Calculating Power Loss in a High Voltage Transmission Line

  • Thread starter Thread starter SparkimusPrime
  • Start date Start date
AI Thread Summary
The discussion revolves around calculating power loss in a high voltage transmission line with given parameters: current of 1000 amps, voltage of 700,000 volts, and a resistance of 0.5 ohms per mile over 100 miles. The initial power is calculated as 700 million watts, while the power loss due to resistance is found to be 50 million watts using the formula P = I^2 * R. A misunderstanding arises regarding whether to calculate the total power transmitted or just the power dissipated by the wire. Participants clarify that the focus should be on the power lost, which is 50 million watts, not the difference from the total power. The conversation highlights the importance of accurately interpreting the problem statement.
SparkimusPrime
Messages
35
Reaction score
0
A question surprisingly similar to this:

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

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

The resistence 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
 
Physics news on Phys.org
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
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Long distance electrical transmission efficiency
Replies
2
Views
2K
To reduce cost and weight, power transmission lines are made
Replies
6
Views
1K
Power Line Losses: Trivial Problem, Confusing Answer
Replies
9
Views
2K
Why is power loss = I^2R instead of P=VI or P=I^2R?
Replies
14
Views
3K
Power loss in the transmission system with a transformer
Replies
4
Views
2K
Current Flowing through High Voltage AC Transmission Lines
Replies
8
Views
2K
Power loss in transmission lines
Replies
20
Views
11K
Finding the Power Loss Through a Transmission Line
Replies
4
Views
3K
P = VI = (281V)(3.75A) = 1054 W
Replies
6
Views
7K
How can stepping up and down the voltage save energy in power transmission?
Replies
2
Views
1K

Hot Threads

Recent Insights

Back
Top