10/10/2026
A fan runs well during operation. But what happens when it stops?
In ventilation systems, a fan may continue rotating โ or even rotate backwards โ after shutdown if airflow from other fans or connected ducts drives the blades.
This matters when selecting and configuring a motor-drive system.
Three conditions deserve attention:
๐น The actual load โ Airflow and system pressure can affect how the fan behaves after shutdown.
๐น The stopping process โ The fan's inertia and external forces may influence its deceleration.
๐น The next start โ If the fan is still rotating, the drive's ability to handle a rotating motor and the application's restart requirements need to be checked.
For motor and VFD applications, reliable operation means looking beyond steady-state performance. Stopping and restarting conditions matter, too.