Plant Operation Test 2025 – 400 Free Practice Questions to Pass the Exam

A variable frequency drive (VFD) primarily controls the speed and torque of an electric motor by varying the frequency and voltage of the electrical power supplied to the motor. This adjustment allows for precise control over motor functions, enabling it to operate efficiently across various conditions. By changing the frequency, the VFD effectively alters the motor's speed, and by adjusting the voltage in conjunction with the frequency, it also controls the torque output. This capability is essential in applications where variable speed is crucial for process control, energy savings, and performance optimization.

The regulation of voltage alone is insufficient for achieving the functionality that a VFD provides, as it does not account for the necessary adjustments in motor speed or torque. A VFD is not a communication device, as its primary role is not to facilitate information exchange but rather to control power delivery to the motor. Additionally, providing backup power during emergencies is not a function of a VFD; such tasks would typically be managed by uninterruptible power supplies (UPS) or generators, which are designed for power reliability rather than motor speed control.