When researching the speed of a centrifugal fan, it can usually be regarded as a DC speed-regulating motor, and its speed is mainly changed by using an adjustable resistor. As long as the controllable rectification is applied to both ends of the motor, the speed of the centrifugal fan can be controlled. However, if the speed becomes unstable, what are the reasons for this?

On the one hand, there may be some problems among the four rectifier diodes of the centrifugal fan, which will affect the function of the whole device.

On the other hand, perhaps the carbon powder on the motor rotor and commutator or the carbon brushes themselves are not evenly distributed. At this time, you can first check the adjustable resistor of the fan. If the resistance value changes with the adjustment, it is in good condition.

On the third hand, the problem may lie in the thyristor. Phenomena such as open circuit, poor contact, short circuit, and inability to touch are all reasons for the instability of the speed. In addition, if the adjustable resistor has poor contact, the stability of the speed will also be affected.