watt-meter

[Flight987]

If you have athree-phase ciccuit where a watt-meter reads 11,040 watts, a voltmeter reads 460 volt's, and the
power factor is 81%, how much current would be present in the circuit? This is from a Prac. test and I have the
answ. and have no clue on this one.

 

[david luchini]

11,040 watts/0.81pf = 13,629.63 VA.

13,629.63VA/460V/1.732 = 17.1 Amps.

 

[Flight987]

Why is it

Why is it

Why is it that we don't take VA/(460x1.732) =Amp's. Is it because we are using EFF.? I take what I just said
is that, that nothing is 100% EFF. I feel dumb to see such a simple fix. Could we take 11,040/ (460x1.732) x
.81 and get the same result? I will try that and then go back to look at your work.

 

[david luchini]

Why is it that we don't take VA/(460x1.732) =Amp's.

That IS what I did.

Is it because we are using EFF.? I take what I just said
is that, that nothing is 100% EFF. I feel dumb to see such a simple fix. Could we take 11,040/ (460x1.732) x
.81 and get the same result? I will try that and then go back to look at your work.

Efficiency doesn't enter into the equation. 11,040/(460x1.732x0.81) will be the same as my work.

 

[Flight987]

EFF.

EFF.

So I had it right, just did a little different math?

 

[Flight987]

Thier was no responce

Thier was no responce

There was no responce to the last post?

 

[Flight987]

Seem's Mike Holt

Seem's Mike Holt

Seem's that there are more way,s to Cal.
Thank's Curt

 

[Hv&Lv]

Here...
http://www.elec-toolbox.com/Formulas/Useful/formulas.htm