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 under load. This calculation is essential for proper circuit sizing and 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 (0-1)
• \( Efficiency \) — Motor efficiency as a decimal (0-1)

Explanation: The formula accounts for all three phases (√3 factor) and adjusts for power factor (phase difference) and motor efficiency (energy losses).

3. Importance of Current Calculation

Details: Accurate current calculation is crucial for selecting proper wire sizes, circuit breakers, overload protection, and ensuring safe operation of electrical equipment.

4. Using the Calculator

Tips: Enter motor power in kW, line voltage in volts, power factor (typically 0.8-0.95), and motor efficiency (typically 0.85-0.95). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical power factor for motors?
A: Induction motors typically have power factors between 0.8-0.9 at full load, lower when lightly loaded.

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

Q3: What if I know horsepower instead of kW?
A: Convert horsepower to kW by multiplying by 0.746 (1 HP = 0.746 kW).

Q4: Why include efficiency in the calculation?
A: Efficiency accounts for energy losses in the motor - the actual current drawn will be higher than the theoretical value due to these losses.

Q5: Is this calculation valid for single-phase motors?
A: No, single-phase motors use a different formula without the √3 factor.