Novenco ZerAx axial fan types AZL-AZN-AZW
– Installation and maintenance
13 of 30
5.2 Motors with Y/
start
Set the relay for start of the fans to the
Start-up time from the technical
specifications from the AirBox
program. Alternatively, calculate the
value with the formula.
The motor torque can vary within the
below limits and affect the start-up
time.
5.3 Start-up procedure
Refer to the motor manual and the technical specifications from the AirBox program for specific
information and procedures.
Start-up procedure
1.
Start the fan.
2.
Check that no abnormal noises are present.
3.
Check that the vibration levels are
acceptable.
.
4.
Check that the fan operates normally after
30 minutes of operation.
5.4 Air volumes for free inlet fans
For fans with measuring pipes and free inlets, the air volume can be calculated as shown below.
The measuring pipes are optional accessories and fitted close to the fan inlet.
The below formula gives the air volume in m
3
/s. Multiply by 3,600 to convert to m
3
/h, or by
M
s
: -15% to +25% of
catalogue value
M
k
: -10% to 0% of
catalogue value
Calculation of start-up time
t
s
=
t
s
: Start-up time [s]
P
: Rated output of motor [kW]
P
v
: Required power of fan [kW]
n
: Fan speed [RPM]
: Ratio between the start and the nominal
motor torque
: Ratio between maximum and nominal
motor torque
I
v
: Polar moment of inertia for fan [kgm
2
]
I
m
: Polar moment of inertia for motor [kgm
2
]
0.24 n
2
I
m
I
v
+
10
4
P
M
s
M
-------
M
k
M
--------
P
v
P
------
–
+
-----------------------------------------------------------------
M
s
M
-------
M
k
M
--------
The fans are designed for continuous
operation. The below kinds of
operation may cause fatigue breaks
in the rotors and endanger people.
•
Operation in stall area, i.e. with
counter pressure that pulsates -
called pump mode
•
Operation with uninterrupted
and repeated starts and stops
•
Uneven flow velocity through
the fans
Ask Novenco if in doubt.
