Energy efficiency, Transformer?

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Homework Help Overview

The problem involves a power plant generating electricity at a specific voltage and the subsequent transmission of that electricity through a transformer and long-distance power lines. The context includes calculations related to voltage, current, resistance, and efficiency of the transmission system.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of Ohm's law (V=IR) for calculating current and question the appropriateness of this approach given the resistance of the transmission wires. There is also a focus on understanding the concept of efficiency in power transmission and how it relates to voltage drop along the lines.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some guidance has been offered regarding the need to consider voltage drop and efficiency in the context of the current flowing through the wires. There is a recognition of confusion around the definitions and implications of voltage at different points in the transmission system.

Contextual Notes

Participants note that the resistance discussed pertains only to the transmission wires and does not account for any load resistance at the receiving end. There is an emphasis on the distinction between sending and receiving voltages due to the resistance of the transmission line.

Daisy
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Homework Statement



A power plant produces energy at a voltage of Vi = 12693 V. Before being sent along long distance power lines this electricity is sent through a transformer with 166 turns in the primary coil and 6917 turns in the secondary coil. The voltage of the electricity sent through the long distance wires is 528900V.
If the wires have an efficiency of 99.30% and a resistance of 1089 Ω, what current flows through these wires?

Homework Equations



I have used V=IR. Of which I got V to be 485.67 and I mil

The Attempt at a Solution


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I got I = V/R to be 485.67 and I multiplied it by 0.993 in order to determine the current flowing through these wires. But I got it wrong. I don't seem to understand what is wrong. Did I use the correct equation? Or was my computation of efficiency incorrect?
 
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R is the resistance of the transmission wires and doesn't include any load resistance at the receiving end. That means your current calculation is not correct.

Instead, start by writing an expression for the voltage received at the far end assuming some (as yet unknown) current ##I## is flowing.

Next consider the definition of Efficiency in this context (power transmission).
 
I am really confused. What do you mean by voltage received at the far end?
 
Daisy said:
I am really confused. What do you mean by voltage received at the far end?
Power station at one end of the transmission line, some load at the far end. The transmission line has resistance so there will be a voltage drop between the sending end and the receiving end. Thus the voltage received at the far end is not the same as the voltage at the sending end.
 

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