umm, checked what?
I was thinking just that, input filters can't correct this, not in any way that i know of. and I don't remember ever seeing or hearing about a PFC-corrected SMPS. so... I get it that it isn't any better anywhere else around the world?
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Anyone who thinks they have a nice clean sine wave at their panel hasn't checked it yet.
And you are correct, no input filter will correct this. This is a voltage drop problem. Peak currents drawn across a sinusoidal source with non-zero impedance will cause some degree of flat-topping. An FFT expansion of flat-topping looks like what has been shown. It should not be confused with noise or RF.
I have seen many advertisements and claims, made by designers, retailers and manufacturers that PFC is fitted.
But the questions remain:
PFC does nothing for induced distortion of the sinewave. It just correctes the power factor, that means keeps the lag between the voltage and current at a minimum. I would guess that ADDS distortion, since it is done with switched components too.
In US situation is better in residential areas because, due to bigger distances (land lots) and lower mains voltage, there are only a few consumers on the same transformer (4 houses max), and if the distribution is done underground (shielded cables), that filters somewhat the high-frequecy contend generated in the other houses. Sure, it remains the one generated in the own house, but it is better than having 40 apartments tied on a commun electrical bus that goes from floor to floor.
In EU, due to higher voltage mains, that can be carried further and smaller lots leads to one transformer can feed 10-20 houses in rural areas and up to 120-140 apartments in urban areas.
In US situation is better in residential areas because, due to bigger distances (land lots) and lower mains voltage, there are only a few consumers on the same transformer (4 houses max), and if the distribution is done underground (shielded cables), that filters somewhat the high-frequecy contend generated in the other houses. Sure, it remains the one generated in the own house, but it is better than having 40 apartments tied on a commun electrical bus that goes from floor to floor.
In EU, due to higher voltage mains, that can be carried further and smaller lots leads to one transformer can feed 10-20 houses in rural areas and up to 120-140 apartments in urban areas.
The PE143 normative is from 2001. It wasn't enforced in the past very seriously anyway. In US every electrical equipment that is sold comes with a FCC testing report. Whatever chinese gadget does not pass, it is sold at half price in other countries that care less about that and more about cheaper prices (for vendors, the buyers pay anyway the same)
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so there is a guy testing for FCC compliance whenever a laptop charger bought on eBay enters the US, right? and each and every part made for US has active PFC, right?In US every electrical equipment that is sold comes with a FCC testing report. Whatever chinese gadget does not pass, it is sold at half price in other countries that care less about that and more about cheaper prices (for vendors, the buyers pay anyway the same)
zigzagflux's reply seems more credible.
Again, active power factor correction will draw current as a sine wave:
Power factor - Wikipedia, the free encyclopedia
Power Supplies, Why PFC, Pioneer Magnetics
You are confusing displacement power factor with true power factor. All power supplies, linear and SMPS, have pretty decent displacement power factor, which is phase angle between fundamental voltage and current. That's easy. Active power factor correction corrects true power factor and forces current to be drawn as if load was resistive.
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yes, we should define what PF means.
in my view it is the current-voltage delay. when the load is linear (made only of passive parts) the current will always have a sinusoidal waveform.
as soon as the sinked current is not sinusoidal I'm not sure how PF as defined above can apply.
and as was stated above, I find it very hard to believe that someone would design a switching phone charger that draws sinusoidal current.
in my view it is the current-voltage delay. when the load is linear (made only of passive parts) the current will always have a sinusoidal waveform.
as soon as the sinked current is not sinusoidal I'm not sure how PF as defined above can apply.
and as was stated above, I find it very hard to believe that someone would design a switching phone charger that draws sinusoidal current.
this is an useful read by Charles Hansen: http://conceptorg.com/techlibrary/PowerTechnology/AC_and_Audio.pdf
looks like most of the distortion (except the slanted tops and bottoms) is because of the generator.
I'd still like to know what causes those.
looks like most of the distortion (except the slanted tops and bottoms) is because of the generator.
