1. What is 3-Phase Motor Current?

The current drawn by a 3-phase motor depends on the motor's power rating, supply voltage, power factor, and efficiency. For a 7.5kW motor, this calculator determines the line current required for operation.

2. How Does the Calculator Work?

The calculator uses the 3-phase power formula:

Where:

• \( I \) — Line current in amps
• \( V \) — Line voltage in volts
• \( PF \) — Power factor (0-1)
• \( \eta \) — Motor efficiency (0-1)
• 7500 — Motor power rating in watts (7.5kW)

Explanation: The formula accounts for the three-phase power relationship where power is divided by the product of √3, voltage, power factor, and efficiency to get current.

3. Importance of Current Calculation

Details: Knowing the motor current is essential for proper wire sizing, circuit breaker selection, overload protection settings, and overall electrical system design.

4. Using the Calculator

Tips: Enter the line-to-line voltage in volts, power factor (typically 0.8-0.95), and motor efficiency (typically 0.85-0.95 for most industrial motors). All values must be positive.

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 efficiency for 7.5kW motors?
A: Modern 7.5kW motors typically have 88-92% efficiency at full load.

Q4: Is this for star or delta connection?
A: The formula works for both connections as it uses line voltage and line current.

Q5: How accurate is this calculation?
A: It provides theoretical full-load current. Actual current may vary based on load conditions, temperature, and motor condition.