# Re: PFC = power factor capacitor?

```PFC = Power Factor Correction

ESR = Equivalent Series Resistance.   Consider a real capacitor  as a ideal
capacitor and a resistor in series.  The ESR is the value of the resistor,
and is separate from the impedance of the capacitor.  It isn't the leakage,
but is more a way to represent the loss of the dielectric in an application
where you have AC current flowing through the cap (as in a filter,
typically).

The ESR will vary as a function of frequency (typically getting bigger as
you go higher in frequency).  It also dissipates power.

Here is an example: Say you have a 0.01 uF cap with a 10 ohm ESR in a tank
circuit at 100 kHz at 10 kV.  First, figure out the impedance of the cap at
the frequency: (X= 1/(2 *pi*f*C) = 159 ohms).  Now figure out what the
current is (I = E / Z where Z = 10-j*159  (a bit of complex math)) I = 3.9 +
j*62.6 mA....

Finally, figure out how much power is being dissipated in the capacitor.
You only need to consider the ESR because the ideal capacitor dissipates no
power...  I^2*R = 0.152 Watts

You'll also see "loss tangent" which is another way to give the same data.
It is essentially the ratio of R to X, or about 6.3 percent in this case

-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Friday, February 11, 2000 1:45 AM
Subject: PFC = power factor capacitor?

>Original Poster: Harvey D Norris <Tesla4-at-excite-dot-com>
>
>I am taking a guess at this latest abbreviation, it took me months to learn
>that ESR meant equivalent series resistance in a capacitor. Does this mean
>the ohmic resistance eqivalent to its capacitive reactance? Or does it
>represent the resistance encountered as leakage current?
>Sure wish the posters could at least say what the letters mean once in a
>while. HDN
>
>
>
>
>
>Binary Resonant System
>http://www.insidetheweb-dot-com/mbs.cgi/mb124201
>
>
>

```