What is the short circuit capacity of a 72 KVA transformer with a 240V secondary and 3% impedance?

What is the short circuit capacity of a 72 KVA transformer with a 240V secondary and 3% impedance?

• A. 5,000 A
• B. 8,000 A
• C. 10,000 A
• D. 12,000 A

Answer: (C)

To determine the short circuit capacity of a transformer, you first need to understand the concept of impedance and how it relates to the full-load current of the transformer. The short circuit current can be calculated using the formula: \[ I_{sc} = \frac{V_{secondary}}{Z} \] where \(I_{sc}\) is the short circuit current, \(V_{secondary}\) is the secondary voltage of the transformer, and \(Z\) is the impedance expressed as a decimal. 1. **Convert the impedance percentage to decimal form**: The impedance is given as 3%, which would be used in the calculation as 0.03. 2. **Calculate the full-load current**: First, we need to calculate the full-load current of the transformer. The formula for full-load current (I_load) in Amperes is given by: \[ I_{load} = \frac{KVA \times 1000}{V} \] In this case, \(KVA = 72\) and \(V = 240\), \[ I_{load} = \frac{72 \times 1000}{240} = 300 \text{ A}

To determine the short circuit capacity of a transformer, you first need to understand the concept of impedance and how it relates to the full-load current of the transformer.

The short circuit current can be calculated using the formula:

[

I_{sc} = \frac{V_{secondary}}{Z}

]

where (I_{sc}) is the short circuit current, (V_{secondary}) is the secondary voltage of the transformer, and (Z) is the impedance expressed as a decimal.

1. Convert the impedance percentage to decimal form: The impedance is given as 3%, which would be used in the calculation as 0.03.

2. Calculate the full-load current:

First, we need to calculate the full-load current of the transformer. The formula for full-load current (I_load) in Amperes is given by:

[

I_{load} = \frac{KVA \times 1000}{V}

]

In this case, (KVA = 72) and (V = 240),

[

I_{load} = \frac{72 \times 1000}{240} = 300 \text{ A}