Superposition calculation for a circuit

In summary, Gniell believes that the equation went wrong when he was dealing with the numerator and that he needs to redo it.
  • #1
billyray
58
1

Homework Statement


I have tried to answer the superposition question in the included file. I have gone through the workings as the same as in my john bird electrical book. I believe I have done nothing wrong in my approach and should be getting the same answer as my thevenins answer. the current through the load is completely different though

Homework Equations


total impedance when v2 removed = j4 in series with parallel j6 and 35 + j 35 .71
v1 removed total impedance j6 in series with parallel j4 and 35 + j35.71
then volts over resistances to find I then use the currents to find load current adding i2 and i5.
i1 x j6/j6 + 35 + j 35.71 = I2
i4 x j4/j4 + 35 + j35.71 = 1 5

i5 + i2 = I load

The Attempt at a Solution


it is included in file
I have added my attemp
 

Attachments

  • superposition.pdf
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  • #2
Hi billyray,

Welcome to Physics Forums!

I've just taken a look at your work for the first part where you've suppressed the V2 source, and I find that I don't agree with your net impedance value. In particular, the imaginary component looks incorrect to me. I think things started to go off the rails when you were dealing with the numerator during the normalization of the complex fraction. This is the bit I'm referring to:

upload_2017-11-21_9-42-0.png
 

Attachments

  • upload_2017-11-21_9-42-0.png
    upload_2017-11-21_9-42-0.png
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  • #3
hi Gniell
Thank you so much for listening. I am trying very hard and small mistakes and lack of confidence is frustrating me. I have studied a lot for this and thought I could do it. I have changed the numerator as I see I did not add j4 do you think it is more wrong than this?. I have attached my correction.
 

Attachments

  • numerator.pdf
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  • #4
I then multiplied by the conjugate of the denominator that was 35- j35.71
 
  • #5
You're good until the last two lines. You can't add the j4 to the numerator at that point: it's a separate term with a different denominator.
 
  • #6
Thanks gneill
i will redo
 

Related to Superposition calculation for a circuit

1. What is superposition calculation for a circuit?

Superposition calculation is a method used to analyze the behavior of a circuit that contains multiple sources of energy, such as voltage or current. It involves breaking down the circuit into smaller, simpler circuits and calculating the individual effects of each source, before combining the results to determine the overall behavior of the circuit.

2. When is superposition calculation used?

Superposition calculation is typically used when analyzing circuits that have multiple sources of energy, such as a circuit with multiple voltage sources or a circuit with both AC and DC sources. It can also be used to calculate the effects of varying one source while keeping others constant.

3. What are the steps involved in performing a superposition calculation?

The following are the basic steps involved in performing a superposition calculation for a circuit:

  • Identify and label all sources of energy in the circuit.
  • Turn off all but one source of energy and calculate the effects of that source on the circuit.
  • Repeat the previous step for each remaining source of energy.
  • Sum the individual results to determine the overall behavior of the circuit.

4. What are the limitations of superposition calculation?

Superposition calculation assumes that all sources of energy in the circuit are independent of each other. This may not always be the case, as some sources may interact with each other and affect the overall behavior of the circuit. Additionally, superposition calculation is only accurate for linear circuits, meaning that the current or voltage response is directly proportional to the input.

5. Are there any alternatives to using superposition calculation for circuit analysis?

Yes, there are other methods of circuit analysis such as Kirchhoff's laws, Thevenin's theorem, and Norton's theorem. These methods may be more suitable for certain types of circuits or offer a quicker solution. However, superposition calculation is a useful tool for understanding the individual effects of each source in a circuit and can be used in conjunction with other methods for a more comprehensive analysis.

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