Motor Power (kW) from Amps and Voltage Calculator

Motor Power Formula:

\[ kW = \frac{Voltage \times Current \times Power\ Factor \times Efficiency}{1000} \]

Voltage (V):

Current (A):

Power Factor:

(0-1)

Efficiency:

(0-1)

Motor Power:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Motor Power Calculation?

The motor power calculation determines the actual power output of an electric motor in kilowatts (kW) based on voltage, current, power factor, and efficiency. This is essential for proper motor sizing and electrical system design.

2. How Does the Calculator Work?

The calculator uses the motor power formula:

\[ kW = \frac{Voltage \times Current \times Power\ Factor \times Efficiency}{1000} \]

Where:

\( Voltage \) — Line voltage in volts (V)
\( Current \) — Current draw in amperes (A)
\( Power\ Factor \) — Ratio of real power to apparent power (0-1)
\( Efficiency \) — Motor efficiency as a decimal (0-1)

Explanation: The formula calculates real power output by accounting for both the power factor (phase difference between voltage and current) and the motor's energy conversion efficiency.

3. Importance of Motor Power Calculation

Details: Accurate motor power calculation is crucial for proper equipment selection, electrical system design, energy efficiency assessments, and compliance with electrical codes.

4. Using the Calculator

Tips: Enter voltage in volts, current in amps, power factor (typically 0.8-0.95 for motors), and efficiency (typically 0.85-0.95 for most motors). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical power factor for electric motors?
A: Induction motors typically have power factors between 0.80-0.95 at full load, lower at partial loads. Synchronous motors can achieve unity (1.0) power factor.

Q2: How do I find my motor's efficiency?
A: Check the motor nameplate or manufacturer specifications. Standard efficiency motors are typically 85-95% efficient.

Q3: Is this calculation valid for 3-phase motors?
A: For 3-phase motors, multiply by √3 (1.732) and use line-to-line voltage. The formula becomes: \( kW = \frac{\sqrt{3} \times V_{LL} \times I \times PF \times Eff}{1000} \)

Q4: Why is power factor important?
A: Low power factor increases current for the same real power, leading to larger conductors, higher losses, and potential utility penalties.

Q5: What affects motor efficiency?
A: Efficiency depends on motor design, size, load percentage, quality of materials, and operating conditions like temperature.