Calculating Fan Power Using an Ohm Meter: Is it Possible?

[pixel01]

Hi guys

I suddenly think of a question. In my home, there's a standing fan which is old so I cannot see the nominal power on the label. With a ohm meter, can I identify the power of the fan? The meter can measure resistance R, potential U and current I of an AC power supply.

 

[FredGarvin]

Current and voltage are what you need to measure.

 

[Mech_Engineer]

P = I^2 * R

 

[pixel01]

I am afraid those above formulae can only applied for the pure resistance appliances such as heaters or filament bulbs. The fan is not the case, it has inductance.

 

[sstone]

$$P = I \cdot U$$ would be ok.

 

[zoki85]

$$P=UIcos\ \phi$$ even better.

 

[pixel01]

thanks all for posting here. Then my question is how can I identify the phase lag angular phi with only a VAOhm meter?

 

[FredGarvin]

You would need an o-scope or something like a hand held Fluke meter.

 

[Mech. Engineer]

Power=I*U

this will give you the power produced by the motor

but it will not give the real power of the fan...

which is power=Tw

fan power will be a little less than motor power and this due fraction(energy conv.)