Troubleshooting of unstable speed of the hottest c

Troubleshooting of centrifuge speed instability

troubleshooting of centrifuge speed instability

fault phenomenon: centrifuge is one of the indispensable

important equipment in hospitals and scientific research institutions, and its quality directly affects the centrifugal quality of the centrifuged objects. "When I overhaul a centrifuge with unstable speed, I found that it is unstable both at high speed and low speed"

Troubleshooting: the centrifuge is a DC speed regulating motor, The speed is to change the conduction angle of the thyristor through the adjustable resistance, and then the thyristor controls the voltage at both ends of the motor after rectification, so as to achieve the purpose of controlling the speed. "The motor speed is unstable. In principle, it is a component for measuring the experimental force, and the following four situations are possible"

(1) the adjustable resistance, because the colorless transparent The high toughness and high strength polymer that can be quickly self repaired can be installed on the control panel no matter what steps are taken. It is used very frequently and for a long time, Poor contact is common. "

(2) there are also many problems with the thyristor, usually breakdown, short circuit, open circuit, unable to trigger or poor internal contact."

(3) one of the four rectifier diodes only has the problem "

(4) there is carbon powder between the motor rotor and the commutator or or the carbon brush itself is bad." based on the principle of easy repair first, measure the adjustable resistance first, and the resistance changes regularly with the adjustment, It is proved that the potentiometer is good. "No problem is found when measuring the thyristor again." when measuring four rectifier diodes, one is found to be good and bad. Because the diode is a high current gold sealed tube, "one end is screwed on the circuit board, and the other end is welded to the circuit board with wire". When removing it from the circuit board, it is found that the positive and negative poles are loose, and then shake while measuring, It was confirmed that the diode was good and bad. "Because the tube model could not be seen clearly, the tube of the same specification was installed, and the power on and startup speed was very fast. It was considered that the rigid tube had broken down, and the removal and measurement were intact." the measurement of the other three diodes was also normal. "But in the comparative measurement, it was found that the positive and negative polarity of the two types of diodes were completely opposite (that is, the end of the upper screw had positive polarity 7, the displacement resolution (mm):0.0025mm, and also negative polarity)." Therefore, during installation, it must be noted that it is best to use components of the same model and specification. "When replacing components of the same specification and model, power on and test the machine, and everything returns to normal."