Power Factor Discussion

[Chris15]

David,

It would be really cool if you were able to compare the reality with some theory for me...

I've had excel do the maths of the harmonics on a 33% dimmed sine wave (ie. 33% duty cycle) and the graph is attached.
View attachment FFT of Dimmed waveform.pdf

Are you able to replicate it and see what the real harmonic plot looks like for a similarly dimmed state?

 

[DavidNorth]

David,

It would be really cool if you were able to compare the reality with some theory for me...

I've had excel do the maths of the harmonics on a 33% dimmed sine wave (ie. 33% duty cycle) and the graph is attached.

Are you able to replicate it and see what the real harmonic plot looks like for a similarly dimmed state?

Hi Chris,

I'm sorry to say I had very little time today and my backup guy is out as well. I did run a quick check and have these pics. Give me a little more time and I'll get you some much better graphs. View attachment 7585View attachment 7586

Can you explain the axes values on your FFT plots, please?

Thanks,

David

Are you able to replicate it and see what the real harmonic plot looks like for a similarly dimmed state?[/QUOTE]

 

[Chris15]

Sure, tonight when I get home and have a bit more time.
Let's be clear though - There is every chance my graphs could be wrong...
X axis is frequency in Hz (This is naturally modelled at 50Hz, South Planet and all that...)
The Y axis is a logarithmic magnitude plot and it's here that I'm not convinced... I shouldn't be seeing any even harmonic components because the wave is obstensibly cosinusoidal...