How the external rotor motor works
Most fan motors spin an inner shaft; the external rotor motor turns the shell around the stator instead. On the SYB fan, the centrifugal wheel fixes directly to that outer rotating shell - the impeller, rotor and shaft effectively become one rigid part. Known as the SYB, this external rotor motor direct-drive centrifugal fan sits in Midi Industrial's central air-conditioning range, aimed at cabinet builders who value a short, stiff drive line inside a compact AHU section.
What that means on site
Because wheel and rotor are bolted together directly, there is no belt, no sheave and no separate bearing pedestal to align. The whole fan sits closer to the air path, which saves depth inside the casing. The assembly balances as one unit at the factory, so you do not dial in pulley alignment during installation. Maintenance over the years stays light: a periodic check of the motor and the wheel, rather than belt tension checks and spare belt stock. Diameters from 200 to 500 mm cover a fair spread of packaged units.
Where it's used
The SYB lands in central air-conditioning units, air handling cabinets and indoor ventilation boxes for offices, hotels and industrial workshops. If you are specifying a low-maintenance internal fan for a unit that runs long shifts, this direct-drive external rotor layout is worth comparing against a conventional belt-driven wheel. Send your airflow and pressure target, and Midi Industrial will match the diameter and motor to the duty; HVAC fan manufacturers commonly buy it as an internal module for their own cabinet ranges.
Impeller Diameter: 200-500mm
Air Volume: 1000-20000 m³/h
Pressure: 0-600 Pa
Drive Type: Motor direct drive