Hi,

I need to know if anyone know what is the standard procedure for whirl testiing of axial fan. There is a requirement to perform test for a minimum of 15 minutes at 125% of maximum rated fan RPM with air delivery of 10m3/s. The rated motor was sized at 115%. Will doing this requirement burn out the motor.

Anyone can help me out.............

I have never heard of the term "whirl testing" applied to fan overspeed test. Is this "Slang" terminology or a special test for this particular product? A 25% overspeed is unusually high, and a duration of 15-minutes is unusually long. So what are these unusual requirements for? If the motor is variable speed, then you also risk cooking the VFD controller and the motor. IF belt driven, then can the belts take the extra power? If these requirements are real, then I would like to learn about it.

Isn't maximum safe motor load determined by "full load amps" (FLA) times the "service factor" ?

I read somewhere that it is also called static pull test. A kind of performance and endurance testing of propellers (or other rotating devices) at various speeds and horsepower.

Regards,
Dyll

I am fully with Walt here. These texts makes me curious. Where in the world are such thoughts put in printing? Running 100 percent of spec is one thing. Can the system behind take or would suck suck the channels flat and blow compensators out, hmmmm?

For a centrifugal pump connected to a system that doesn't change (no change in valve position), power increases by speed^3.

I think a centrifugal fan is not too much different.

In that case, increasing speed by 125% would increase power by 125%^3 ~ 195%.

If motor was only 115% oversized at full speed, the motor would likely trip. Assuming protection is set properly, I don't think overheating damage to the motor is likely.

Yes, the system should be reviewed for mechanical effects of overspeed on rotating equipment and duct system as mentioned. But with proper review, it is my understanding that it is common for vfd systems to operate above base speed.

Why do they call it whirl test... one could guess that one of the purposes of the test is to check for resonance over a speed range up to 125%. But don't need a load to do that.