1. What is 3-Phase Motor Full Load Current?

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

2. How Does the Calculator Work?

The calculator uses the 3-phase power formula:

Where:

• \( I \) — Full load current (amps)
• \( P \) — Motor power rating (watts)
• \( V \) — Line voltage (volts)
• \( PF \) — Power factor (typically 0.8-0.95)
• \( \eta \) — Motor efficiency (typically 0.85-0.95)

Explanation: The formula accounts for the three-phase power relationship, including the √3 factor for line-to-line voltage conversion.

3. Importance of FLC Calculation

Details: Knowing the full load current is essential for selecting proper wire sizes, circuit breakers, overload protection devices, and motor starters to ensure safe and efficient operation.

4. Using the Calculator

Tips: Enter motor power in watts, line voltage in volts, power factor (typically 0.85), and efficiency (typically 0.90). All values must be positive numbers within their valid ranges.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between FLC and LRA?
A: FLC is the current at full load operation, while LRA (Locked Rotor Amps) is the initial current surge during startup, typically 5-7 times higher than FLC.

Q2: How does voltage affect FLC?
A: FLC is inversely proportional to voltage. A 10% voltage drop results in approximately 10% higher current draw.

Q3: What are typical power factors for motors?
A: Induction motors typically have 0.85-0.90 PF at full load, dropping to 0.2-0.3 at no load. Higher efficiency motors may have better PF.

Q4: Why include efficiency in the calculation?
A: Efficiency accounts for power losses in the motor. A 90% efficient motor draws more current than a 95% efficient one for the same output power.

Q5: Can I use this for single-phase motors?
A: No, single-phase motors use a different formula: I = P / (V × PF × η).