3 Phase Transformer Calculator

3 Phase Transformer Formula:

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

Transformer Rating (kVA):

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1. What is the 3 Phase Transformer Formula?

The 3 phase transformer formula calculates the apparent power (kVA) rating of a three-phase transformer based on line voltage and line current. This is essential for proper transformer sizing in electrical systems.

2. How Does the Calculator Work?

The calculator uses the 3 phase transformer formula:

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

Where:

\( V \) — Line voltage (volts)
\( I \) — Line current (amps)
\( \sqrt{3} \) — Constant for three-phase systems (≈1.732)
1000 — Conversion factor from VA to kVA

Explanation: The formula accounts for the phase relationship in three-phase systems, where the total power is √3 times the product of line voltage and current.

3. Importance of Transformer Rating

Details: Proper transformer sizing is critical for electrical system efficiency, safety, and reliability. Undersized transformers can overheat, while oversized ones are inefficient and costly.

4. Using the Calculator

Tips: Enter line voltage in volts and line current in amps. Both values must be positive numbers. The calculator will compute the transformer rating in kVA.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between single-phase and three-phase transformers?
A: Three-phase transformers handle three alternating currents with 120° phase difference, allowing more power delivery with less material compared to single-phase.

Q2: How does this differ from single-phase transformer calculation?
A: Single-phase uses kVA = V × I / 1000, while three-phase includes the √3 factor to account for phase relationships.

Q3: What are typical voltage ratings for three-phase transformers?
A: Common voltages include 208V, 240V, 480V, 600V (low voltage) and higher for industrial applications.

Q4: Should I add a safety factor to the calculated kVA?
A: Typically add 20-25% margin for future expansion and to prevent operation at full capacity.

Q5: How does power factor affect transformer sizing?
A: This calculator gives apparent power (kVA). For real power (kW) you need to consider power factor (PF): kW = kVA × PF.