1. What is 3-Phase Motor Current?

The full load current is the current drawn by a 3-phase AC motor when operating at its rated power, voltage, and frequency with 100% load. It's crucial for proper circuit protection and conductor sizing.

2. How Does the Calculator Work?

The calculator uses the 3-phase current formula:

Where:

• \( I \) — Current in amperes (A)
• \( P \) — Power in watts (W)
• \( V \) — Line voltage in volts (V)
• \( PF \) — Power factor (0-1)
• \( eff \) — Motor efficiency (0-1)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula accounts for all electrical characteristics of a 3-phase motor to determine the current draw at full load.

3. Importance of Current Calculation

Details: Accurate current calculation is essential for selecting proper wire sizes, circuit breakers, overload protection, and motor starters to ensure safe and efficient operation.

4. Using the Calculator

Tips: Enter motor power rating in watts, line voltage in volts, typical power factor (usually 0.8-0.95), and motor efficiency (usually 0.8-0.95). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's typical power factor for motors?
A: Induction motors typically have PF of 0.85-0.9 at full load, lower at partial loads. Synchronous motors can achieve unity (1.0) PF.

Q2: How does voltage affect current?
A: Current is inversely proportional to voltage. Higher voltage systems draw less current for the same power.

Q3: What if I know horsepower instead of watts?
A: Convert HP to watts (1 HP = 746 W) before using the calculator.

Q4: Why include efficiency?
A: Motors convert some electrical energy to heat. Efficiency accounts for these losses in current calculation.

Q5: How accurate is this calculation?
A: It provides theoretical full-load current. Actual current may vary due to manufacturing tolerances, operating conditions, and power quality.