1. What is a Transformer Sizing Calculator?

Definition: This calculator determines the required transformer size in volt-amperes (VA) based on voltage and current requirements.

Purpose: It helps electrical engineers, technicians, and DIYers select the properly sized transformer for their applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( VA \) — Transformer size in volt-amperes
• \( V \) — Voltage in volts
• \( I \) — Current in amperes

Explanation: The voltage and current are multiplied to determine the apparent power requirement for the transformer.

3. Importance of Proper Transformer Sizing

Details: Correct transformer sizing ensures efficient power transfer, prevents overheating, and maintains system reliability.

4. Using the Calculator

Tips: Enter the voltage in volts and current in amperes. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between VA and watts?
A: VA measures apparent power (voltage × current), while watts measure real power. For resistive loads they're equal, but differ for reactive loads.

Q2: Should I add a safety margin?
A: Yes, it's common practice to select a transformer 20-30% larger than the calculated VA to account for future loads and inefficiencies.

Q3: How do I account for three-phase systems?
A: For three-phase, multiply the result by √3 (approximately 1.732) to get the total VA requirement.

Q4: What if I only know the wattage?
A: If you know the power factor (PF), divide watts by PF to get VA. For unknown PF, assume 0.8-0.9 for typical loads.

Q5: Why is transformer sizing important?
A: Undersized transformers overheat and fail prematurely, while oversized ones are inefficient and costly.