Learn in Three Minutes: Common Troubleshooting Measures for High-Speed Refrigerated Centrifuges

　　 High-speed refrigerated centrifuge Since its introduction, the centrifuge has undergone transformations from low-speed to adjustable-speed and then to high-speed models. Its progress has primarily been reflected in two key areas: centrifugal equipment and centrifugal technology—these two aspects complement each other closely. In terms of rotational speed, tabletop centrifuges generally fall into the categories of both low-speed and high-speed centrifuges, thus inheriting the technical characteristics of both types. The structure of a typical tabletop centrifuge consists of several main components: the motor drive system, the refrigeration system, the mechanical system, the rotor, and the system control unit. The development of universal tabletop centrifuges has blurred the distinction between low-speed and high-speed centrifuges. With a wide variety of rotors available, these centrifuges offer researchers an exceptionally broad range of applications, making them an ideal choice for scientific research laboratories.
　　What should you do if a high-speed refrigerated centrifuge encounters a problem? Generally speaking, what are the common issues, and how should they be addressed? Let’s hear the advice from laboratory centrifuge experts:
　　Since there is no relevant maintenance documentation or specialized repair tools available, we cannot confirm whether there is a problem with the motor’s control system. Therefore, we first inspected the rotor’s motor section. Using a multimeter, we confirmed that the motor’s electrical circuit is functioning properly—that is, there are no issues with the motor’s windings. Next, we examined the motor’s carbon brushes. After removing the carbon brushes from their bases on the rotor, we found no signs of common faults such as brush wear or unevenness. Thus, we can essentially rule out any problems with the rotor’s motor hardware (the hardware is in good condition). Consequently, the root cause of the malfunction can be largely attributed to an issue with the motor’s control system. However, given the lack of necessary documentation and tools, we’ve been unable to quickly identify and resolve the problem, leaving our equipment unable to operate normally.
　　Fault phenomenon: When the power to the centrifuge is turned on and the start button is pressed, the centrifuge fails to start and run. For a high-speed refrigerated centrifuge undergoing analysis and repair: After turning on the power to the centrifuge and pressing the start button, the rotor fails to rotate; however, the centrifuge’s compressor operates normally and provides cooling. Therefore, the fault analysis primarily focuses on the rotor’s motor and its control system.
　　High-speed refrigerated centrifuges must also be equipped with effective armored protection to prevent fragments from flying out in the event of rotor breakage.
　　1. Centrifugal chamber
　　The centrifuge chamber is where the rotor operates at high speed. It consists of two concentric steel cylinders. The inner cylinder is made of corrosion-resistant steel to prevent corrosion from spilled sample liquids. The outer cylinder is armored with a steel plate approximately 10 mm thick. Between the two cylinders runs an evaporative pipe that provides cooling for the centrifuge chamber.
　　2. Drive System
　　The drive systems of ultracentrifuges typically consist of water-cooled or air-cooled electric motors that transmit power to the rotor via precision gearboxes for speed variation, or through belt drives. Some systems also employ variable-frequency motors connected directly to the rotor shaft to achieve speed control. The rotor speed is selected using a rheostat and a controller equipped with a tachometer. In addition, these centrifuges are fitted with overspeed protection systems designed to prevent rotor rupture or explosion in cases where the rotor speed exceeds its maximum rated speed.
　　3. Temperature Control
　　The temperature control within the centrifugal chamber is achieved through an infrared radiation sensor installed beneath the rotor, which directly and continuously monitors the rotor's temperature, thereby ensuring sensitive and accurate temperature regulation. The temperature control system consists of a refrigeration compressor, a condenser, a dryer filter, an expansion valve, and an evaporator tube, among other components.
　　After adopting microcomputer technology, software can replace the functions of hardware or accomplish tasks that are difficult for hardware to perform—such as programmed control of centrifuges and motor control. This not only greatly simplifies the hardware architecture but also makes multi-functionality and automation a practical reality. In general, the core of the microcomputer control system for high-speed refrigerated centrifuges is a single-chip microcomputer. The hardware system includes: an operator interface, a motor control interface, a temperature control interface, a safety protection and monitoring interface, and a system monitoring module. The operator interface manages the keyboard and display; to facilitate user operation and monitoring of running parameters, the operator interface should adhere to principles of simplicity, conciseness, logical structure, and clear visibility of parameters.