Calculating Power Loss in a High Voltage Transmission Line

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Homework Help Overview

The discussion revolves around calculating power loss in a high voltage transmission line, specifically focusing on the resistance of the wire and the current flowing through it. The subject area includes electrical engineering concepts related to power transmission and resistance.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the power loss by comparing the initial and final power values, raising a question about a potential math error. Some participants question the necessity of calculating the difference in power, suggesting a more direct approach using the formula for power loss.

Discussion Status

Participants are exploring different interpretations of the problem, with some suggesting that the teacher may be asking for the power dissipated rather than the remaining power. There is acknowledgment of a misunderstanding in the problem statement, indicating a productive direction in clarifying the requirements.

Contextual Notes

There is mention of potential confusion due to the wording of the problem in the textbook, which may have contributed to misinterpretation by the original poster.

SparkimusPrime
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A question surprisingly similar to this:

https://www.physicsforums.com/showthread.php?t=17219

I = 1000amp
V = 700,000volt
distance = 100miles
resistance of the wire = .5 ohm / mile

The resistance of my line is 50 ohms, original power is 7e5 * 1e3 = 7e8 watts. Final power, due to P = (I^2) * R, is 1e3^2 * 50 = 5e7 watts

So finding the difference:

7e8 - 5e7 = 6.5e8

The answer given by the teacher is 50 MW (50e6 watts right?). A math error I'm sure, anyone see it?

Peter
 
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I am not sure why you are computing the difference.

The power lost by the line is

P=I2R

End of story, you do not even need to know the total power transmitted.
 
Maybe your teacher wants the power dissipated by the wire, and not the power that is left?

Beat me to it. :smile:
 
Yes sorry, read the problem wrong. Seems to be a common failing with this book, using obscure english to mask the real problem.

Thanks.

Peter
 

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