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

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

2. How Does the Calculator Work?

The calculator uses the 3-phase current equation:

Where:

• \( I \) — Current in amps
• \( P \) — Power in watts
• \( V \) — Line voltage in volts
• \( PF \) — Power factor (unitless, 0-1)
• \( \eta \) — Motor efficiency (decimal, 0-1)

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

3. Importance of Current Calculation

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

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 0.8-0.95 at full load, lower at partial loads.

Q2: How do I find my motor's efficiency?
A: Check the motor nameplate or manufacturer specifications. Standard efficiency motors are typically 85-95% efficient.

Q3: Should I use line-to-line or line-to-neutral voltage?
A: Use line-to-line voltage for this calculation (the higher voltage in a 3-phase system).

Q4: What if my motor power is in horsepower?
A: Convert horsepower to watts (1 HP = 746 watts) before using this calculator.

Q5: Why is the current higher than expected?
A: Low power factor or efficiency values will increase calculated current. Verify all input values are correct.