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nobody talking about switching PS wasting power on input filter caps?

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radiolistener:

--- Quote from: emece67 on August 24, 2019, 11:48:43 pm ---No matter what effects such energy from the capacitor may have on the generator or the mechanical source, after a while such effects will be perfectly cancelled by an equal amount of energy flowing in the other direction

--- End quote ---

for AC it matters, because power will be returned with some time lag. AC source will be changed after this lag, so the result will depends on how new AC value will be different from a lagged value. Lagged value will change load impedance on AC source and the new impedance will depends on this time lag and AC frequency.

BTW, you can connect 1000 Farad capacitor to AC alternator and it will be almost the same as short circuit. I'm suspect that idea that AC alternator with such capacitor will rotate almost forever (as claimed by soldar&co) looks not realistic.

Brumby:
1. Whether the capacitor is a microfarad or a megafarad makes no difference to the principles involved.  It just changes the number in the arithmetic.  Please don't try and obfuscate the discussion with such irrelevant extremes.

2. Any talk - or perceived talk - of concepts that might lean towards "perpetual motion" here is based on IDEAL components.  In the discussion I have read, such statements are, indeed, correct.  These must also include completely isolated systems and every other requirement for an ideal system - including not making any measurements.  IN PRACTICE, we DO have losses, so the "perpetual motion" viewpoint is completely irrelevant within this discussion.  However, IN THEORY, such discussion with the assumption of ideal components, is correct when we wish to consider the fundamental processes in play.  In fact, we really need to consider the system with ideal components in order to get a grasp on those principles.

3. I am concerned about the use of the word "consume" by radiolistener.  It infers a loss, whereas I get the feeling it needs to be interpreted differently - more along the lines of an energy transfer function.

Just my 2 cents.

radiolistener:

--- Quote from: Brumby on August 25, 2019, 01:22:33 am ---1. Whether the capacitor is a microfarad or a megafarad makes no difference to the principles involved.  It just changes the number in the arithmetic.  Please don't try and obfuscate the discussion with such irrelevant extremes.

--- End quote ---

Updated: I have thought and it looks that I was not right, we cannot compare short circuit with large capacitor. These things with AC alternator looks very strange, needs to learn it more deep and make some experiments :)



--- Quote from: Brumby on August 25, 2019, 01:22:33 am ---2. Any talk - or perceived talk - of concepts that might lean towards "perpetual motion" here is based on IDEAL components.

--- End quote ---

I understand that. We assume that there is no heat loss for such "perpetual motion". But I still don't believe that it will keep rotation with any capacitor.

james_s:
You've got it backwards, returning energy to the generator makes it turn more easily because it acts as a motor, not harder to turn.

At this point I'm starting to think you're just trolling because any EE or textbook will tell you that you're wrong and yet you continue to argue against it. Just what is it you think you know that engineers do not?

If you're not trolling then you're wrong, you don't understand it and you're not trying to understand it, do you just enjoy arguing?

james_s:
Perpetual motion cannot happen because even 0.00000000000000000000001% loss will eventually deplete the system. When talking about a small increase in I2R losses it's not really significant until you get to a large scale like industrial settings and those historically have been heavy on inductive loads, hence the capacitors added to correct the power factor.

Nothing is perfect and there always are some losses but they are small. A capacitor that caused 500W of apparent power to flow might result in a few watts of energy wasted in heating the wires. It is this I2R loss that will result in a very slightly higher mechanical load turning the generator but this is negligible, nowhere near what you would calculate from apparent power.

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