1. What is the kW to Current Calculation?

This calculator determines the current drawn by a three-phase motor given its power rating in kilowatts, operating voltage, and power factor. It's essential for electrical system design and motor protection.

2. How Does the Calculator Work?

The calculator uses the three-phase current formula:

Where:

• \( I \) — Current in amperes (A)
• \( kW \) — Power in kilowatts
• \( V \) — Line voltage in volts
• \( PF \) — Power factor (unitless, between 0 and 1)
• \( \sqrt{3} \) — Constant for three-phase systems (≈1.732)

Explanation: The formula converts kW to watts (×1000), then divides by the product of voltage, power factor, and √3 (phase difference in three-phase systems).

3. Importance of Current Calculation

Details: Knowing the current draw is crucial for selecting proper wire sizes, circuit breakers, overload protection, and ensuring the power supply can handle the motor's requirements.

4. Using the Calculator

Tips:

• Enter motor power rating in kilowatts (nameplate value)
• Use line-to-line voltage for three-phase systems (typically 208V, 230V, 400V, 480V, etc.)
• Power factor is typically 0.8-0.95 for motors (0.85 is a common default)

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between line and phase current?
A: For delta connections, line current is √3 times phase current. For wye connections, they're equal.

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

Q3: Why is power factor important?
A: Lower power factor increases current for the same real power, requiring larger conductors.

Q4: What about single-phase motors?
A: Single-phase formula is I = (kW × 1000)/(V × PF). Remove the √3 factor.

Q5: Should I add a safety margin?
A: Yes, typical practice is to size components for 125% of full-load current.