1. What is Phase Current in 3-Phase AC Motors?

Phase current is the current flowing through each individual phase in a three-phase AC induction motor. It's a critical parameter for motor sizing, protection device selection, and electrical system design.

2. How Does the Calculator Work?

The calculator uses the 3-phase current formula:

Where:

• \( I \) — Phase current (Amperes)
• \( P \) — Real power (Watts)
• \( V \) — Line-to-line voltage (Volts)
• \( PF \) — Power factor (unitless, 0-1)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula accounts for the balanced three-phase power system where power is distributed across three phases.

3. Importance of Phase Current Calculation

Details: Accurate current calculation is essential for proper wire sizing, circuit breaker selection, motor protection, and energy efficiency analysis in three-phase systems.

4. Using the Calculator

Tips: Enter power in watts, line-to-line voltage in volts, and power factor (typically 0.8-0.95 for motors). All values must be positive (power > 0, voltage > 0, 0 < PF ≤ 1).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between line current and phase current?
A: In star (wye) configuration, line current equals phase current. In delta configuration, line current is √3 times phase current.

Q2: What is a typical power factor for AC motors?
A: Induction motors typically have power factors between 0.8-0.95 at full load, lower at partial loads.

Q3: Should I use line-to-line or line-to-neutral voltage?
A: Always use line-to-line voltage for this calculation in three-phase systems.

Q4: How does motor efficiency affect the calculation?
A: The formula uses real power (input power × efficiency). For output power, divide by efficiency.

Q5: What about motor starting current?
A: Starting current (inrush) is typically 5-7 times full load current but brief (seconds). Not calculated by this formula.