1. What is Transformer Size Calculation?

Transformer size calculation determines the appropriate kilovolt-ampere (kVA) rating for a transformer based on voltage and current requirements. Proper sizing ensures efficient operation and prevents overload conditions.

2. How Does the Calculator Work?

The calculator uses the 3-phase transformer formula:

Where:

• \( Voltage \) — Line-to-line voltage in volts (V)
• \( Current \) — Line current in amperes (A)
• \( \sqrt{3} \) — Constant for 3-phase systems (approximately 1.732)
• \( 1000 \) — Conversion factor from VA to kVA

Explanation: This formula calculates the apparent power in a 3-phase electrical system, which determines the required transformer size.

3. Importance of Transformer Sizing

Details: Proper transformer sizing is crucial for system efficiency, voltage regulation, and preventing equipment damage. Undersized transformers can overheat and fail, while oversized transformers are inefficient and costly.

4. Using the Calculator

Tips: Enter voltage in volts (V) and current in amperes (A). Ensure values are positive and represent the system's operating parameters. The calculator provides the transformer size in kVA.

5. Frequently Asked Questions (FAQ)

Q1: Why is √3 used in the 3-phase formula?
A: √3 (approximately 1.732) is the mathematical constant that relates line-to-line voltage to phase voltage in balanced 3-phase systems.

Q2: What is the difference between kVA and kW?
A: kVA measures apparent power (voltage × current), while kW measures real power. The ratio between them is the power factor (cos φ).

Q3: How do I account for future load growth?
A: Add a safety margin (typically 15-25%) to the calculated kVA to accommodate future expansion and prevent frequent transformer replacements.

Q4: What about single-phase transformers?
A: For single-phase systems, use: kVA = (Voltage × Current) / 1000, without the √3 factor.

Q5: How does ambient temperature affect transformer sizing?
A: Higher ambient temperatures reduce transformer capacity. Manufacturers provide derating factors for different temperature conditions.