Start 5 Fan Systems 5 Control of fans and fan systems

Control of fans and fan systems

Fans are often controlled with a frequency converter, which gives the fan a wider performance range.

When controlling with a frequency converter, the user must take into account the fan’s resonant speed and ensure that the fan is not at these frequencies for longer periods.
These resonant frequencies must be blocked in the control so that they are passed quickly.

When checking vibrations due to resonance, it is important that the vibration amplitude is measured on the motor and not on the fan cover.

At low speeds, i.e. at low engine torque, care must be taken so that the fan cannot be stopped by an opposing air current, which can lead to overheating of the engine.

Change of direction of rotation and free rotation (so-called “Wind milling”) of axial fans can create large current pulses that can cause disturbances or wear on connections and electrical networks. These pulses can also damage impellers and electric motors.
Therefore, a sufficient deceleration time must always be allowed before changing the direction of rotation.
In case of major problems with free rotation, the recommendation is to install a motor brake that releases just before the motor stalls.

When a “star-delta” start is used, the changeover must not be done too early, this to avoid large current pulses.

Du kanske också är intresserad av…

Smoke fans and smoke ventilation: A life-saving function

Smoke fans and smoke ventilation: A life-saving function

What is important to consider when choosing smoke ventilation and what is a smoke fan? This is what we will try to clarifiy in this article. Why is smoke ventilation needed? Smoke ventilation plays a critical role in the fire protection of buildings and public spaces....

Fans for ATEX (Explosive environments)

Fans for ATEX (Explosive environments)

It is not always easy to understand the entire ATEX directive and what applies to your particular application.As part of the fan hub training, we have a short course about what ATEX is and what need to be taken into consideration in connection with the installation of...