Centrifuge maintenance

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The company's centrifuges have been experiencing frequent malfunctions recently. Four of the total 10 centrifuges in the workshop have malfunctioned, and we had to contact the manufacturer to deal with them. In the early stage of the workshop, the reaction centrifuge frequently stopped due to excessive current during startup. Observe that the current of the frequency converter jumps between 20-25A after the centrifuge is started. After about 10 seconds, the frequency converter displays overload protection and shuts down. Other centrifuges that were running normally had a maximum current of 12A during variable frequency startup. After normal operation, it was about 10A. Based on this, it was judged that the motor load was too large, so the workshop was asked to empty the centrifuge and test it without load. The result was that the current was also high, and the overload protection triggered a trip. However, manual turning is very easy, and there is no obvious jamming or lag. I initially suspected that the inverter might be faulty, so I contacted the inverter manufacturer to modify the inverter parameters, but the problem persisted. Then the abnormal power cord of the centrifuge was connected to the frequency converter of the normally operating centrifuge, but the fault remained. Therefore, it is suspected that there is a problem with the motor itself. After the manufacturer arrived, he disassembled the machine and found that the no-load rotating motor (7.5kw) has a current of 7A! ! ! The motor has serious quality problems. The manufacturer contacted and reissued 4 motors for replacement. They are currently being shipped... I don’t know if the manufacturer of such a high current has done no-load testing before leaving the factory. Such incidents occurred occasionally when the centrifuge arrived at the company for the first time this year. Since the workshop was in the commissioning stage at that time and the production load was very low, this phenomenon may not have been taken seriously. It was only after the production load increased later that the centrifuge was discovered to be unusable. Single test motor and centrifuge rotor belt are disconnected and check the centrifuge rotor bearing, there is no problem. Chemical Equipment and Machinery