IMO AXC 2014 04

NOTE Risk of damage to the fan!
If the fan is operated outside the characteristic stated, there is the risk of unstable running
and inadmissible vibrations, even possibly its destruction.
Do not operate the fan outside the characteristic stated.
• Do not operate the fan outside the characteristic stated. This can happen in the case of a bad ow
or excessively high resistance in the system. The fan must run on its prescribed operating point.
• Fill in the attached commissioning record sheet and present it in the event of a warranty claim.
12 Operation
When operating the fan, pay attention to the operating instructions from the motor manufacturer.
Regularly check the awless functioning of the fan (free movement of the rotor, measurement of the current
consumption, check for possible vibrations and noises).
12.1 Speed-controlled fan operation
General:
Fans can be speed-controlled to reach the required operation point of the installation and user requirements.
Speed-control, maximum speed:
The speed specied on the name plate must not be exceeded.
Counter-measures in case of resonance frequencies:
Excitation of mechanical components causes resonance frequencies. Improper high oscillations and malfunc-
tions could be the result. This may damage impellers, shafts, bearings, housing parts or external components.
Excitation frequencies are caused by e.g. impeller, blade or motor rotations, blade rotational frequencies or
aerodynamically. If the excitation frequency nears or meets the resonance frequency of a component, reso-
nance oscillation may result in malfunctions. The exciter forces are affected by true running characteristics,
balancing situation, aerodynamic forces and damping characteristics of the components.
WARNING! Risks due to resonance frequencies!
Avoid continuous fan operation at speeds with increased oscillation values. These speeds must be skipped
or deactivated during operation. Make sure that these stages will be passed quickly during start-up to avo-
id transient oscillation and exceeding of the admissing oscillation of the resonance frequency. A permanent
oscillation monitoring is recommended to ensure a safe and continuous fan operation.
Take a close look on oscillation damages during fan inspection and maintenance. It is recommended to
change or increase the maintenance cycle to apply the operating conditions during normal operation speed.
In these cases, it is usual to start with short maintenance rates after commissioning. If no damages occur, the
rates can be changed stepwise to meet the specied maintenance rates from the operating instructions. This
decision has to be made by the installation owner.
Commissioning of speed-controlled fans
It is necessary to check out the fan for oscillations at all normal operation speeds during commissioning.
Oscillations on housing and bearing areas have to be determined and evaluated in accordance with DIN ISO
14694 depending on motor power and positioning. The admissible oscillation velocities can be requested
from Systemair.
Measurable oscillation velocities depend e.g. on following factors:
• positioning
• bottom section/foundation state
• ow conditions
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AX - 01.2013
Axial, smoke and heat exhaust fans, series AX