System for the automatic control of a cryogenic helium plant

The design and development of a digital system for the automatic control of a KGU-500/4.5 helium cryogenic plant are discussed. The plant regime includes a preliminary nitrogen refrigerator and two consecutive helium expansion cascades in compressed-gas motors. Design emphasis was paid to selecting the actuating electrical mechanisms, properly incorporating the control and data acquisition computers, unifying the electronic monitoring and control equipment, and selecting appropriate software for the control computer. A layout of the helium plant is shown and a flowsheet of the control program for the refrigeration unit is given. The system was tested for plant freezing and heating conditions to determine the overall integrity and compatibility of the unit.