Electrical circuit Source transformation Question

[Hesch]

So without any 'clever' use of a trick like some sort of symmetry there is not conventional way to replace current sources with voltage sources,

In #6 I wrote: You cannot convert a current source into a voltage source, but you can convert a Norton equivalent into a Thevenin equivalent.

I've read the whole thread:

In #1 the figure shows types of blocks in series: Type 1 - 2 - 3 - 4 then 1 - 3 ? That's not infinite repeated blocks. How to continue?

You admit that, but then suddenly in #5 the circuit becomes a loop.

The discussion continues with Thevenin/Norton equivalents, but since the circuit now has become a (finite) loop, KVL or KCL will be a more simple solution. Now the dicussion concerns whether KCL or KVL is to be used.

The thread is a mess. You must clearify what is meant.

If you want the circuit in #1 to be of infinite lenght, you must use Thevenin/Norton equivalents in series, then make a mathematical series of voltages, currents, whatever.

 

[tim9000]

In #6 I wrote: You cannot convert a current source into a voltage source, but you can convert a Norton equivalent into a Thevenin equivalent.

I've read the whole thread:

In #1 the figure shows types of blocks in series: Type 1 - 2 - 3 - 4 then 1 - 3 ? That's not infinite repeated blocks. How to continue?

You admit that, but then suddenly in #5 the circuit becomes a loop.

The discussion continues with Thevenin/Norton equivalents, but since the circuit now has become a (finite) loop, KVL or KCL will be a more simple solution. Now the dicussion concerns whether KCL or KVL is to be used.

The thread is a mess. You must clearify what is meant.

If you want the circuit in #1 to be of infinite lenght, you must use Thevenin/Norton equivalents in series, then make a mathematical series of voltages, currents, whatever.

In my last post (#30) I suppose I meant like 'having the source like that with those parallel resistors isn't a norton/thevenin equivalent?'

I sort of was concidering infinite length, but then when that was difficult I realized that a finite length network (in post #5) would be better. Sorry for the lack of clarity.
But I thought the electrician showed that even if we use KCL or KVL for the finite series, the solution (unless numerical) is huge...unusable. So I can't figure out how to redraw it with the sources switched.Thanks

 

[Hesch]

if we use KCL or KVL for the finite series, the solution (unless numerical) is huge...unusable.

Of course you must solve the equations numerically. Manually you will solve the equations within a day, included 11 calculation errors. In #29 the Electrician has shown you a setup as for the coefficients ( I have not checked it ). You will have to enter about 40 coefficients different from 0. Write them in a file and let a program read them from the file. In this way a forgotten minus sign is easy to correct/edit.

The program/computer will solve the equations within 5 seconds with no errors. This is not unusable

 

[tim9000]

Of course you must solve the equations numerically. Manually you will solve the equations within a day, included 11 calculation errors. In #29 the Electrician has shown you a setup as for the coefficients ( I have not checked it ). You will have to enter about 40 coefficients different from 0. Write them in a file and let a program read them from the file. In this way a forgotten minus sign is easy to correct/edit.

The program/computer will solve the equations within 5 seconds with no errors. This is not unusable

Yes I see, oh well.
What's the theoretical version of a solution, the word for it, like the opposite of a 'numerical' solution, like if I was able to find a solution that was the equivilant without it being set numbers?

Also one other question, I have is, I've seen an ideal inductor modeled as a resistor in series with a leakage inductance, in series with the ideal inductor. Couldn't I model this as the resistor in series with the ideal and leakage inductors in parallel with each other?

Thanks

 

[Hesch]

What's the theoretical version of a solution, the word for it, like the opposite of a 'numerical' solution, like if I was able to find a solution that was the equivilant without it being set numbers?

Well, you are the one to know, it's your language .
Even in my language (danish), I hate these "words". The important matter is to know, what I'm doing rather than to know the word.
The opposite of a numerical solution could be an algebraic solution, but "building" equations and solve them numerically are somehow mixed disciplines.

I've seen an ideal inductor modeled as a resistor in series with a leakage inductance, in series with the ideal inductor. Couldn't I model this as the resistor in series with the ideal and leakage inductors in parallel with each other?

You should start a new thread here.

As for a known voltage/current supplied ( 60Hz, sinusoidal ): Yes. Maybe you could find the impedance = R + sL = 10Ω + j100Ω
But say you lower the frequency to 0Hz, then the impedance in the series connection will be R + sL = 10Ω + j0Ω = 10Ω.
Now say you by 60Hz have found an equivalent in parallel. Then by lowering the frequency to 0Hz, the impedance will be R || j0Ω = 0Ω.
So generally you cannot convert a model in series to a model in parallel when inductors/capacitors are included in the models.

 

[The Electrician]

Yes I see, oh well.
What's the theoretical version of a solution, the word for it, like the opposite of a 'numerical' solution, like if I was able to find a solution that was the equivilant without it being set numbers?
Thanks

It would be called a "symbolic" solution, such as the one in post #22.

 

[William White]

Analytic solution

 

[tim9000]

It would be called a "symbolic" solution, such as the one in post #22.

Analytic solution

Ah yes, Analytic was the word I was looking for, was on the tip of my tongue.

 

[tim9000]

Well, you are the one to know, it's your language .
Even in my language (danish), I hate these "words". The important matter is to know, what I'm doing rather than to know the word.
The opposite of a numerical solution could be an algebraic solution, but "building" equations and solve them numerically are somehow mixed disciplines.

You should start a new thread here.

As for a known voltage/current supplied ( 60Hz, sinusoidal ): Yes. Maybe you could find the impedance = R + sL = 10Ω + j100Ω
But say you lower the frequency to 0Hz, then the impedance in the series connection will be R + sL = 10Ω + j0Ω = 10Ω.
Now say you by 60Hz have found an equivalent in parallel. Then by lowering the frequency to 0Hz, the impedance will be R || j0Ω = 0Ω.
So generally you cannot convert a model in series to a model in parallel when inductors/capacitors are included in the models.

Ah-ha, yeah 'analystic' was the word.

Yeah that's not what I meant by what was in parallel, I took your advice and started it as a new thread:
https://www.physicsforums.com/threads/modeling-an-inductor.825613/