How Do You Solve the Supernode Equation Involving Node C?

  • Thread starter noname1
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In summary, the conversation revolves around solving a super node equation with several variables. The main issue is with node C and how to properly include the 12.5 resistor in the equation. It is eventually determined that the equation for node C is simply Vc = 150, and the error for node D is corrected. The final answers for all variables are also provided.
  • #1
noname1
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I am trying to resolve this super node but i am having trouble with the equation, more specifically node c, this is where i got so far


5 = Va/20 +(Va - Vd)/10 + (Vb - Vc)/12.5
-10 = (Vd - Va)/10 + Vd/25
-Va + Vb = 100

please explain the c node equation
 

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  • #2
Assuming the positive end of the 150 volt battery is connected to node C, then the equation is simply: Vc = 150
 
  • #3
but don't we have to include the 12.5 resistor from node b to node c?
 
  • #4
That resistor is taken care of by your first equation.

When you have a voltage source connected from ground to some node, you need a (constraint) equation that simply says that the voltage at (in this case) node C is 150 volts.

It's similar to your third equation.
 
  • #5
i am getting an error on node d can anyone tell me what i am doing wrong, its the 3rd equation on the last process
 

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  • #6
I think that equation should be:

-5Va + 7Vd = -500

For final answers, I get:

Va = 11.712
Vb = 111.712
Vc = 150
Vd = -63.063
 

1. What is a supernode equation?

A supernode equation is a method used in circuit analysis to simplify complex circuits that contain dependent and independent sources. It involves combining two or more nodes in a circuit into a single supernode, allowing for easier analysis and calculation of current and voltage values.

2. How do I determine which nodes to combine into a supernode?

To determine which nodes to combine, you must first identify any nodes that have a voltage source between them. These nodes can be combined into a supernode. Additionally, any nodes that share a common voltage source can also be combined into a supernode.

3. What is the benefit of using a supernode equation?

The main benefit of using a supernode equation is that it simplifies complex circuits, making it easier to analyze and calculate values such as current and voltage. This method also reduces the number of equations and unknown variables, making the solution process more efficient.

4. Are there any limitations to using a supernode equation?

Yes, there are some limitations to using a supernode equation. This method can only be used for circuits that have dependent and independent sources. Additionally, it cannot be used for circuits that contain voltage sources in parallel with current sources.

5. How do I solve a circuit using a supernode equation?

To solve a circuit using a supernode equation, you must first identify and combine any applicable nodes into a supernode. Then, you can use Kirchhoff's laws and Ohm's law to write equations and solve for the unknown values. Finally, you can use algebraic manipulation to solve for the remaining variables and determine the values of current and voltage in the circuit.

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