Transformer Current Calculation 3 Phase

3-Phase Current Formula:

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

Current (amps):

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1. What is 3-Phase Transformer Current Calculation?

Definition: This calculator determines the current (in amps) flowing through a three-phase transformer based on its kVA rating and operating voltage.

Purpose: Essential for electrical engineers and technicians to properly size conductors, protection devices, and ensure safe transformer operation.

2. How Does the Calculator Work?

The calculator uses the formula:

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

Where:

\( I \) — Current (amps)
\( kVA \) — Transformer apparent power (kilovolt-amperes)
\( V \) — Line-to-line voltage (volts)
\( \sqrt{3} \) — Constant for three-phase systems (≈1.732)

Explanation: The formula converts kVA to VA (×1000), then divides by the three-phase voltage (line voltage × √3) to get current.

3. Importance of Current Calculation

Details: Accurate current calculation ensures proper conductor sizing, circuit breaker selection, and prevents transformer overload conditions.

4. Using the Calculator

Tips: Enter the transformer's kVA rating and operating voltage (line-to-line). Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Is this formula for line or phase current?
A: This calculates line current in a three-phase system.

Q2: What voltage should I use?
A: Use the line-to-line (phase-to-phase) voltage, not phase-to-neutral.

Q3: Does this account for power factor?
A: No, this calculates apparent current. For real current, divide by power factor.

Q4: Can I use this for single-phase transformers?
A: No, use I = (kVA × 1000) / V for single-phase systems.

Q5: What's typical current for a 100kVA, 480V transformer?
A: About 120.3 amps (100×1000)/(480×1.732).