Motor Full Load Current (FLC) Calculator

Motor FLC Formula:

\[ FLC = \frac{Power \times 1000}{Voltage \times \sqrt{3} \times Power\ Factor \times Efficiency} \]

Power:

Voltage:

Power Factor:

(0-1)

Efficiency:

(0-1)

Full Load Current (FLC):

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1. What is Motor Full Load Current?

Full Load Current (FLC) is the current drawn by an electric motor when operating at its rated power, voltage, and frequency under full load conditions. It's a crucial parameter for selecting proper wire sizes, circuit breakers, and overload protection devices.

2. How Does the Calculator Work?

The calculator uses the FLC formula for three-phase AC motors:

\[ FLC = \frac{Power \times 1000}{Voltage \times \sqrt{3} \times Power\ Factor \times Efficiency} \]

Where:

\( Power \) — Motor rated power in kilowatts (kW)
\( Voltage \) — Line-to-line voltage in volts (V)
\( Power\ Factor \) — Ratio of real power to apparent power (0-1)
\( Efficiency \) — Motor efficiency as decimal (0-1)

Explanation: The formula converts kW to watts (×1000), accounts for three-phase power (√3), and adjusts for power factor and efficiency losses.

3. Importance of FLC Calculation

Details: Accurate FLC calculation is essential for proper motor protection, preventing overheating, and ensuring electrical system safety. It helps in selecting appropriate circuit breakers, fuses, and overload relays.

4. Using the Calculator

Tips: Enter motor power rating in kW, operating voltage in volts, typical power factor (usually 0.8-0.95), and motor efficiency (usually 0.85-0.95 for standard efficiency motors).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between FLC and starting current?
A: Starting current (inrush current) is typically 5-7 times higher than FLC but lasts only a few seconds during motor startup.

Q2: How does voltage affect FLC?
A: FLC is inversely proportional to voltage. Higher voltage means lower current for the same power.

Q3: What are typical power factor values for motors?
A: Induction motors typically have 0.85-0.9 PF at full load, lower at partial loads. Synchronous motors can achieve unity (1.0) 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 this be used for single-phase motors?
A: No, single-phase motors use a different formula without the √3 factor.