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 specific conditions. It's essential for proper circuit sizing and protection device selection.

2. How Does the Calculator Work?

The calculator uses the standard 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 (approximately 1.732)

Explanation: The formula converts kW to watts, then divides by the product of voltage, power factor, and efficiency to find the current.

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 motor power in kW, line voltage in volts, and typical power factor (0.85) and efficiency (0.95) if unknown. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between line current and phase current?
A: For a delta connection, line current equals √3 times phase current. For a star connection, line current equals phase current.

Q2: Why is power factor important?
A: Lower power factor means higher current for the same real power, increasing losses and requiring larger conductors.

Q3: What are typical power factor values for motors?
A: Typically 0.8-0.95 at full load, lower at partial loads. Always check motor specifications.

Q4: How does voltage affect current?
A: Current is inversely proportional to voltage. Higher voltage means lower current for the same power.

Q5: Should I use this for motor starting current?
A: No, starting current (inrush current) is typically 5-7 times full load current and lasts only briefly.