Author Topic: nobody talking about switching PS wasting power on input filter caps?  (Read 10747 times)

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Offline emece67

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #75 on: August 24, 2019, 11:33:11 pm »
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« Last Edit: August 19, 2022, 02:27:38 pm by emece67 »
 

Online radiolistener

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #76 on: August 24, 2019, 11:40:36 pm »
"AC source consumes power from the capacitor", this is a pure nonsense), that are not the same thing, this BS can be stopped.

AC source can consume external power the same as DC source.
 

Offline emece67

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #77 on: August 24, 2019, 11:42:32 pm »
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« Last Edit: August 19, 2022, 02:27:46 pm by emece67 »
 

Online radiolistener

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #78 on: August 24, 2019, 11:45:08 pm »
From the capacitor?

If capacitor voltage is higher than AC or DC source, why not?

Above you can find some screenshots from LTspice with example. AC source consumes power from capacitor. You can see it on the graph.
« Last Edit: August 24, 2019, 11:47:34 pm by radiolistener »
 

Offline emece67

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #79 on: August 24, 2019, 11:48:43 pm »
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« Last Edit: August 19, 2022, 02:27:55 pm by emece67 »
 

Online radiolistener

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #80 on: August 25, 2019, 12:34:34 am »
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

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.
« Last Edit: August 25, 2019, 01:12:48 am by radiolistener »
 

Offline Brumby

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #81 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.

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.
 

Online radiolistener

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #82 on: August 25, 2019, 01:34:58 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.

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 :)


2. Any talk - or perceived talk - of concepts that might lean towards "perpetual motion" here is based on IDEAL components.

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.
« Last Edit: August 25, 2019, 02:03:25 am by radiolistener »
 

Offline james_s

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #83 on: August 25, 2019, 02:54:37 am »
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?
 

Offline james_s

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #84 on: August 25, 2019, 03:07:57 am »
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.
 

Offline soldar

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #85 on: August 25, 2019, 08:30:15 am »
There is so much confusion in this thread. radiolistener, you are not listening.

Assume an AC generator directly connected to a resistor. The power supplied is in phase with the voltage.

Now we connect a capacitor in parallel with the resistor.

During the first quarter cycle the generator has to work harder because, besides the power being supplied to the resistor it is also charging the capacitor storing energy in it.  It is working double time.

During the second quarter cycle the capacitor is returning the energy which goes into the resistor and this means the generator has to work less. Whatever current is supplied by the capacitor is less current the generator needs to supply.

If you do not understand this you should not continue to argue. You should go back and study some more until you understand it.
All my posts are made with 100% recycled electrons and bare traces of grey matter.
 
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Offline capt bullshot

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #86 on: August 25, 2019, 08:55:11 am »
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 :)

In terse: Your general AC generator / motor (in German EE we don't use these terms, we just say AC Machine or Engine, regardless of whether it is used as Generator or Motor), will act as an inductor if you load it with an capacitor and vice versa. So the energy that is "consumed" back by the generator from the capacitor isn't consumed but stored in that inductor and than delivered back to the capacitor in the next cycle. Think of an LC tank, works the same way as one compensates inductive load by using capacitors. The amount of inductance or capacitance that the generators shows to deal with its load is determined by that nice term "Polradwinkel" (angular displacement in synchronous generators) - one can set this either by changing the excitation of the generator (think of power plants) or it just works implicit (think of small generators / motors).
And yes, if there weren't losses, a generator loaded by a capacitor would run infinitely, same as an unloaded generator would do. The capacitor doesn't make the generator run forever, slower or faster, indeed it wouldn't change anything (in the ideal lossless model).
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Offline soldar

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #87 on: August 25, 2019, 09:34:02 am »
People with a poor grasp of things tend to confuse concepts and there is where we end up with people saying they think they have found a free energy source.

Saying perpetual motion is not possible is only a way of saying any machine we build in reality is going to have losses. But ideally perpetual motion is possible and we can see examples which get pretty close. The planets have been revolving around the Sun for some time now and will continue to do it for the foreseeable future.

What is impossible is not "perpetual motion", what is impossible is any system which yields more energy than it has stored and is receiving. Energy cannot be created out of nothing. An ideal machine can only yield as much energy as it is receiving. It can store it, it can transform it but it cannot create it. You cannot get energy out of nowhere.

With an ideal inductor and an ideal capacitor we could build a resonant LC circuit which would resonate forever but we could not extract energy from that system without slowing it down.

You can imagine an ideal pendulum which will oscillate forever but you cannot extract any energy without slowing it down. The amount of energy you can extract rom any system is what was put into it in the first place. No more.
All my posts are made with 100% recycled electrons and bare traces of grey matter.
 
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Offline emece67

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #88 on: August 25, 2019, 10:46:07 am »
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« Last Edit: August 19, 2022, 02:28:05 pm by emece67 »
 

Online radiolistener

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #89 on: August 25, 2019, 11:18:26 am »
More nonsense, now the impedances vary with time  :palm:

 :palm:
Don't confuse "time delay" with "time". This is different things.
 

Offline soldar

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #90 on: August 25, 2019, 11:42:20 am »
Don't confuse "time delay" with "time". This is different things.

If there is anyone in this thread who is confused it is you and you would do well to stop posting and go do some studying and some learning and stop wasting our collective time.
All my posts are made with 100% recycled electrons and bare traces of grey matter.
 

