[Vwdiesel] ----( The Power Factor )
scameron at compmore.net
Mon Apr 18 19:48:22 EDT 2005
Power factor is so much like spark or injection timing, an analogy can be used.
Advance/retard, in the engine, with relation to TDC of piston. In A/C power,
current [amps] advance/retard related to top (TDC) of voltage waveform
As the voltage at the generating station approaches the peak of the cycle,
if the load at the other end of the line is capacitive (not very often) the
load will suck max amps brfore the cycle at the GS reaches peak. As the
cycle reaches peak, the capacitive load will be partly charged, and the amp
load will reduce as the cycle reaches peak.
Your hydro meter will record the "power" used at a little less than if the
load were resistive and the amp peak co-incided with the volts peak.
If the load is inductive (most common, cheap split phase motors etc,) the
amp peak will not be reached until the volt peak is already on the way down
the other side. (An inductor "resists" the initial flow of current, and
continuously with alternating current) Once again, the meter, using the volt
peak as the time benchmark to measure the amps against, does not extract the
full watts reading when the amp peak occurs on the way down.
This bugs the hydro co. because your meter shows less watts used than you
actually used, and they have to generate more power than they can charge you
for to supply your load..
If it's serious enough (industrial users) they make you pay for giant
capacitors to correct the power factor of your big inductive load.
More and more appliances are using "run" capacitor motors to save power and
run cooler.(Energy Star) The cheap split phase capacitorless fractionals run
hot and waste half the power in heat.
For 50 years, fluorescent lights have used inductive ballasts to control the
current through the tubes (An inductive ballast acts like a resistor, only
for alternating current) Every ballast had a capacitor built in (for a long
time containing PCBs) to correct the power factor. If that had not been
legislated, the measured power used by fluorescent lights would have been a
fraction of the actual consumption. This has now been superceeded by nifty,
noisey, high frequency switching power supplies with unity power factor.
[Can you hear the buzzzzz?]
Hagar, what's the power factor of those aluminum retorts up at Kittimatt??
The arcs have inductors to sustain them?
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