1. What is 3-Phase Motor Current?

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

2. How Does the Calculator Work?

The calculator uses the 3-phase current formula:

Where:

• \( Power \) — Motor power rating in kilowatts (kW)
• \( Voltage \) — Line-to-line voltage in volts (V)
• \( Power\ Factor \) — Ratio of real power to apparent power (typically 0.8-0.95)
• \( Efficiency \) — Motor efficiency as a decimal (typically 0.85-0.95)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula converts kW to watts, accounts for 3-phase power characteristics, and adjusts for power factor and motor efficiency losses.

3. Importance of Current Calculation

Details: Accurate current calculation is essential for proper wire sizing, circuit breaker selection, overload protection, and ensuring motor performance within specifications.

4. Using the Calculator

Tips: Enter motor power in kW, line voltage in volts, and typical power factor (0.85) and efficiency (0.90) if unknown. All values must be positive numbers.

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, lower at partial loads. Synchronous motors can achieve 1.0.

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

Q3: Why include efficiency?
A: Efficiency accounts for power losses in the motor. A 90% efficient motor draws more current than a 95% efficient one for the same output.

Q4: Is this for full load current?
A: Yes, this calculates full load amps (FLA). Actual current varies with load.

Q5: What about single-phase motors?
A: Single-phase motors use a different formula without the √3 factor.