How to use Fan& Pump Motor Sizing and IEC Frame Sizing Calculator
- Enter Design airflow or flow rate and adjust the options as needed.
- Run the tool and inspect its results, evidence and limitations.
- Copy or download the result, then verify it against the actual website, source data or business records.
Try a concrete example
Airflow 5000 m³/h at 450 Pa with 68% efficiency direct drive has 0.63 kW air power, 0.92 kW BHP, and 1.06 kW with 1.15 SF, recommending an IEC 1.1 kW (1.5 HP) IE3 motor with 2.45A FLA, 6A breaker and 2.5 mm² cable.
How to interpret results
Applies fluid mechanical power P = Q × ΔP across the drive train, sizing to standard IEC 60034-30 ratings, computing full-load amps (FLA), and sizing circuit breakers and cables.
Frequently asked questions
Why is brake horsepower (BHP) significantly higher than air power?
Air power P = Q × ΔP is useful kinetic energy delivered to fluid. Impellers have aerodynamic blade losses, tip recirculation and bearing friction (efficiency 55%~78%). Shaft BHP must exceed air power accordingly.
Why must a service factor (SF) margin be added when sizing motors?
Grid voltages fluctuate by ±5%~10%, and cold ambient air increases air density, elevating motor load. An SF of 1.15~1.20 prevents nuisance tripping and motor winding insulation overheating.
How high is fan motor locked rotor inrush current (LRA), and how to size protection?
Direct-on-line (DOL) start inrush (LRA) is 5 to 7 times FLA for several seconds. Upstream circuit breakers must use D-curve miniature breakers or dedicated motor protection switches.
What is the efficiency difference between direct drive and belt drive?
Direct drive delivers 100% transmission efficiency. V-belts suffer from slip, hysteresis flexion and radial bearing load, lowering efficiency to 90%~93%. Direct drive saves thousands of kWh annually.