How Can I Correct Errors in My Circuit Mesh Analysis?

Click For Summary
SUMMARY

This discussion focuses on correcting errors in circuit mesh analysis involving four meshes (I1, I2, I3, and I4) and the application of Ohm's Law. The user initially attempted to calculate mesh currents using the formula I = V/Z but was advised that the voltage across impedances must consider series connections. Key issues identified include sign errors in the mesh equations and the importance of clearly indicating mesh current directions. The recommended approach is to write mesh equations symbolically before substituting numerical values.

PREREQUISITES
  • Understanding of mesh analysis in electrical circuits
  • Familiarity with complex impedance and Ohm's Law
  • Knowledge of Kirchhoff's Voltage Law (KVL)
  • Ability to manipulate complex numbers in circuit equations
NEXT STEPS
  • Review the principles of mesh analysis in electrical engineering
  • Learn about complex impedance and its application in AC circuits
  • Practice writing and solving mesh equations symbolically
  • Study the impact of sign conventions in circuit analysis
USEFUL FOR

Electrical engineering students, circuit designers, and anyone involved in analyzing AC circuits using mesh analysis techniques.

Toolkit
Messages
2
Reaction score
2

Homework Statement



TMA question Mesh analysis.PNG


Homework Equations



I've worked out the KVL's for four meshes, I1, I2,I3, and I4. Would anyone be able to error check this for me?

Also, would I be correct in thinking that I can use ohm's law by dividing V1/Z1 to find the current of the first mesh and likewise with V2/Z3?

The Attempt at a Solution


[/B]
I1 : I1(-2Ω+J5Ω) -J5Ω(I2) = 120∠0°v

I2: -J5Ω(I1) -J4Ω(I2)+J4Ω(I3)+J5Ω(I4)=0

I3: J4Ω(I2) + J8Ω (I3) = 120 ∠90°

I4: J5Ω (-I2) = J5Ω (I4) = 20∠40°

Thanks,

Toolkit

 

Attachments

  • TMA question Mesh analysis.PNG
    TMA question Mesh analysis.PNG
    20.5 KB · Views: 911
Physics news on Phys.org
Toolkit said:
Also, would I be correct in thinking that I can use ohm's law by dividing V1/Z1 to find the current of the first mesh and likewise with V2/Z3?

That would not be correct. The voltage across Z1 is not just V1. The voltage across Z4 is in series with V1 and those two voltages are then across Z1. The same reasoning applies to the voltage across Z3.

This problem requires close attention to signs of impedances and current directions. You should indicate on the schematic the mesh current directions you have assumed. A common convention is to assume mesh currents are clockwise as shown here. Node designations are also shown which will be handy when doing a nodal solution:

t659iw.jpg


Have you tried solving your equations? I think you have some sign errors. I would write the mesh equations keeping the voltages and impedances in symbolic form (that is, use V2 instead of 120 /_90, use Z1 instead of 2 ohms, Z2 instead of -j5 ohms, etc.). Once you have them written out like that, double check the signs of voltages and currents. When you're sure you have all that right, substitute numerical values for the impedances and voltages.
 

Attachments

  • t659iw.jpg
    t659iw.jpg
    10.8 KB · Views: 448

Similar threads

  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 187 ·
7
Replies
187
Views
59K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
9
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 26 ·
Replies
26
Views
3K
Replies
18
Views
2K
  • · Replies 65 ·
3
Replies
65
Views
8K