I'd still like to know what causes those.
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The UK, most european and American mains has a huge generating network and thus inerta behind it. Some other areas are not as lucky, and have distributed generating sets.
Mains and its noise and what causes the effects seen is studied and the mains is monitered...
SMPS's are not the main problem, HVAC is and industry that uses harmonic drives etc.
|Dont forget you home supply is just one phase of the 3 phase distributed network.
Mains and its noise and what causes the effects seen is studied and the mains is monitered...
SMPS's are not the main problem, HVAC is and industry that uses harmonic drives etc.
|Dont forget you home supply is just one phase of the 3 phase distributed network.
good point, never thought about that.
would you please explain this? I'm not aware of the details of power distribution.
There are a few obvious errors in his document (audio guy reporting on power transmission) such as the generator step up typically being Y-delta when in fact delta-GndY is more common, but in general he is correct. But note, his claim is not that the generator produces the most distortion, in fact it is less than 1.5%. Most of the distortion comes from voltage drop across series impedance of line and transformers.
A 5/6 pitch generator feeding into a delta-Y transformer is nearly as perfect as you can get in high power generation. The generator is not the problem; voltage drop across series impedance is. It's not the 'obvious choice', it is the only correct answer. Not RF, not dirty power (whatever that is), not noise, not saturation. Simple voltage drop.
You can get particular and discuss the slightly changing value of impedance at each harmonic, but at the end of the day it's still voltage drop across impedance.
Mains distribution is interesting and quite complex. I did 8 years working in the design dept of a company that did Gen Set controllers. The guys that set the systems quite often explained the ins and outs of it all... A lot of it left be baffled. But what I do remember is the explanations of overall generating system inertia. Countries with distributed mains have numerous large generators on line and back ups, sudden changes in load are handled by the shear wieght of on line gens. Counries without such systems are developing smaller distribution networks, with localised generating stations, these are limited in the amount of power they can put out and are often small diesel or methane gen set farms, a sudden load will have much more effect on the network and thus the mains quality. It is similar to an amp having an adequate PSU to one having a BIG overated power supply, one may clip, the other wont.
Power factor correction is also important for generating eleectricity, if it isnt 1, then generated power is just being wasted, I cant explain it technicly, that was one lecture that went over my head, but I believe when PF is unity all the power generated reaches the load, when V/I are leading or laging each other power is being wasted in the system.
Hopefully Zigzagfluz can explain and correct if I'm wrong here, its not my field.
Power factor correction is also important for generating eleectricity, if it isnt 1, then generated power is just being wasted, I cant explain it technicly, that was one lecture that went over my head, but I believe when PF is unity all the power generated reaches the load, when V/I are leading or laging each other power is being wasted in the system.
Hopefully Zigzagfluz can explain and correct if I'm wrong here, its not my field.
This is the other "Charles Hansen" not the hi-fi equipment manufacture. While this "Charles Hansen" has been writing articles in Audio Amateur, Audio Electronics, AudioXpress magazine for at least 15 years, during the day he has worked as an electrical engineer since 1967. He has several patents in his field.
marce,
PF for industrial power eaters is, to my best knowledge, a different issue. large current consumption with <1 PF causes a lot of wasted power in distribution lines and they have to (literally) pay for it. anyone please correct me if I'm wrong.
I think there's some confusion floating about.
there is PF and the effects described above. it's undesirable because energy is wasted.
and there is what is shown in my first post. that's something else, can be related but not the same thing.
later edit: oh, I get it, there's literally two Hansen's
PF for industrial power eaters is, to my best knowledge, a different issue. large current consumption with <1 PF causes a lot of wasted power in distribution lines and they have to (literally) pay for it. anyone please correct me if I'm wrong.
I think there's some confusion floating about.
there is PF and the effects described above. it's undesirable because energy is wasted.
and there is what is shown in my first post. that's something else, can be related but not the same thing.
maybe Mr. Hansen himself which is a member here would care to join?
later edit: oh, I get it, there's literally two Hansen's
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