diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Everything Else (http://www.diyaudio.com/forums/everything-else/)
-   -   Power factor calculation (http://www.diyaudio.com/forums/everything-else/97889-power-factor-calculation.html)

Netlist 11th March 2007 03:35 PM

Power factor calculation
 
How to calculate the ratio of resistive and reactive load if the impedance/resistance is not measurable?
http://www.ibiblio.org/kuphaldt/elec...html#02216.png

As a practical example, Id like to measure the cos(phi) of an energy saving light bulb which states to consume 8W but measures 230V * 0.057A = 13.1W.
Of course, believing the manufacturer is the easiest, 13.1W 8W gives a power factor of 0.61 but I'd like to verify.
Out of circuit, the bulb has an infinite resistance probably caused by the internal ignition circuit.

/Hugo

sreten 11th March 2007 03:59 PM

Hi,

Said bulbs have a complex supply / ignition circuit.
You cannot derive the power factor from that simple formula.

Only way I know of is a small additional resistor and an oscilloscope.

:)/sreten.

Netlist 11th March 2007 04:30 PM

Say a 10ohm resistor in series and go from there?

/Hugo

sreten 11th March 2007 05:11 PM

Hi,

Yes. With an oscilloscope you can then see the current and
its relationship with input voltage. May not be continuous.

:)/sreten.

Netlist 11th March 2007 05:21 PM

Thanks.
Would there be a way to compensate these bulbs for a higher power factor. I calculated a 457F (!) capacitor would bring the power factor close to 1. Apart from the fact that its rather silly to do, I'm trying to get a grasp of the basic math.

/Hugo


All times are GMT. The time now is 02:24 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio


Content Relevant URLs by vBSEO 3.3.2