As a kind of purification equipment, FFU is currently widely used in various cleaning projects. The full name of FFU is called Fan Filter Unit "Fan Filter Unit", which is the clean equipment that can provide power by connecting the fan and filter together. As early as the 1960s, the world's first laminar flow clean room The application of FFU has already begun to appear after the establishment. At present, FFU generally uses single-phase multi-speed AC motors, three-phase multi-speed AC motors and DC motors. The power supply voltage of the motor is roughly 110V, 220V, 270V, and 380V. The control methods are mainly divided into the following types: ◆ Multi-gear switch control ◆ Continuous speed adjustment control ◆ Computer control The FFU control system is a set of distributed control system, which can easily realize the functions of on-site distributed control and centralized management. It can flexibly control the start-stop and wind speed of each fan in the clean room. The control system uses repeater technology to solve the problem of limited 485 drive capacity and can control unlimited fans. This control system includes the following four parts: ◆ On-site intelligent controller ◆ Wired centralized control mode ◆ Remote control mode ◆ System comprehensive function With the rapid development of high-tech industries, there will be more and more clean rooms using FFU on a large scale. Centralized control of FFU in the clean room will also be an issue that designers and owners must pay attention to.