1. What is Full Load Amps (FLA)?

Full Load Amps (FLA) is the current a motor draws while operating at its rated load, voltage, and frequency. It's a crucial parameter for selecting proper wire sizes, circuit breakers, and overload protection devices in electrical systems.

2. How Does the Calculator Work?

The calculator uses the three-phase motor current formula:

Where:

• \( I \) — Full load current (amps)
• \( P \) — Motor power rating (watts)
• \( V \) — Line voltage (volts, typically 400V in UK)
• \( PF \) — Power factor (0-1, typically 0.85 for motors)
• \( \eta \) — Motor efficiency (0-1, typically 0.8-0.95)

Explanation: The formula accounts for the three-phase power relationship and motor performance characteristics.

3. Importance of FLA Calculation

Details: Accurate FLA calculation is essential for proper electrical system design, preventing overheating, ensuring safety, and maintaining equipment longevity.

4. Using the Calculator

Tips: Enter motor power in watts, voltage in volts (400V is standard UK three-phase), typical power factor between 0.8-0.9, and motor efficiency (usually 0.85-0.95 for modern motors).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between FLA and LRA?
A: FLA is full load current during normal operation, while LRA (Locked Rotor Amps) is the current drawn during startup (typically 5-7 times FLA).

Q2: What voltage should I use for UK calculations?
A: For three-phase motors in the UK, use 400V (standard UK three-phase voltage).

Q3: How do I find my motor's power factor?
A: Check motor nameplate or manufacturer specs. Most induction motors have PF between 0.8-0.9 at full load.

Q4: Why does efficiency matter in the calculation?
A: Efficiency accounts for power losses in the motor. Higher efficiency means less current for the same power output.

Q5: Can I use this for single-phase motors?
A: No, this formula is for three-phase motors. Single-phase motors use a different calculation.