1. What is the 3-Phase Motor Current Formula?

The 3-phase motor current formula calculates the current drawn by a three-phase AC motor given its power rating, supply voltage, power factor, and efficiency. This is essential for proper motor sizing and circuit protection.

2. How Does the Calculator Work?

The calculator uses the 3-phase current formula:

Where:

• \( I \) — Current in amps
• \( P \) — Power in watts
• \( V \) — Voltage in volts
• \( PF \) — Power factor (unitless, 0-1)
• \( \eta \) — Efficiency (decimal, 0-1)

Explanation: The formula accounts for the three-phase power system (√3 factor) and the motor's power factor and efficiency.

3. Importance of Motor Current Calculation

Details: Accurate current calculation is crucial for selecting proper wire sizes, circuit breakers, overload protection, and motor starters.

4. Using the Calculator

Tips: Enter power in watts, voltage in volts, power factor (typically 0.8-0.95), and efficiency (typically 0.9-0.95 for most motors).

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, lower at partial loads. Synchronous motors can achieve unity (1.0) PF.

Q2: How do I convert horsepower to watts?
A: 1 HP = 746 watts. Multiply HP by 746 before entering in calculator.

Q3: Why is efficiency important?
A: Efficiency accounts for power losses in the motor. Higher efficiency motors draw less current for the same output power.

Q4: Can I use this for single-phase motors?
A: No, single-phase motors use a different formula without the √3 factor.

Q5: What affects motor current most?
A: Voltage has the greatest inverse effect - halving voltage doubles current. Load affects current proportionally.