What is the maximum standard trip setting for a 750kVA transformer with 4.6% impedance?

What is the maximum standard trip setting for a 750kVA transformer with 4.6% impedance?

• A. 1200A
• B. 2500A
• C. 4800A
• D. 6000A

Answer: (B)

To determine the maximum standard trip setting for a transformer, you can use the transformer’s kVA rating and its percent impedance. The formula for calculating the full-load current (IL) for a transformer is: \[ I_L = \frac{kVA \times 1000}{\sqrt{3} \times V} \] However, in this case, we focus directly on the maximum trip setting based on the information provided. For a 750 kVA transformer with an impedance of 4.6%, the maximum trip setting can be calculated as follows: 1. **Calculate the full-load current** for the transformer. Assuming a standard distribution voltage of 480V, the full-load current can be found with: \[ I_L = \frac{750 \times 1000}{\sqrt{3} \times 480} \approx 901.1A \] 2. **Adjust for the impedance**. The maximum trip setting is influenced by the impedance, typically being set higher than the full-load current to accommodate for inrush conditions. Given the 4.6% impedance, the adjustment factor corresponds to: \[ \text{Maximum Trip Setting} = \frac{I_L}{\text{percentage impedance}} \]

To determine the maximum standard trip setting for a transformer, you can use the transformer’s kVA rating and its percent impedance. The formula for calculating the full-load current (IL) for a transformer is:

[ I_L = \frac{kVA \times 1000}{\sqrt{3} \times V} ]

However, in this case, we focus directly on the maximum trip setting based on the information provided. For a 750 kVA transformer with an impedance of 4.6%, the maximum trip setting can be calculated as follows:

1. Calculate the full-load current for the transformer. Assuming a standard distribution voltage of 480V, the full-load current can be found with:

[ I_L = \frac{750 \times 1000}{\sqrt{3} \times 480} \approx 901.1A ]

2. Adjust for the impedance. The maximum trip setting is influenced by the impedance, typically being set higher than the full-load current to accommodate for inrush conditions. Given the 4.6% impedance, the adjustment factor corresponds to:

[ \text{Maximum Trip Setting} = \frac{I_L}{\text{percentage impedance}} ]