A 34.5kV, 60hz, 3ph, 3-wire primary line will supply power to 50 units of 225KVA, 34.5kV/230V, 3ph distribution transformers in a residential subdivision. What is the % voltage drop at the farthest pole approximately 2 mile long? Assume that the three conductors are arranged horizontally where Xa and Xd are 0.665 and 0.1087 ohm/mile respectively, and that the resistance of the each cable is 1.69 ohms/mile. Use one decimal place in your answer. Do not write percent symbol

Answers

Answer 1

The percentage voltage drop at the farthest pole is approximately 332.2%, if Primary line voltage ([tex]$V_p$[/tex]) = 34.5 kV and Primary line frequency ([tex]$f_p$[/tex]) = 60 Hz

To calculate the percentage voltage drop at the farthest pole, we need to consider the resistance and reactance of the transmission line as well as the load characteristics.

Primary line voltage ([tex]$V_p$[/tex]) = 34.5 kV

Primary line frequency ([tex]$f_p$[/tex]) = 60 Hz

Number of distribution transformers (N) = 50

Transformer rating (S) = 225 kVA

Primary line length (L) = 2 miles

[tex]$X_a$[/tex] = 0.665 ohm/mile (reactance per mile)

[tex]$X_d$[/tex] = 0.1087 ohm/mile (reactance per mile)

Resistance per mile (R) = 1.69 ohms/mile

First, we need to calculate the total apparent power ([tex]$S_T$[/tex]) required by the transformers:

[tex]$S_T = N \times S = 50 \times 225 \, \text{kVA} = 11250 \, \text{kVA}$[/tex]

Next, we can calculate the total line impedance (Z):

[tex]$Z = \sqrt{R^2 + (X_a + X_d)^2} = \sqrt{(1.69 \times 2)^2 + (0.665 + 0.1087)^2} = \sqrt{14.4895} \approx 3.81 \, \text{ohms/mile}$[/tex]

Now, we can calculate the total voltage drop ([tex]$V_{\text{drop}}$[/tex]) across the 2-mile line:

[tex]$V_{\text{drop}} = I \times Z \times L = \left(\frac{S_T}{\sqrt{3} \times V_p}\right) \times Z \times L = \left(\frac{11250}{\sqrt{3} \times 34.5}\right) \times 3.81 \times 2 = 114.6 \, \text{volts}$[/tex]

Finally, we can calculate the percentage voltage drop ([tex]$\%V_{\text{drop}}$[/tex]) at the farthest pole:

[tex]$\%V_{\text{drop}} = \left(\frac{V_{\text{drop}}}{V_p}\right) \times 100 = \left(\frac{114.6}{34.5}\right) \times 100 \approx 332.17\%$[/tex]

Therefore, the approximate % voltage drop at the farthest pole is 332.2%.

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Related Questions

1.Balloon Emporium sells both latex and Mylar balloons. The store owner wants a pro-gram that allows him to enter the price of a latex balloon, the price of a Mylar balloon, the number of latex balloons purchased, the number of Mylar balloons purchased, and the sales tax rate. The program should calculate and display the total cost of the purchase

Answers

an example code that implements this calculation:

price_latex = float(input("Enter the price of a latex balloon: "))

price_mylar = float(input("Enter the price of a Mylar balloon: "))

num_latex = int(input("Enter the number of latex balloons purchased: "))

num_mylar = int(input("Enter the number of Mylar balloons purchased: "))

sales_tax_rate = float(input("Enter the sales tax rate (in decimal form): "))

total_cost = (price_latex * num_latex) + (price_mylar * num_mylar)

total_cost_with_tax = total_cost + (total_cost * sales_tax_rate)

print("Total cost of the purchase (including tax):", total_cost_with_tax)

The result is displayed to the user as the total cost of the purchase, including tax.

To calculate the total cost of the purchase, you can use the following formula:

Total Cost = (Price of Latex Balloon * Number of Latex Balloons) + (Price of Mylar Balloon * Number of Mylar Balloons) + (Sales Tax * Total Cost)

Here's an example code that implements this calculation: