How to Calculate Power Consumption of an Electric Motor

Calculating power consumption for an electric motor is an important step in understanding its efficiency and determining the associated costs. This guide will walk you through the process of calculating power consumption, providing a clear explanation and some frequently asked questions at the end.

Step 1: Gather the Required Information

Before diving into the calculations, ensure you have the necessary information:

  • Motor Power (P): The rated power of the motor, usually expressed in kilowatts (kW).
  • Line Voltage (V): The voltage at which the motor is connected, typically given in volts (V).
  • Line Current (I): The current drawn by the motor, usually measured in amperes (A).
  • Power Factor (PF): The power factor of the motor, which indicates the efficiency of electrical power utilization. It ranges from 0 to 1.

Step 2: Calculate Power Consumption

The formula for calculating power consumption (PC) is:

    PC = P / (PF * √3 * V * I)


  • P: Motor Power
  • PF: Power Factor
  • V: Line Voltage
  • I: Line Current
  • √3: Square root of 3 (a constant value for three-phase power calculations)

By plugging in the values of P, PF, V, and I, you can calculate the power consumption of the electric motor.

Frequently Asked Question:

Q: Why is power factor important?

Power factor is important because it measures how effectively electrical power is being used. A higher power factor indicates efficient utilization of electrical power, while a lower power factor suggests wastage. It is crucial to consider the power factor when calculating power consumption, as it directly affects energy efficiency and costs.

Remember to always double-check the values and units used for accurate calculations. Now that you understand the process, you can easily calculate the power consumption of an electric motor. This information is valuable for assessing efficiency, estimating operational costs, and making informed decisions regarding motor usage.