Power transmission lines often use a form of electric current called alternating current, but in many regions, such as the Province of Quebec, high-voltage direct-current lines are used instead. Direct current is the kind of electric current you are studying in this chapter. A certain direct-current power transmission line has a resistance of 0.255 Ω/km. 812 kV of potential drives the current from the generating station to a city located 125 km from the plant. What is the power loss due to resistance in the line?

User Icon for Henry Henry answered
12 years ago

Rt = 0.255 Ohms/km * 125km = 31.875 Ohms. = Total rewsistance.

Pl = I^2 * Rt = I^2 * 31.875 = Pwer lost.

The power loss is proportional to the square of the current. Therefore, if we don't know how much current is flowing; we can't calculate the power loss.

User Icon for Explain Bot Explain Bot answered
11 months ago

To calculate the power loss due to resistance in the line, we can use the formula:

Power Loss = (Resistance per unit length) * (Length of the transmission line) * (Current)^2

Given data:
Resistance per unit length = 0.255 Ω/km
Length of the transmission line = 125 km
Potential difference (V) = 812 kV = 812,000 V

First, we need to calculate the current flowing through the transmission line using Ohm's law:

Current (I) = Voltage (V) / Resistance

Converting the voltage to volts (V):
Voltage (V) = 812,000 V

Converting the resistance to ohms (Ω):
Resistance (R) = 0.255 Ω/km * 125 km = 31.875 Ω

Current (I) = 812,000 V / 31.875 Ω = 25,440 A

Now, we can calculate the power loss:

Power Loss = (Resistance per unit length) * (Length of the transmission line) * (Current)^2
= 0.255 Ω/km * 125 km * (25,440 A)^2

Note: The power loss is usually given in watts (W). In this case, the unit will be (Ω/km * km * A^2), which simplifies to (Ω * A^2).

Calculating:
Power Loss = 0.255 Ω/km * 125 km * (25,440 A)^2

Therefore, the power loss due to resistance in the line is equal to the result obtained from the calculation above.