What should I do in this situation ? I have R_N <-Norton resistance and it's equal infinite

Thread Starter

Xenon02

Joined Feb 24, 2021
217
Hello !

I've got a question.
When I have R_N <-Norton resistance and it's equal infinite --> Rn = infinite. Then I can't change Norton into Thevenin ? I mean here J_N into E_TH ?
If I had R_N = 0 can I also change J_N into E_TH ?

Thank you !
 
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crutschow

Joined Mar 14, 2008
30,127
To change between a Norton and Thevenin equivalent circuit you also need the equivalent impedance of the rest of the circuit.
You can't convert an ideal current source into an ideal voltage source by itself.
 

MrAl

Joined Jun 17, 2014
9,191
Hello !

I've got a question.
When I have R_N <-Norton resistance and it's equal infinite --> Rn = infinite. Then I can't change Norton into Thevenin ? I mean here J_N into E_TH ?
If I had R_N = 0 can I also change J_N into E_TH ?

Thank you !
You should really post the circuit.

If you have an infinite resistance across an ideal current source the voltage is infinite.
If you have a zero resistance across an ideal voltage source the current is infinite.

Either of these may be ok in theory, but in practice there would be some limitation such as some series and/or parallel resistances for each type of source.

If you have zero resistance across a current source the voltage is zero.
If you have an infinite resistance in series with a voltage source the current is zero.
 

MrSalts

Joined Apr 2, 2020
1,845
You should really post the circuit.

If you have an infinite resistance across an ideal current source the voltage is infinite.
If you have a zero resistance across an ideal voltage source the current is infinite.

Either of these may be ok in theory, but in practice there would be some limitation such as some series and/or parallel resistances.
A fixed current though an infinite resistance is infinite power - a super hero. A god.
Now, would he have more power if the fixed current is increased?
 

MrAl

Joined Jun 17, 2014
9,191
A fixed current though an infinite resistance is infinite power - a super hero. A god.
Now, would he have more power if the fixed current is increased?
Hello,

Apparently you did not understand the difference between theory and practice. In theory you can have infinite quantities, in practice you cant, but i already indicated that in the previous post.
 

MrSalts

Joined Apr 2, 2020
1,845
Hello,

Apparently you did not understand the difference between theory and practice. In theory you can have infinite quantities, in practice you cant, but i already indicated that in the previous post.
Are you telling me you're changing your mind about infinite voltage?
 

MrAl

Joined Jun 17, 2014
9,191
Are you telling me you're changing your mind about infinite voltage?
You dont seem to understand what you read sorry.
Everything i stated before this is hard core facts. If you dont understand, you have to ask somebody or read a book.

Your example was a practical one, while my reply before had BOTH practical and theoretical parts, with the statements they went with. Two were theoretical, two were more practical.

If you want to discuss this further we should talk in PM's and not muddy up this thread. Thanks in advance for your anticipated cooperation.
 

crutschow

Joined Mar 14, 2008
30,127
So it is impossible to have Norton with Rn = 0?
Not impossible, but it would be of no practical use.
The Norton source would look like a short-circuit, with zero output voltage.
Practical equivalent sources need some finite impedance (not zero or infinite).
 

Thread Starter

Xenon02

Joined Feb 24, 2021
217
Not impossible, but it would be of no practical use.
The Norton source would look like a short-circuit, with zero output voltage.
Practical equivalent sources need some finite impedance (not zero or infinite).
Maybe you are right but if I want to have Thevenince Voltage source from Norton source with RN = 0 then RT = 0 and ET= Jn*RT and we have ET = 0. Which is not logika because for Norton source the additional resistor R will have a Voltage equal UR= Jn*R.
But for ET it implicates that resistor R have no Voltage.Sorry for my lack of vocabulary some of my sentences May Sound stupid. But I believe you can Understand something out of it :D
 

Thread Starter

Xenon02

Joined Feb 24, 2021
217
I mean I know it is not practical but in the same time it is a bit conflicting as I mentioned before if I want to change Et to Jn.

Thanks for the answer
 

MrAl

Joined Jun 17, 2014
9,191
I meant something like this :

View attachment 269780

If it's unreadable then I'll write it again.
Hi again,

Take a look...

If you have 10 amps and 0 Ohms in parallel with 6 Ohms, the Thevenin voltage is 10*0=0 and the resistance is 0*6/(0+6)=0.
If you have 6 amps and 0 Ohms in parallel with 46 Ohms, the Thevenin voltage is 6*0=0 and the resistance is 0*46/(0+46)=0.
If you have 106 amps and 0 Ohms in parallel with 14 Ohms, the Thevenin voltage is 106*0=0 and the resistance is 0*14/(0+14)=0.
If you have Ix amps and 0 Ohms in parallel with R Ohms, the Thevenin voltage is Ix*0=0 volts and the resistance is 0*R/(0+R)=0 Ohms.

So in every case the Thevenin voltage is 0v and the resistance is 0 Ohm.
If that makes you happy then you are good to go :)

There may be one exception depending on how you look at it and that is if the current goes toward infinite and the resistance goes toward zero. You may then make an argument that the voltage is exactly 1 volt. Since we cant really have infinite current though this exception really isnt that important.
 
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