The performance of a three-phase asynchronous motor is defined by its torque-speed characteristic, a curve that illustrates the relationship between the motor's torque and its rotational speed. This curve shows that the motor produces a substantial amount of starting torque, which is useful for overcoming initial inertia when starting a load. As the rotor accelerates, the torque changes, reaching a maximum value known as the breakdown torque. Understanding this characteristic is crucial for selecting a three-phase asynchronous motor that is well-suited for a particular application, whether it requires high starting torque or stable running performance.

A significant operational parameter for a three-phase asynchronous motor is its slip. Slip is expressed as the relative difference between the synchronous speed of the magnetic field and the actual rotor speed. It is usually given as a percentage of the synchronous speed. Under no load, the slip of a three-phase asynchronous motor is very small, and the rotor speed approaches the synchronous speed. As mechanical load increases, the slip increases, which in turn induces stronger currents in the rotor and produces more torque to handle the load. This self-regulating characteristic contributes to the motor's stable operation.

While a standard three-phase asynchronous motor operates at a nearly constant speed, there are methods available for controlling its velocity. The most common approach is to vary the frequency of the electrical supply using a variable frequency drive (VFD). Since the synchronous speed is directly proportional to the supply frequency, reducing the frequency lowers the motor's base speed. A VFD provides a flexible way to achieve speed control for a three-phase asynchronous motor, enabling processes to operate with adjustable flow or speed, which can lead to energy savings in systems like pumping and ventilation.

The three-phase asynchronous motor is a versatile workhorse found in numerous applications. Its robust construction and self-starting nature make it a reliable choice for constant-speed drives such as compressors, crushers, and conveyor systems. When paired with a VFD, its utility expands to variable-speed applications, including precision machine tools and industrial fans. The combination of functional reliability, manageable operational characteristics, and adaptable control options ensures the continued prominence of the three-phase asynchronous motor in powering industrial machinery.