1. What is a Motor kW to Current Calculator?

Definition: This calculator estimates the current drawn by a three-phase motor based on its power rating in kilowatts, system voltage, and power factor.

Purpose: It helps electrical engineers and technicians determine the current requirements for motor sizing, cable selection, and protection devices.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Current (amps)
• \( P_{kW} \) — Motor power (kilowatts)
• \( V \) — Voltage (volts)
• \( PF \) — Power factor (0-1)

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

3. Importance of Current Calculation

Details: Accurate current calculation ensures proper sizing of cables, circuit breakers, and overload protection, preventing equipment damage and ensuring safety.

4. Using the Calculator

Tips: Enter the motor power in kW, system voltage (default 400V), and power factor (default 0.85). All values must be > 0, with PF between 0.1 and 1.

5. Frequently Asked Questions (FAQ)

Q1: Why is the power factor important?
A: Power factor represents the efficiency of power usage. Lower PF means higher current for the same real power.

Q2: What's a typical power factor for motors?
A: Induction motors typically have PF between 0.8-0.9 at full load, lower at partial loads.

Q3: Does this work for single-phase motors?
A: No, for single-phase use \( I = \frac{P_{kW} \times 1000}{V \times PF} \) (remove √3).

Q4: How does voltage affect current?
A: Higher voltage reduces current for the same power (inverse relationship).

Q5: Should I use full load current or running current?
A: For protection devices, use full load current plus safety margin. Starting current is typically 5-7× higher.