Motor torque is a fundamental concept in electromechanical systems and is essential for understanding how motors convert electrical energy into rotational mechanical energy. Torque is the rotational equivalent of force—it’s what causes an object to rotate around an axis.
In simple terms, torque (T) is defined as the twisting force that causes rotation. In electric motors, torque is produced by the interaction of the magnetic field and the current in the windings. It’s measured in Newton-meters (Nm).
The torque output of a motor depends on the amount of current flowing through it, the strength of the magnetic field, and the geometry of the motor itself.
T (Nm) = (9550 × Power (kW)) / Speed (RPM)
This equation provides the torque from known motor power and speed. It assumes steady-state conditions (no acceleration), ideal efficiency, and negligible friction losses.
Torque plays a vital role in determining the ability of a motor to move or lift loads. Applications like conveyors, cranes, and compressors require specific torque outputs to function correctly.
Real motors are not 100% efficient. When calculating torque from actual measured power (input), it's important to account for losses due to heat, friction, and magnetic hysteresis.
Some motors are designed for high torque at low speed (e.g., gear motors), while others favor high speed with lower torque. Variable frequency drives (VFDs) can also control torque and speed dynamically.
In summary, torque calculation is essential for designing, selecting, and operating electric motors across industrial, automotive, and commercial settings.