1. What is 3-Phase Current Calculation?

The 3-phase current calculation determines the current draw of a three-phase motor or electrical system based on power input, voltage, power factor, and efficiency. 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)
• \( \eta \) — Efficiency (0-1)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula accounts for the phase relationship in 3-phase systems 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 performance and longevity.

4. Using the Calculator

Tips: Enter power in watts, line voltage in volts, power factor (typically 0.8-0.95 for motors), and efficiency (typically 0.85-0.95). All values must be positive numbers within their valid ranges.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical power factor for motors?
A: Induction motors typically have 0.85 power factor at full load, dropping to 0.2-0.3 at no load. Synchronous motors can achieve 1.0.

Q2: How does voltage affect current?
A: Current is inversely proportional to voltage. Higher voltage systems draw less current for the same power.

Q3: Why include efficiency?
A: Motors convert electrical to mechanical power. The efficiency factor accounts for losses (heat, friction).

Q4: What's the difference between line and phase voltage?
A: In 3-phase systems, line voltage is between any two lines, while phase voltage is between line and neutral (line voltage = √3 × phase voltage in wye systems).

Q5: Can I use this for single-phase motors?
A: No, single-phase motors use a different formula: I = P / (V × PF × η).