Quote:
Originally Posted by StirCrazy
nope this is not how it works
here is a simple explanation of PF I found
"Power factor is the percent of electrical power that does work. Resistive loads, such as lights and heater elements, always have unity (1.0) power factor; all power is used for work. Motors, because they are essentially large inductors, lag current and cause power factor issues. A motor with a .85 power factor uses 85 percent of the power for work. 15 percent is wasted.
For example, a 480VAC, 10HP motor with a 1.0 power factor uses 10.6 amps to run at 10HP. Lowering the power factor to .8 requires the motor to consume 13.2 amps to produce that same 10 HP."
I read up on this years and years ago and can talk about it all day (well maybe not all day) but it is hard to sit and type it out, hence the simple explanation I found. we used to be realy concerned with PF with lights to get the efficiency.
you if you have a pump that is rated at 120 watts but has a power factor of .6 in reality it will use 200 watts to do the work. the extra 80watts are lost through ineficient circuts, heat, ect... so when the power company bills you you are billed for the 200 watts. this is why the hydro companies have rebates for big business to upgrade to high PF equipment, it lowers the demand on the grid.
Steve
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Ill chime in once more to clear up this misinformation. in your example, "200w" is actually 200VA. apparent power is measured in volt-amps. in a power triangle it is the hypotenuse. the 120w is correct, and is the horizontal side of the triangle. the one no ones talked about yet is the vertical side which is reactive power and its measured in VARs or volt-amp reactive. The power factor is a ratio between apparent power and true power. you are only charged for the true power used, which is the watts. that is the current that is in phase with the voltage. reactive power leads or lags the voltage, and isnt measured by residential meters. in this example, you will be charged for 120w NOT 200w.