In scientific research on the speed of centrifugal fans, they are generally considered as variable-speed DC motors, with their speed primarily adjusted through variable resistors. By placing a controllable rectifier on both sides of the motor, it is possible to control the speed of the centrifugal fan. But do you know what causes the instability in speed if it occurs?
On one hand, it's likely that there are some difficulties with the diodes in the four rectifiers of the centrifugal fan, which are affecting the overall efficiency of the equipment. On the other hand, it may be that the carbon powder in the motor rotor and commutator, or the motor carbon brushes themselves, are not equal. In this case, let's first take a look at the adjustable resistor of the centrifugal fan; if the resistance value changes with the adjustment, it's a good sign.
On the other hand, the issue might likely arise from the thyristors, as phenomena such as poor guidance, contact failure, short circuit faults, and un-touchability are all reasons for the instability in speed. Additionally, if there is a contact failure with the adjustable resistor, the reliability of the speed will also be affected.
