Calculating Voltage, Current, and Power in High Voltage Electrical Systems

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The discussion focuses on calculating voltage, current, and power in a high voltage electrical system with a total resistance of 4 ohms, an rms voltage of 400kV, and an input power of 500MW. The minimum voltage that insulators must withstand is questioned, with clarification needed on the definition of rms voltage and its implications for peak voltage. The calculated rms current is debated, with one participant arriving at 1250 Amps using the power formula, while another suggests a much higher value of 100,000 Amps, indicating confusion over the calculations. The power loss in the line is also addressed, emphasizing the importance of understanding the relationship between input voltage, current, and resistance. Overall, the thread highlights the complexities of high voltage calculations and the need for careful application of electrical formulas.
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Homework Statement


Electrical energy supplied by a high voltage power has a total resistance of 4 ohms. At the input to the line the rms voltage is 400kV and the input power is 500MW

Calculate : A) the min voltage that the insulators which support the line must withstand without breakdwon

B) The value of rms current in the power line

C) the power loss in the power line

Homework Equations


P=I^2R
P=0.5IV (average power)
Peak I = 0.707 Irms


The Attempt at a Solution



Is it -400 kV? because I can't understand any other way it can be "minimum" without breakdown

B) I did P= IV and got 1250 Amps and if I use V=IR I get 100,000 Amps, since both current are ridiculously high, I doubt they are right.

C) P= I^2R?
 
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The input voltage is specified as an rms value. What does that tell you about the PEAK voltage?

The input power is the product of the input voltage and the input current, so your value of 1250 Amps looks reasonable -- keep in mind that it is a 500 mega-Watt system!
 
A) Just look at the rms definition for a sine wave, and draw on a paper the sine wave and its rms value.
B) Looks like you have to find the resistance of the load. It's a voltage source and two resistors. Then play with the formulas you wrote.

You are dealing with several megawatts, it's rather normal you get high current values.
 

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