Failure phenomenon: Centrifuge is a must for hospitals and research institutions of the

    One of the important equipment, it will have a direct impact on the quality of being centrifugal centrifugal material, "I am a speed of instability in the maintenance of centrifuges, they found both high-speed or low speed is not stable"

    Troubleshooting: The centrifuge is a DC-type speed control motors, the speed of change through the adjustable resistor thyristor's conduction angle of thyristor controlled rectifier by the motor arrived at both ends of the voltage in order to achieve control The purpose of speed "motor speed instability, from the principles of the analysis, the following four cases, there may be"

    (1) adjustable resistance, due to adjustable resistor installed on the control panel, use the frequency is very high, a long time, there is very poor contact of the ordinary "

    (2) SCR are also many problems, usually breakdown short circuit, open circuit and can not trigger or internal connection is bad, etc. "

    (3) four rectifier diodes in a only a problem "

    (4) between the rotor and the commutator itself is bad toner or Brush and other "first in line with the principles of the easier repairs, first of all measurements adjustable resistance, resistance with the regulation while the changes in the law to prove that potentiometer is a good "re-measurement of silicon have also found no problems" in the measurement of four rectifier diodes, we found that there is a good times and bad, because the diode is a high-current gold seal tube "end of the screw fastening the circuit board, and the other one with the wire soldered to the board "from the circuit board removed, we found a loose positive and negative phenomena, and then measure the side while shaking, confirmed that the diode good times and bad," as the tube model can not see, put the same size pipe installed, electricity boot speed very quickly that the tube just breakdown, remove the measure remains intact, "Measurement of the other three diodes are normal", but in more measured, we found two kinds of models of positive and negative polarity opposite diode (that is, one end of the screw has a positive polarity, and also negative in nature) "Therefore, we must pay attention during installation is best to use the same model with the specification of components," When put on the same model with the specification of components, the power test machine Everything back to normal "