Maximum power transfer

[topgone]

120108-2030 EST

topgone:

Your value is nothing close to maximum power transfer.

Then, we are talking about two, very different animals! You see, with too little an information, one can only guess. How about a circuit diagram? My borrowed crystal got broken, you know?

 

[rattus]

I know how but:

I know how but:

Well, it involves calculus, and I am too old and sleepy to bother my brain with it tonight. Besides, gar wants someone else to come up with the answer.

 

[T.M.Haja Sahib]

120108-1021 EST

Speedskater:

In your post numbered #2 how do you prove that statement?

Suppose I change the source to a 100 V RMS 60 Hz sine wave with an internal impedance of 5 ohms resistance in series with a 10 H inductor, then what load results in maximum power transfer to the load?

.

gar

If you do not mind,let me try to answer.

For your first question,it can be proved by taking into consideration that the circuit becomes a lossy resonant circuit.

For your second question,the load should consist of 5 ohms resistance in series with a
10 F capacitor.

 

[steve66]

gar

If you do not mind,let me try to answer.

For your first question,it can be proved by taking into consideration that the circuit becomes a lossy resonant circuit.

For your second question,the load should consist of 5 ohms resistance in series with a
10 F capacitor.

I think you are on the right track for what Gar is looking for, but you need to think about the size of the capacitor a little more.

Steve

 

[gar]

120109-0927 EST

topgone:

I specified a source of a sine wave voltage of an RMS amplitude, a frequency, and a specific internal impedance. The question was what is the load for maximum power transfer to the load. No restriction was placed on the load because the very broad word load was used. Now it is up to you to figure out what that load is to achieve the desired goal. Implicit in the problem is that the load has no internal power generation source, and that the load consists of linear components.

Having nothing to do with this question tell me what is the maximum phase shift of an RC network?

.

 

[Speedskater]

How do I prove it? What about having the other 67,000 forum members prove it?

In your advanced question, is the load resistive?

Can we prove it by example or maybe by calculus?

 

[Besoeker]

For your first question,it can be proved by taking into consideration that the circuit becomes a lossy resonant circuit.

If you mean the question posed in post #1, what components are there mentioned that could result in any sort of resonance?[/quote]

For your second question,the load should consist of 5 ohms resistance in series with a
10 F capacitor.

As Steve66 has hinted at, you need to consider the values of X_L and X_C.

 

[T.M.Haja Sahib]

I think you are on the right track for what Gar is looking for, but you need to think about the size of the capacitor a little more.
Steve

It is of enormous size.......

The real application of maximum power transfer is in communication circuits and not in power circuits...........

 

[T.M.Haja Sahib]

If you mean the question posed in post #1, what components are there mentioned that could result in any sort of resonance?

As Steve66 has hinted at, you need to consider the values of X_L and X_C.[/QUOTE]

I do not want to be engaged in another trolling.........:lol:

 

[Besoeker]

As Steve66 has hinted at, you need to consider the values of X_L and X_C.

I do not want to be engaged in another trolling.........:lol:[/QUOTE]
Then just deal with the point of the thread.

 

[T.M.Haja Sahib]

I do not want to be engaged in another trolling.........:lol:

Then just deal with the point of the thread.[/QUOTE]

Please see post # 28.This thread appears to be irrelevant here.

 

[gar]

120109-1026 EST

Speedskater:

If you do not have a background in calculus, then in the DC question trial and error is probably your method. Once you started to see the results you might deduce the exact result.

The AC circuit requires more general background to deduce what might be the answer.

The word load is general, and I did go on to limit it to being linear and have no energy source. Thus, it is not limited to being resistive.

Do you have any calculus background to know that you can differentiate an equation and use the zero points to find the maximum and minimum points?

What is your definition of impedance and its relationship to your answer in post #2? Was your answer simply something you were told or had you ever done any calculations or thinking about the problem to try to determine a maximum value?

Is the impedance of a series LR circuit equal to the impedance of a series RC circuit where both provide the same apparent opposition to current flow from the same source?

.

 

[Besoeker]

Please see post # 28.This thread appears to be irrelevant here.

Gar asked a couple of theoretical questions.
Shall we just stick to those?

 

[iwire]

I do not want to be engaged in another trolling.........:lol:

Then just deal with the point of the thread.

That is excellent advice that should be followed.

 

[gar]

120109-1115 EST

I expected that many reading this thread would know the answers to the questions of the two separate paragraphs of my post #1. It was not intended that those that knew the answer would answer, but rather that it would challenge others to think about the questions.

Has the discussion helped anyone? I do not know. But it has caused at least a little discussion.

Steve66 is the only one so far to have even made any mention that relates to my original second paragraph.

T. J. not every electrician needs to know the answers to the questions in this thread to perform their daily work. Does the knowledge help them? Maybe. A broad basic understanding of things you work with is probably useful. More specifically to maximum power transfer --- it is a very important concept relative to photo-voltaic energy sources. It is also very important to understanding what Edison did and how this resulted in the evolution of the electric power industry.

.

 

[Besoeker]

It is of enormous size.......

Review your calculations.
The size if the capacitor just might surprise you.

 

[K8MHZ]

Yes, but can you explain how it is calculated?
I think that's what Gar was getting at.

Since the discussion has moved to AC impedance....

From Wiki:

In electrical engineering, the maximum power transfer theorem states that, to obtain maximum external power from a source with a finite internal resistance, the resistance of the load must be equal to the resistance of the source as viewed from the output terminals. Moritz von Jacobi published the maximum power (transfer) theorem around 1840, which is also referred to as "Jacobi's law".[1]

The theorem can be extended to AC circuits that include reactance, and states that maximum power transfer occurs when the load impedance is equal to the complex conjugate of the source impedance.

This is stuff I had to study for my Extra class amateur radio exam as the above knowledge is essential for designing radio antennas. I never thought I would see it discussed here. Kudos.

We (amateurs) don't really need to know the math any more, as the instruments we use will show us if we have max power transfer or not and 'do the math' internally, or just assume a 50 ohm source impedance and compare the antenna impedance (which includes radiation resistance), or we just TMS, 'tune for maximum smoke', using a wattmeter to see the power peak as reactance is manipulated with 'antenna tuners'.

Here is an early 'calculator', if you will, to help people figure out impedance effects, etc., without having to do the math.

http://en.wikipedia.org/wiki/Smith_chart

To be honest, I think our extra class study books covered complex conjugates and how to express them and why they are a consideration much better than Wiki.

I learned them to pass the test and have never had to use them as SWR and antenna analyzers are cheap and ubiquitous.

Here is the way complex impedance is figured: Z=R+jX with j being the square root of -1.

Once the impedances are correctly figured, the rule that says max power will be transferred to the load if both load and source impedances are equal applies.

 

[K8MHZ]

Big inductor......

I got to see a 14H in a power plant. It was the size of a camping trailer.

 

[K8MHZ]

Then, we are talking about two, very different animals! You see, with too little an information, one can only guess. How about a circuit diagram? My borrowed crystal got broken, you know?

There is enough info, even when he made it into an AC circuit.

All I need is algebra the way we were taught.

 

[K8MHZ]

It is also very important to understanding what Edison did and how this resulted in the evolution of the electric power industry.

I understand much of what he did and I loathe and despise him and his pal Marconi.