Research On Automatic Control Of Centrifuge’s Safe Operation

In the pharmaceutical industry, the centrifuge is usually used as the main solid-liquidseparation equipment in raw material drug production. In these explosive hazardous areas,the centrifuge’s safety, reliability and easy to maintain become increasingly important. Thecontrol circuit’s reliability is so poor that can’t meet the safety requirements. The projectstudy automatic control of the centrifuge. The frequency converter and the PLC controlmode are used, in order to improve the reliability of the control circuit and realize the safeoperation of the centrifuge.The working medium and operating conditions is different in each step of the processof the chemical and pharmaceutical industry, so the performance requirements vary inexplosion-proof, anticorrosion, high temperature and cleanliness. The centrifuge is therotating equipment, and the vibration, temperature, motor current, differential speed andthe oxygen content are the important factors to affect the safe operation of centrifuge.Based on the analysis of the centrifuge’s working principle, the key technology andoperational characteristics, the plan was determined to use frequency control to achievesmoothing start and variable speed.The multi-speed operation means was selected based on the process requirements andmaterials. The necessary description of the protection module was made, which includeoverload protection, over voltage protection, current protection, under-voltage protection,input phase loss protection, thermal protection, short circuit protection, ground shortcircuit protection, motor protection and braking resistor protection, etc.The detection means, such as motor temperature, oil level, bearing temperaturedetection, overload protection circuit, were improved. And the safety factor of thecentrifuge in the explosion-proof environment was improved effectively.