Development of a measurement and control system for a 10 kW@20 K refrigerator based on Siemens PLC S7-300

Abstract

A 10 kW@20 K refrigerator has been established by the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. A measurement and control system based on Siemens PLC S7-300 for this 10 kW@20 K refrigerator is developed. According to the detailed measurement requirements, proper sensors and transmitters are adopted. Siemens S7-300 PLC CPU315-2 PN/DP operates as a master station. Two sets of ET200M DP remote expand I/O, one power meter, two compressors and one vacuum gauge operate as slave stations. Profibus-DP field communication and Modbus communication are used between the master station and the slave stations in this control system. The upper computer HMI (Human Machine Interface) is compiled using Siemens configuration software WinCC V7.0. The upper computer communicates with PLC by means of industrial Ethernet. After commissioning, this refrigerator has been operating with a 10 kW of cooling power at 20 K for more than 72 hours.