1. What is Transformer Sizing Calculation?

Transformer sizing calculation determines the appropriate kVA rating for a transformer based on the electrical load current and voltage. Proper sizing ensures efficient operation and prevents overload conditions.

2. How Does the Calculator Work?

The calculator uses the transformer sizing formula:

Where:

• \( I \) — Current in amperes (A)
• \( V \) — Voltage in volts (V)
• \( 1.732 \) — Square root of 3 (for three-phase systems)

Explanation: This formula calculates the apparent power (kVA) required for a three-phase transformer based on the load current and system voltage.

3. Importance of Proper Transformer Sizing

Details: Correct transformer sizing is essential for energy efficiency, voltage regulation, and preventing overheating. Oversized transformers waste energy, while undersized ones can overheat and fail prematurely.

4. Using the Calculator

Tips: Enter current in amperes and voltage in volts. For single-phase systems, use appropriate conversion factors. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Is this formula for single-phase or three-phase systems?
A: This formula is specifically for three-phase systems. For single-phase systems, use: kVA = (I × V) / 1000

Q2: What safety factor should be added to the calculated kVA?
A: Typically, a 20-25% safety margin is added to account for future load growth and transient conditions.

Q3: How does power factor affect transformer sizing?
A: This formula calculates apparent power (kVA). For real power (kW) considerations, divide by the power factor: kW = kVA × PF

Q4: What are typical transformer size standards?
A: Common standard sizes include: 15, 30, 45, 75, 112.5, 150, 225, 300, 500, 750, 1000 kVA and larger.

Q5: When should derating factors be applied?
A: Derating may be needed for high ambient temperatures, high altitudes, or harmonic-rich loads that cause additional heating.