1. What is a Transformer Size Calculator?

Definition: This calculator determines the appropriate transformer size in kVA based on the required power, voltage, and power factor.

Purpose: It helps electrical engineers and technicians select the right transformer for power distribution systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Size \) — Transformer size (kVA)
• \( P \) — Power requirement (kW)
• \( V \) — Voltage (volts)
• \( PF \) — Power factor (decimal between 0 and 1)

Explanation: The power requirement is divided by the product of voltage and power factor to determine the apparent power in kVA.

3. Importance of Proper Transformer Sizing

Details: Correct transformer sizing ensures efficient power distribution, prevents overload conditions, and maintains system reliability.

4. Using the Calculator

Tips: Enter the power in kW, voltage (default 480V), and power factor (default 0.8). Power factor must be between 0.01 and 1.

5. Frequently Asked Questions (FAQ)

Q1: Why is power factor important in transformer sizing?
A: Power factor represents the ratio of real power to apparent power. Lower power factors require larger transformers for the same real power.

Q2: What's a typical power factor value?
A: Industrial loads typically have power factors between 0.8 and 0.95. The default value of 0.8 is conservative for most applications.

Q3: Should I add a safety margin to the calculated size?
A: Yes, it's common practice to add 10-25% to the calculated size to account for future load growth and transient conditions.

Q4: How does voltage affect transformer size?
A: Higher voltages result in smaller kVA requirements for the same power, as current (and thus apparent power) decreases with increasing voltage.

Q5: Can this calculator be used for three-phase systems?
A: This calculator provides basic sizing. For three-phase systems, you would need to include the √3 (1.732) factor in the calculation.