5.5kW 3-Phase Motor Amps Calculator

3-Phase Motor Current Formula:

\[ Current (A) = \frac{5.5 \times 1000}{\sqrt{3} \times Voltage \times Power\ Factor \times Efficiency} \]

Current (A):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is 3-Phase Motor Current Calculation?

The 3-phase motor current calculation determines the amperage drawn by a 5.5kW three-phase electric motor based on supply voltage, power factor, and motor efficiency. This is essential for proper circuit sizing and protection.

2. How Does the Calculator Work?

The calculator uses the 3-phase power formula:

\[ Current (A) = \frac{5.5 \times 1000}{\sqrt{3} \times Voltage \times Power\ Factor \times Efficiency} \]

Where:

5.5 — Motor power rating in kilowatts (kW)
1000 — Conversion factor (kW to watts)
√3 — Constant for three-phase systems (≈1.732)
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 converts kW to watts, then divides by the product of voltage, power factor, and efficiency to find current.

3. Importance of Current Calculation

Details: Accurate current calculation is crucial for selecting proper wire sizes, circuit breakers, and overload protection devices to ensure safe motor operation and prevent equipment damage.

4. Using the Calculator

Tips:

Enter line-to-line voltage (typically 400V for many industrial systems)
Power factor is usually between 0.8-0.95 for motors
Motor efficiency typically ranges from 0.85-0.95
All values must be positive numbers

5. Frequently Asked Questions (FAQ)

Q1: Why is power factor important in this calculation?
A: Power factor accounts for the phase difference between voltage and current. Lower power factor means higher current for the same real power.

Q2: What's a typical current for a 5.5kW motor at 400V?
A: With PF=0.85 and efficiency=0.9, about 10.3A. Actual current may vary based on specific motor characteristics.

Q3: How does voltage affect the current?
A: Current is inversely proportional to voltage. Higher voltage means lower current for the same power.

Q4: Should I use this for single-phase motors?
A: No, single-phase motors use a different formula without the √3 factor.

Q5: How accurate is this calculation?
A: It provides a good estimate, but actual current may vary due to motor design, load conditions, and temperature.