1. What is 3 Phase Motor Current?

The 3 phase motor current calculation determines the amperage drawn by a 7.5kW three-phase electric motor based on supply voltage, power factor, and motor efficiency. This is essential for proper circuit design and protection.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Current in amperes (A)
• \( V \) — Line-to-line voltage (V)
• \( PF \) — Power factor (0 to 1, typically 0.8-0.95)
• \( Eff \) — Motor efficiency (0 to 1, typically 0.85-0.95)

Explanation: The formula converts kW to watts (×1000), accounts for three-phase power (√3), and adjusts for power factor and efficiency 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 the motor.

4. Using the Calculator

Tips: Enter line-to-line voltage in volts, power factor (typically 0.85 for motors), and efficiency (typically 0.9). All values must be positive (voltage > 0, 0 < PF ≤ 1, 0 < Eff ≤ 1).

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 at partial loads.

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

Q3: What's a typical motor efficiency?
A: Modern three-phase motors are typically 85-95% efficient at full load.

Q4: Why is √3 used in the formula?
A: √3 (≈1.732) is the ratio between line and phase quantities in three-phase systems.

Q5: Should I add a safety margin?
A: Yes, it's common to add 25% margin for startup current and design safety.