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

The 3-phase motor current formula calculates the full load current of an AC electric motor. It accounts for the motor's power rating, supply voltage, power factor, and efficiency to determine the current draw.

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)
• \( \eta \) — Efficiency (0-1)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula divides the real power by the product of voltage, power factor, and efficiency to determine the actual current drawn by the motor.

3. Importance of Current Calculation

Details: Calculating full load current is essential for proper wire sizing, circuit breaker selection, overload protection, and overall electrical system design.

4. Using the Calculator

Tips: Enter power in watts, voltage in volts, power factor (typically 0.8-0.95), and efficiency (typically 0.85-0.95). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical power factor for motors?
A: Induction motors typically have 0.85-0.90 PF at full load, lower at partial loads. Synchronous motors can achieve 1.0 PF.

Q2: How do I convert horsepower to watts?
A: 1 HP = 746 watts. Multiply horsepower 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: What voltage should I use for line-to-line or line-to-neutral?
A: Always use line-to-line (phase-to-phase) voltage for 3-phase calculations.

Q5: How accurate is this calculation?
A: It provides theoretical full-load current. Actual current may vary due to voltage fluctuations, temperature, and motor condition.