as
necessary.
Checklist
•
Safe operation
The blade clearance must be
minimum 0.1x motor shaft
diameter (min. 2 mm, max. 13 mm)
all around the rotor circumference.
The axial distance between the
rotor hub and stator must be min.
3.5 mm.
Wire guards should be mounted on
the inlet and outlet sides.
•
Clean ducts
The fans and duct connections must
be clean and free from tools and
objects that can affect the airflow.
•
Electric connections
The electric connections must be
correct and in accordance to the
prescribed requirements. Flick the
fan power briefly On, then Off, to
check the rotational direction of the
rotor.
5.2 Motors with Y/
Δ−
start
Set the relay for start of the fans to the
Startup time from the technical
specifications from the AirBox program.
Alternatively, calculate the value with
the below formula.
Figure 6.
Optimum installation space
Figure 7.
Reduced installation space
Figure 8.
Fan with inlet cone and wire
guard installed on duct
3 x D
>
3 x D
>
½D
r
>
D
>
D
>
D = Fan diameter
Built into duct
Free inlet
D
>
D
>
½D
r >
½D
>
D
>
Built into duct
Free inlet
D = Fan diameter
Figure 9.
Installation in duct
Motor size
-71
-80
-90
-100
Flow [m
3
/s]
0.07
0.09
Motor size
-112
-132
-160
-180
Flow [m
3
/s]
0.11
0.21
0.47
0.54
Motor size
-200
-225
-250
-280
Flow [m
3
/s]
0.99
1.35
1.47
2.68
Table 3.
Min. airflow rates for ATEX fans
