What are the implications of Thevenin equivalent circuits on circuit behavior?

In summary: Thevenin equivalent will have the same time constant, effective R and L, but the R and L will be in parallel. OK, it's been a very long time since I took EE and if I ever knew that I had forgotten it. Thanks.The Norton source can be replaced by its Thevenin equivalent. A source transformation will do. To find the time constant, effective R and L need to be in series. Thevenin equivalent will have the same time constant, effective R and L, but the R and L will be in parallel.
  • #1
Mjmuk
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Circuit.png
Hiya, this is my first time posting so apologies for any errors in formatting. :oldsmile:
I am confused as to whether when Thevenising a portion of a circuit is it to simplify BUT provide the same output characteristics, meaning the workings of the Thevenin part of the circuit may behave completely differently to the original circuit?

I have an example which may explain this better (hopefully it attached, if not here's a link http://imgur.com/VGa0TI5 ) by Thevenising the left hand side initially I assumed it would make the question easier but the answers turn out to be different when concerning the resistor in particular, is this because the Inductor 'sees' the same characteristics as before but the resistor behaves differently?

Many Thanks
 
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  • #2
Mjmuk said:
Hiya, this is my first time posting so apologies for any errors in formatting. :oldsmile:
I am confused as to whether when Thevenising a portion of a circuit is it to simplify BUT provide the same output characteristics, meaning the workings of the Thevenin part of the circuit may behave completely differently to the original circuit?
If the "Thevenin equivalent" is not exactly equivalent as far as the rest of the circuit is concerned, then it is not equivalent, so not a Thevenin equivalent. How it works internally is irrelevant as long as the rest of the circuit can't tell the difference.

As far as I am aware, Thevenin equivalents are for resistive circuits, not reactive circuits.
 
  • #3
There were 3 files attached. They seemed to be identical so I have deleted two.
 
  • #4
phinds said:
As far as I am aware, Thevenin equivalents are for resistive circuits, not reactive circuits.
I believe Thevenin equivalents are also for reactive circuits.(e.g. In case of ac circuits, maximum power is transferred to the load if the load impedance is complex conjugate of the Thevenin impedance viewed from the load terminals.)
The circuit shown in the OP can be reduced to its Thevenin equivalent.
 
  • #5
cnh1995 said:
I believe Thevenin equivalents are also for reactive circuits.(e.g. In case of ac circuits, maximum power is transferred to the load if the load impedance is complex conjugate of the Thevenin impedance viewed from the load terminals.)
The circuit shown in the OP can be reduced to its Thevenin equivalent.
OK, it's been a very long time since I took EE and if I ever knew that I had forgotten it. Thanks.
 
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  • #6
The Norton source can be replaced by its Thevenin equivalent. A source transformation will do. To find the time constant, effective R and L need to be in series.
 

1. What is a Thevenin equivalent circuit?

A Thevenin equivalent circuit is a simplified representation of a complex electrical circuit. It consists of a voltage source in series with a resistance and is used to analyze the behavior of a circuit at a specific point.

2. How is the Thevenin equivalent circuit calculated?

The Thevenin equivalent circuit is calculated by finding the open-circuit voltage at the desired point in the circuit and the equivalent resistance at that point. The open-circuit voltage is the voltage across the two points when no current is flowing, and the equivalent resistance is the resistance between the two points when all independent sources are turned off.

3. What is the purpose of using a Thevenin equivalent circuit?

A Thevenin equivalent circuit is used to simplify complex circuits and make them easier to analyze. It allows us to determine the behavior of a circuit at a specific point without having to consider the entire circuit.

4. How does the Thevenin equivalent circuit relate to Ohm's Law?

The Thevenin equivalent circuit follows Ohm's Law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. The voltage and resistance values in a Thevenin equivalent circuit are calculated using Ohm's Law.

5. Can a Thevenin equivalent circuit accurately represent any complex circuit?

No, a Thevenin equivalent circuit can only represent linear circuits. Non-linear elements such as diodes, transistors, and capacitors cannot be accurately represented by a Thevenin equivalent circuit.

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