Voltage Drop Calculation for #4 Cu Cable in Power Distribution System

How can we determine the maximum allowable distance for a #4 Cu cable without exceeding a specific voltage drop?

What is the maximum distance the cable can be run without exceeding a voltage drop of:
i. 2%
ii. 3%
iii. If the distance were limited to 3 miles, what would be the maximum % voltage drop?

Voltage Drop Calculation for #4 Cu Cable

To determine the maximum allowable distance for a #4 Cu cable without exceeding a specific voltage drop, we need to consider the cable's resistance, the current flowing through it, and the allowable voltage drop percentage.

When dealing with power distribution systems, it is crucial to ensure that the voltage drop along the transmission lines is within acceptable limits. This is especially important when using cables like #4 Cu in the system. Let's break down the calculation for determining the maximum allowable distance for a #4 Cu cable:

2% Voltage Drop:

In the case of a 2% voltage drop, the maximum allowable voltage drop is 2% of the source voltage, which is 6500 V * 0.02 = 130 V. By applying Ohm's Law, we can calculate the maximum allowable distance:

L = (Vd * A) / (ρ * I)

L = (130 * 21.15 * 10^-6) / (1.724 * 10^-8 * 26)

After calculations, we find that the maximum distance would be approximately 7,438 meters or 7.44 kilometers.

3% Voltage Drop:

For a 3% voltage drop, the maximum allowable voltage drop is 3% of the source voltage, which equals 195 V. Using the same formula as above, we get:

L = (195 * 21.15 * 10^-6) / (1.724 * 10^-8 * 26)

The calculated maximum distance would be approximately 4,958 meters or 4.96 kilometers.

Maximum % Voltage Drop for 3 Miles:

If the distance were limited to 3 miles (approximately 4828.03 meters), we can calculate the maximum allowable voltage drop percentage:

Vd = (I * R * 100) / (V * L)

Vd = (26 * (1.724 * 10^-8 * 4828.03)) / (6500 * 21.15 * 10^-6)

By performing the calculations, we find that the maximum allowable voltage drop would be approximately 0.798% or 0.8% voltage drop when the distance is limited to 3 miles.

Therefore, careful consideration of voltage drop calculations is essential in ensuring the efficient and reliable operation of power distribution systems.