Generators and switch mode power supplies.

Meaning you didn't understand it.

Didn't I say that it varied? Oh yes, I did. But you snipped that because had you not done so, you comment would have looked as silly as it actually is.

Yes. Your point being?

Sylvia.

" Stupider than Anyone Else Alive "

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Obvious to anyone but a

DEMENTED TROLLING PSYCHOPATH

F*ck OFF !!!

...... Phil

I said "mainly", which I stand by. Increasing the current with a proportionate decrease in the time it flows produces only a modest increase in average power dissipation, because the forward voltage increases only slowly (with a logarithmic character) with current.

Sylvia.

" Much Stupider than Anyone Else Alive "

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Obvious to anyone but a

DEMENTED TROLLING PSYCHOPATH

F*ck OFF !!!

...... Phil

That assumes that competing products are similarly affected, which isn't always the case.

A computer PSU ( without PF correction) might like a modified sine better than a real sine.

What is the conduction angle of the bridge rectifiers on a simple PSU when operated on a modified sine as compared to a real sine wave? It is possible that the RMS current is LOWER on the modified sine because the rectifers can conduct for the full time of the flat top of the square wave. In the case of the sine, they conduct for only a breif pulse at the tip of the sine.

I don't think the answer is as simple as some of you are saying..

Mark

In their right place, they're fine. What I disapprove of is arbitrary legislation to force people to buy stuff they don't want.

Hope This Helps! Rich

A power supply can be designed with harmonic correction. Then that same circuit may be 'forgotten' when the same supply is sold in Australia. Harmonic suppression is required in Europe. A same supply without that harmonic compensation is sold elsewhere with a slightly different model number.

A power supply manufacturer may not need to meet local requirements. A computer that must suppress harmonics is the responsibility of the computer assembler - not of the power supply manufacturer. Therefore many power supply manufacturers dump into the market products that violate local standards. He is not responsible. The computer assembler who buys his supplies may be responsible for meeting those code requirements. Unfortunately many computer assemblers have so little technical knowledge as to not even know what harmonics are.

I have no idea what that market discussion has to do with harmonics. I believe the original question was about a computer operating on a generator. Computer power supplies must be so robust as to make those square waves (modified sine waves) irrelevant. But again, did a power supply manufacturer bother to meet industry standards? Or simply forget some components to sell a cheaper supply also for higher profits?

There is a half sine shaped current pulse that lasts 2 to 3 mS.

..... Phil

Seems to me it's longer. As Mark has observed, it will conduct for as long as the modified sine wave remains high - though pulsed as the switcher turns on and off.

That said, the current will consist of an initial high pulse to recharge the capacitor, followed by low pulses that average to the short term PSU output.

The RMS current thing is a red herring anyway. While it's well enough defined, it has significance only for current passing through a circuit element that behaves like a resistor, which a rectifier doesn't.

Depends on your definition of brief, Phil.

So you do not consider me to be simple.

Sylvia.

The alternative is for the electricity supplier to impose contractual conditions requiring that the customer not impose singificant harmonic loads. If the customer fails to comply then they could be disconnected.

The customer, of course, wouldn't have a clue about this, and violations would be frequent.

Must simpler if the customer can't buy non-compliant gear in the first place.

Sylvia.

Yes, pushing the costs to the public is much more effective. Pollution and environmental degradation are classic forms of this.

Also correct.

Agreed. Producers in Europe and USA have the highest costs, sloping downward to elsewhere including South American nations, China, India and finally African nations. These have varying amounts of environmental laws, labor laws (which impacts labor costs), and other taxes and benefits. It is quickly clear why so much off-shoring goes to China and India and a lesser amount to other places.

But there are people who want it (the utilities). Moreover since it tends to minimize electric distribution infrastructure costs it can be related to something residential customers can understand, their electric rates. Trade-offs like this is part of what makes regulation complex (some find thinking on these things fun, they are called policy wonks).

It's an equity issue. Why should consumers who don't use high power SMPS (mainly in computers) subsidise those who do?

Sylvia.

When unloaded, my UPS produces pulses that are of the same length as when it's loaded, but there is a significant downward slope to top of the positive going pulses, and upward slope to the bottom of the negative going pulses.

Sylvia.

Like things that don't catch fire? Like cars with turn signals? Like grounded appliances? Like UL-tested outlets? Like safe and efective drugs?

John

Don't the power companies have something like a power factor/harmonics surcharge? It seems that would be the sensible thing to do, which is probably why the bureaucrats can't grasp the concept.

Thanks, Rich

Apparently, the majority of the sheeple are too lazy/stupid to not burn their own house down without some nanny state lording it over them.

Thanks, Rich