1. What is 3 Phase Motor Current Calculator?

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

Purpose: It helps electricians, engineers, and technicians properly size electrical components and ensure safe operation of three-phase motors.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The formula converts kW to watts (×1000), then divides by the product of voltage, power factor, and the square root of 3 for three-phase systems.

3. Importance of 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 (typically 400V for industrial systems), and power factor (default 0.85). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical power factor for motors?
A: Most motors range from 0.8 to 0.9 PF when fully loaded. Smaller motors often have lower power factors.

Q2: Why use line voltage instead of phase voltage?
A: Line voltage (phase-to-phase) is the standard measurement in three-phase systems and what's typically specified on motor nameplates.

Q3: How does motor efficiency affect the calculation?
A: This formula gives the input current. For output current, you'd need to divide by the motor efficiency (η) as well.

Q4: What voltage should I use for 480V systems?
A: Simply enter 480 in the voltage field. Common three-phase voltages include 208V, 400V, 480V, and 600V.

Q5: Can I use this for single-phase motors?
A: No, single-phase motors use a different formula without the √3 factor.