3 Phase Transformer Amp Calculator

Three Phase Transformer Current Formula:

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

Current (I):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Three Phase Transformer Current Formula?

The three phase transformer current formula calculates the current (in amps) flowing through a three phase transformer based on its power rating in kilovolt-amps (kVA) and the system voltage. This calculation is essential for proper transformer sizing and electrical system design.

2. How Does the Calculator Work?

The calculator uses the three phase transformer current formula:

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

Where:

\( I \) — Current in amperes (amps)
\( kVA \) — Transformer power rating in kilovolt-amps
\( V \) — Line-to-line voltage in volts
\( \sqrt{3} \) — Mathematical constant approximately equal to 1.732

Explanation: The formula converts kVA to VA (by multiplying by 1000), then divides by the product of voltage and the square root of 3 to calculate the current in a balanced three-phase system.

3. Importance of Current Calculation

Details: Accurate current calculation is crucial for selecting appropriate circuit breakers, conductors, and protective devices, ensuring electrical system safety and efficiency.

4. Using the Calculator

Tips: Enter the transformer kVA rating and system voltage in volts. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why is the square root of 3 used in the formula?
A: The square root of 3 (approximately 1.732) accounts for the phase relationship in three-phase systems, converting between line-to-line voltage and phase voltage.

Q2: What's the difference between single-phase and three-phase calculations?
A: Single-phase calculations use I = kVA × 1000 / V, while three-phase calculations include the √3 factor to account for the three-phase power distribution.

Q3: When should this formula be used?
A: This formula is used for balanced three-phase systems to calculate current based on transformer kVA rating and system voltage.

Q4: Are there limitations to this calculation?
A: This calculation assumes a balanced three-phase load and does not account for power factor, transformer efficiency, or unbalanced loading conditions.

Q5: How does power factor affect the actual current?
A: For a more precise calculation that includes power factor, the formula would be I = kVA × 1000 / (V × √3 × PF), where PF is the power factor.