Power factor with CFL!

I was bored and was playing with one of the plug in monitors which measure the amount of power your fridge or freezer uses over a set time.

I just wanted something handy to plug in and the desk light was handy. Then I looked at the power factor 0.87 and my thoughts are should not that have been corrected in the lamp.

It's an 11W Ikea lamp which actually shows as drawing 8W screw fitting E27 so nothing handy I can replace it with to see if just an odd bulb or is there is generally no correction with CFL.

A 0.2 μF capacitor would not cost much and I would have expected it to have been fitted in the bulb not having to be added external.

I know with standard florescent tubes we add the power factor correction in the fitting but with a E27 it could have standard bulb or LED as well as CFL so seems odd.

Maybe it was fitted and it has blown. In the main all my table lamps are now LED and either SES or BA22d so nothing to swap it with to test.

A few comments.....

Firstly, how accurate is your 'instrument' down at 8W? If this device is designed to measure upto 3000W (ie 13A ) its a big ask for it to be accurate at 11W ....

Let's say its accuracy is +/- 5% then the reading is only 5% * 3000 = +/- 150W

Secondly, a lot of the economy 'power' meters only measure current and assume the voltage so their math is off to begin with

Thirdly, the CPL is switch mode based so it doesn't draw a sinusoidal current - it will only draw a current 'pulse' at the peak of the mains waveform (when the mains voltage is > the voltage remaining in the reservoir capacitor). This leads to a current which is very harmonic rich and tends to confuse the cotton socks off anything other than a true RMS meter.

Fourth, the pf of the CPL is almost certainly leading not lagging due to the capacitor in the power supply.....so adding another would make the problem worse not better.

My own observations are that the pf of the CPL is very poor, and, although it might have wider implications on the distribution system, as a domestic customer it makes no difference whether the power factor is 1.0 or 0.1 .... I only pay for the real power component so it doesn't cost me any more to run it.


Adrian

AdrianUK said:

... pf of the CPL is almost certainly leading not leading ...

Click to expand...

Minor typographical correction required, I believe (why do fingers so often disobey the brain's instructions?!!)

Kind Regards, John

JohnW2 said:

AdrianUK said:

... pf of the CPL is almost certainly leading not leading ...

Click to expand...

Minor typographical correction required, I believe (why do fingers so often disobey the brain's instructions?!!)

Kind Regards, John

Click to expand...

Ooops! Corrected, Thank You