1. What is the 3 Phase Motor Calculation Formula?

The 3 Phase Motor Calculation Formula estimates the current drawn by a three-phase motor given its power rating, supply voltage, power factor, and efficiency. This is essential for proper electrical system design and protection.

2. How Does the Calculator Work?

The calculator uses the 3-phase motor current formula:

Where:

• \( I \) — Current in amperes (A)
• \( P \) — Power in watts (W)
• \( V \) — Line voltage in volts (V)
• \( PF \) — Power factor (dimensionless, 0-1)
• \( eff \) — Motor efficiency (dimensionless, 0-1)

Explanation: The formula accounts for the three-phase power relationship and includes factors for power factor and motor efficiency.

3. Importance of Current Calculation

Details: Accurate current calculation is crucial for selecting proper wire sizes, circuit breakers, overload protection, and ensuring safe operation of motor-driven equipment.

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 is a typical power factor for motors?
A: Induction motors typically have power factors between 0.8 and 0.9 at full load, lower at partial loads.

Q2: How does voltage affect motor current?
A: Current is inversely proportional to voltage - higher voltage means lower current for the same power.

Q3: What is motor efficiency?
A: Efficiency is the ratio of mechanical power output to electrical power input, typically 85-95% for modern motors.

Q4: Should I use nameplate values?
A: For most accurate results, use the motor's nameplate voltage, power factor, and efficiency ratings.

Q5: How does this differ from single-phase calculation?
A: Single-phase formula is I = P/(V×PF×eff) without the √3 factor.