The efficiency of an electric motor is a measure of how effectively it converts electrical power into mechanical power. It indicates how much of the input electrical energy is converted into useful output mechanical energy, while the rest is lost as heat and other inefficiencies. Efficiency is expressed as a percentage and can be calculated using the following formula:
Efficiency = (Output Power / Input Power) × 100%
Where:
Output Power: This is the mechanical power output of the motor, usually measured in watts (W) or kilowatts (kW). It can be calculated using the formula:
Output Power = Torque × Angular Speed
Torque is the rotational force produced by the motor and is typically measured in Newton-meters (Nm).
Angular Speed is the rotational speed of the motor in radians per second (rad/s).
Input Power: This is the electrical power input to the motor, usually measured in watts (W) or kilowatts (kW). It can be calculated using the formula:
Input Power = Voltage × Current
Voltage is the electrical potential difference applied to the motor, measured in volts (V).
Current is the electrical current flowing through the motor, measured in amperes (A).
To calculate the efficiency, you need to measure or determine the output power and input power of the electric motor. The accuracy of the efficiency calculation depends on the accuracy of the measurements.
Keep in mind that the efficiency of an electric motor may vary under different operating conditions and loads. Manufacturers often provide efficiency curves that show how efficiency changes at different operating points. Additionally, losses due to friction, windage, and other factors might not be accounted for in this basic efficiency calculation but are considered in more detailed analyses.