# Help Using LTSpice to Calculate Power Factor

#### cebucher

Joined May 27, 2012
6
Hello all -

I have a very simple power supply circuit and would like to use LTSpice to calculate the power factor. I can get the Average Power and RMS Values for these nodes, but not sure how to calculate.

Any help would be greatly appreciated.

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#### crutschow

Joined Mar 14, 2008
27,760
The power factor is the Real (RMS) Power divided by the Apparent Power (RMS voltage times RMS current without regard to phase between the two) averaged over one or more complete cycles.

#### cebucher

Joined May 27, 2012
6
The power factor is the Real (RMS) Power divided by the Apparent Power (RMS voltage times RMS current without regard to phase between the two) averaged over one or more complete cycles.

In this example, I can get from LTSpice the RMS Voltage = 120V and the RMS Current = 0.421A. However, LTSpice only shows the Average Power for the V1 Source = -25.556W (and integral is -2.3256J). But I am not sure how to convert to RMS Power.

Thanks.

#### crutschow

Joined Mar 14, 2008
27,760
You may have to export the individual calculated plot values to Excel, then do a numerical integration and calculate the RMS value over one period.

#### cebucher

Joined May 27, 2012
6
Would anyone have an idea of the approximate power factor from such a simple power supply?

#### crutschow

Joined Mar 14, 2008
27,760
According to this, page 6, the power factor for such a supply is about 0.7.