What type of motor control is typically used for applications requiring precise speed control?

Variable frequency drives (VFDs) are commonly used for applications that require precise speed control. This is primarily because VFDs can adjust the frequency of the electrical supply to the motor, which directly influences the speed at which the motor runs. By changing the frequency, VFDs can provide smooth acceleration and deceleration, as well as maintain a steady speed under varying load conditions. Additionally, they offer the ability to fine-tune the motor's performance for specific applications, enhancing efficiency and reducing wear on the mechanical components of the system.

In contrast, contact-start control and DOL (Direct On Line) starting provide a simple way to start motors but do not allow for effective control of motor speed once the motor is running. Star-delta starters are designed to reduce the starting current of large motors but primarily focus on starting methods rather than precise speed control during operation. Thus, in applications demanding careful speed regulation, VFDs are the most suitable choice.