Low speed refrigerationCommon faults and solutions of centrifuge
Centrifuge is a kind of mechanical equipment that uses centripetal force to separate liquid and solid particles or liquid and liquid compounds. The centrifuge used in medicine is called medical centrifuge. Medical centrifuges can be divided into low-speed centrifuges according to the larger speed; The results showed that the speed of centrifuges was 10000 R / min, rapid centrifuges (10000-30000 R / min) and speed limited centrifuges (& gt; According to whether there is refrigeration equipment, it can be divided into refrigerated centrifuge and ordinary centrifuge.
The paper summarizes the fault condition and maintenance methods encountered in the maintenance of equipment. For example: the low emergency refrigerated centrifuge is a suction filter laboratory instrument with a speed of 4000r/min, and the key to the failure condition includes the centrifuge not rotating or the speed is not accurate, and the temperature control is not good.
1．Fault one
1.1 Fault condition
If the centrifuge doesn't work, the speed can't reach the preset value.
1.2 Understanding and testing
There are three reasons why the centrifuge does not rotate and the speed cannot reach the preset value
（1）Part of the circuit is faulty. First, the power plug, power socket, power plug, electromagnetic relay（WH118，3.5kΩ，2W）、Automobile relay（HH52P，HH53P）The vulnerable components shall be tested. Then, the power transformer will be tested for future power supply circuit, air leakage switch, electronic rectifier, filter, transformer（OUT18V，2A），Until part of the motor.

（2）The motor itself is dead. The motor is one of the irreplaceable components of the centrifuge. The motor is divided into motor with carbon brush and motor without carbon brush. The centrifuge is a carbon brush motor with motor, and now most motors are all brushless motors without motor. The motor speed can't be set. First, check the rolling bearing. When it needs to be replaced, replace it. When it must be maintained (such as filling grease and cleaning), maintain it. Then, the matching of motor commutator and carbon brush, the strong loss of carbon brush and the necessity of replacement are detected.
（3）Part of the speed control is faulty. The automatic speed control system has an integrated IC (cw7814ciii9501), which can ensure the safe and accurate operation of the centrifuge. If the speed fault is cleared, the integrated IC or operation panel can be replaced.
2．Fault 2
2.1 Fault condition
Centrifuge temperature control is not effective, although it can cool, but do not set the temperature.
2.2 Understanding and testing
The key factors for the temperature of centrifuge are two factors:
（1）Temperature operation panel failure;
（2）Sensor failure. Temperature is one of the key parameters of refrigerated centrifuge. Because some samples (such as somatic cells, proteins, etc.) can be destroyed in high temperature natural environment, the centrifuge will cause kinetic energy when it runs rapidly. Therefore, it is necessary to apply refrigeration unit to reduce the temperature of sample, so as to keep the natural environment within a certain range (such as 1 ~ 10 ℃). Open the cover of the main engine box and check that the working voltage of the temperature operation panel, 12V and 6V are normal. It was suspected that the temperature control integrated IC (icl7107cpl9646) was abnormal. There was a temperature control integrated IC (icl7107cpl58840) removed from the damaged old equipment. After replacement, the centrifuge fault was cleared and the equipment recovered. If the sensor failure leads to inaccurate temperature measurement, and the wrong data information leads to random power on / off of the refrigeration unit, it is necessary to replace the sensor encapsulated in the centrifuge body field.
3．Fault 3
3.1 Fault condition
Centrifuge temperature setting is normal, but do not refrigerate.
3.2 Understanding and testing
There are two reasons for normal temperature setting but no refrigeration
（1）Clear the temperature operation panel fault, suspect the refrigeration unit fault, because the application staff reflect that the centrifuge cooling effect is poor in a few days, after detection found that the air compressor air conditioning Freon is too little, resulting in poor temperature reduction effect. Fill the refrigeration compressor with air conditioner freon and clear the fault.
（2）Sensor fault, fault two has long been described, no more details.
4．Maintenance of centrifuge
（1）Before the application, the centrifuge was placed on a firm road, so the human body could not shake around, and the centrifuge was connected after the switch power supply and other field equipment had no fault. The test sample should be balanced when loading, because the large centripetal force will be caused when the L-band is running, especially when the test sample is running rapidly, the unbalanced test sample will cause large torque, which will cause the equipment to tremble or shake, or distort the transmission shaft to cause higher shaking and fracture. After turning on the main power switch, set the speed from low gear to rapid and gradual acceleration. At this time, it is strictly forbidden to open the hood. In actual operation, if you find any abnormality, you need to cut off the power immediately. You don't have to wait for more serious harm before you stand by. You should contact the technical engineer of diagnosis and treatment equipment maintenance as soon as possible. At the end of the test, the speed should be reduced gradually until the power is cut off.
（2）The technical engineer of diagnosis and treatment equipment maintenance shall timely carry out replacement of the components which are very easy to consume, such as motor brushes, fill the rolling bearing with grease, detect and repair the electronic devices which are very easy to damage, and ensure that the equipment is in normal operation and prevent from the unexpected.