1. What is a 3-Phase Motor Amp Calculator?

Definition: This calculator determines the current (in amps) drawn by a three-phase electric motor based on its power rating, operating voltage, and power factor.

Purpose: Helps electricians and engineers properly size electrical components and verify motor load requirements.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Current (amps)
• \( P_{kW} \) — Power (kilowatts)
• \( V \) — Voltage (volts)
• \( PF \) — Power factor (0 to 1)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: Converts kW to watts (×1000), then divides by the product of voltage, power factor, and √3 (for three-phase power).

3. Importance of 3-Phase Current Calculation

Details: Accurate current calculation ensures proper wire sizing, circuit breaker selection, and prevents equipment damage from overload.

4. Using the Calculator

Tips: Enter motor power in kW, line voltage (default 480V), and power factor (default 0.85). Power factor must be between 0.1 and 1.

5. Frequently Asked Questions (FAQ)

Q1: Why is √3 used in the formula?
A: The √3 accounts for the phase difference in three-phase systems, converting between line-to-line and phase quantities.

Q2: What's a typical power factor for motors?
A: Induction motors typically have 0.85 PF at full load, but this varies with motor size and load conditions.

Q3: Should I use line-to-line or line-to-neutral voltage?
A: Always use line-to-line (phase-to-phase) voltage for this calculation.

Q4: How does motor efficiency affect the calculation?
A: This formula assumes 100% efficiency. For more precision, divide the result by the motor efficiency (as a decimal).

Q5: Can I use this for single-phase motors?
A: No, use I = P×1000/(V×PF) for single-phase systems (without the √3 factor).