1. What is 3-Phase Motor Current Calculator?

Definition: This calculator estimates the full load current of a 3-phase AC motor based on its power rating, supply voltage, and power factor.

Purpose: It helps electrical engineers and technicians determine the current draw for proper wire sizing, circuit protection, and motor performance analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Full load current (amps)
• \( P_{kW} \) — Motor power rating (kilowatts)
• \( V \) — Line voltage (volts)
• \( PF \) — Power factor (0 to 1)

Explanation: The formula converts kW to watts (×1000), then divides by the product of voltage, power factor, and √3 (1.732) for 3-phase systems.

3. Importance of Current Calculation

Details: Accurate current calculation ensures proper selection of cables, overload protection devices, and prevents motor overheating or inefficient operation.

4. Using the Calculator

Tips: Enter motor power in kW, supply voltage (typically 400V for industrial), and power factor (default 0.85). All values must be > 0, with PF ≤ 1.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical power factor for motors?
A: Induction motors typically have 0.85 PF at full load, ranging from 0.8-0.9 for efficient motors.

Q2: Why √3 in the formula?
A: √3 (≈1.732) accounts for the phase difference in 3-phase systems when converting between line and phase values.

Q3: What voltage should I use?
A: Common voltages are 208V, 230V, 400V, 460V, or 575V - check motor nameplate for exact value.

Q4: Does this work for single-phase motors?
A: No, use I = P/(V×PF) for single-phase (without the √3 factor).

Q5: Should I add safety margin?
A: Yes, size conductors and protection for 125% of full load current per electrical codes.