1. What is 3-Phase Motor Current?

The 3-phase motor current is the amount of electrical current drawn by a three-phase motor when operating under load. It's essential for proper circuit sizing and motor protection.

2. How Does the Calculator Work?

The calculator uses the 3-phase current formula:

Where:

• \( I \) — Current in amps
• \( P \) — Power in watts
• \( V \) — Line voltage in volts
• \( PF \) — Power factor (0-1)
• \( \eta \) — Motor efficiency (0-1)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula accounts for the three-phase power distribution 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 motor longevity.

4. Using the Calculator

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

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 1.0 PF.

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

Q3: Should I use line-to-line or line-to-neutral voltage?
A: Always use line-to-line (phase-to-phase) voltage for 3-phase calculations.

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

Q5: Why does current increase when voltage drops?
A: To maintain the same power output, current must increase when voltage decreases (P = V×I×PF×√3).