Online radiolistener

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #91 on: August 25, 2019, 12:00:06 pm »
If there is anyone in this thread who is confused it is you and you would do well to stop posting and go do some studying and some learning and stop wasting our collective time.

As I see, all what you can is just insulting and talking that other peoples don't know anything. Probably many people insulted you and talked that you don't know nothing, and it seems that they said truth, because it hooked you, and now you're trying to insult other in the same way for revenge.  ;) I'm really sorry you were so unlucky in life, but I cannot help you with that.

Your words is nothing for me, because it cannot be applied and do not matter. So, I don't care what is your thoughts. Is it possible to take offense at the donkey who kicked you?

May be I'm interested to discuss about AC alternators, because I really do not familiar with it, but definitely I will not do it with you, because you cannot provide any useful information, except stupid talking about "you're wrong", "go do some studying and some learning", etc...

I believe that the topic has exhausted itself. Sorry, but I don't see the reason to discuss with you about personalities. I’m not at all interested in this. This is a boring conversation.

« Last Edit: August 25, 2019, 12:29:40 pm by radiolistener »
 

Offline Zero999

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #92 on: August 25, 2019, 02:27:00 pm »
ok. I'm not familiar with AC alternators. May be that's true.
Good, it seems like you've finally realised there's a gap in your understanding. Please go back and do some research on alternators.

Quote
So, if I understand correctly, capacitive load leads AC alternator to keep rotating. And inductive load leads to slow down. Is it correct?
No, purely inductive or capacitive loads have little effect on the mechanical loading of the alternator.

If there is anyone in this thread who is confused it is you and you would do well to stop posting and go do some studying and some learning and stop wasting our collective time.

As I see, all what you can is just insulting and talking that other peoples don't know anything. Probably many people insulted you and talked that you don't know nothing, and it seems that they said truth, because it hooked you, and now you're trying to insult other in the same way for revenge.  ;) I'm really sorry you were so unlucky in life, but I cannot help you with that.

Your words is nothing for me, because it cannot be applied and do not matter. So, I don't care what is your thoughts. Is it possible to take offense at the donkey who kicked you?

May be I'm interested to discuss about AC alternators, because I really do not familiar with it, but definitely I will not do it with you, because you cannot provide any useful information, except stupid talking about "you're wrong", "go do some studying and some learning", etc...

I believe that the topic has exhausted itself. Sorry, but I don't see the reason to discuss with you about personalities. I’m not at all interested in this. This is a boring conversation.
No one is insulting you. Please don't take it personally. It's understandable that you feel everyone is ganging up on you.

In reality people are frustrated because they feel you're not listening. If you do some research, come back with more questions or admitting you were mistaken, then people will be happy to help.
 
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Online ejeffrey

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #93 on: August 26, 2019, 02:58:55 am »
No, the energy returned back will make thing easier for the generator, i.e., decrease torque and fuel consumption aside from the extra transmission losses.

Very large reactivate/reflected power is hard on linear amplifiers and rf power supplies because the reflected power is dissipated in the pass transistors instead of the load and can cause them to overheat.  But generators and switching/class D supplies don't have that problem.

It certainly isn't ideal.  There is a reason for the push for better power factor.  But reactive power is (mostly) not lost.
 

Offline gbaddeley

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #94 on: August 26, 2019, 09:02:52 am »
If the capacitors were really wasting power, it could only dissipated as heat. A component dissipating a few watts will get quite hot, unless it is heatsinked or large.
Glenn
 

Offline GerryR

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #95 on: August 26, 2019, 11:28:34 am »
In the USA residential consumers do not pay for reactive power, I can't speak for elsewhere.

Also as I mentioned earlier, if you have any inductive loads they will cancel out the the capacitive loads.



It isn't indicated on your bill as "reactive" power, but believe me, we are paying for it!

The purpose of pf correction is to put the current in phase with the voltage; pf is the cos of the angle.  That is why they have huge capacitor banks in motor-rich industrial environments.  If you have ever been inside a pf-correction cabinet, you will see that there is some loss by the amount of heat generated inside the cabinet, but not as much loss as what is being saved.




Still learning; good judgment comes from experience, which comes from bad judgment!!
 

Offline Ice-Tea

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #96 on: August 26, 2019, 11:34:49 am »
In the USA residential consumers do not pay for reactive power, I can't speak for elsewhere.

Also as I mentioned earlier, if you have any inductive loads they will cancel out the the capacitive loads.

It isn't indicated on your bill as "reactive" power, but believe me, we are paying for it!

I'm curious.. how exactly are you paying for it?
 

Offline GerryR

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #97 on: August 26, 2019, 12:31:57 pm »
I have no way of knowing "exactly," but I'm sure the power companies have a good idea of the total reactive power being used and have that factored into the rates we pay each month.
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Offline Ice-Tea

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #98 on: August 26, 2019, 12:40:13 pm »
Oh, sure, no doubt. But you can use 0 VAR or 10kVAR at your house and not pay a dime more.
 

Online Circlotron

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Re: nobody talking about switching PS wasting power on input filter caps?
« Reply #99 on: August 26, 2019, 01:15:41 pm »
I suppose we all pay from the point of view that the electricity supply companies install larger lines, transformer and switch gear than would be necessary if all loads were unity power factor. The extra cost of that larger equipment is passed on the consumer in one way or another.
 


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