rated power on motor does not stack up?

[case-sensitive]

I found this fan, brought it back to life. The rated power is 250 W @ 240V and 2 A, which would get a power factor of 0.5, thought it has to be at least 0.75 or so?
I measured 540 W. The air velocity is about 20m/s, it should do 600L/s. But with wind energy formula and surface not know one could essentially calculate any power output between 80 and 900W, no idea, if the 250W mean the mechanical power output in terms of air moved?

Thanks for your ideas,

case

 

[crutschow]

The Watts is likely the input power, not the output power which probably is 75-80% of that.

How did you measure 540W?

 

[case-sensitive]

ok, 560 Watt. Still way off the 250 W on the nameplate.

 

[ronsimpson]

Is the motor hot?
I think it is turning slow and thus pulling too much power.

 

[case-sensitive]

will buy a tachometer, see what it says.
With the run capacitor the motor is 4 poles, so should run at 1500- rpm.
Without the cap it measures this (see picture) which is even worse. Would run as 2 poles then I suppose.
Its Australia, mate, they are sometimes not that fussy, 1km is a felt km, could be 100m walking or 3 km if by car ,-) Was looking for a toilet, it said 500 m or so, so I walked 500m then started looking. Could not find it, missed it at 150m, found it on my way back.

 

[Mr RB]

250W is likely its rated output (shaft) power, ie it's a 1/3hp rated motor.

240v at 2A sounds like typical running specs, and you seem to be overloading it quite a bit at 560W consumption (like Ronsimpson said).

 

[case-sensitive]

could not see, how, its a fan, free running. The only possibility is, air intake is slightly blocked. Plus does not have back pressure, no duct attached.
Or the capacitor as on the nameplate is wrong, reads 4uF run cap. And thats what I put in. Power factor is pretty good though.

edit: hooked up a 6m duct. If it lays flat, the air intake is partially blocked. Put it on some FC sheet, it kind of sucked it in, so it restricted the air intake. Now I got my 2 amps:

This would be plausible, because normally there is an air filter on the inlet. No idea, how much pressure drop it would generate. Rated rpms is 1320, not 1500. Interesting, that the more I block the air inlet, the less current it draws.

motor reaches 47 centigrade, stops there. On a 30° C day.


to get 250 W air movement need 20 m/s in a 10 inch duct, which would be 1000L/s.
Rated at 600L/s its 12m/s in a 25 in duct, or 50W.
measured between 16 and 20 m/s