Up-graded control system of liquid nitrogen management system of SST-1

Liquid Nitrogen (LN₂) is used for 80 K thermal shield of Steady-state Super-conducting Tokamak (SST-1), Integrated Fluid Distribution and Control System, Current Feeder System and 80 K refrigerant in Helium Liquefier/Refrigerator. A dedicated storage and distribution system for LN₂ was installed at IPR. The present system includes 3-nos of storage tanks, sub-cooler dewar, vacuum jacketed cryo-lines and instrumentation. This system employs PLC based supervisory control system with smart process instrumentation. Considering non- upgradability and lack of reliability due to obsolesce of components of automation system and future plan of 80 K single phase distribution system for thermal shield of SST-1, new control system is required. Various control schemes are employed for sub-cooler dewar, evaporators and storage tanks. The up-graded control system will offer ease of operation with improved automation, better maintainability and reliability. This paper describes design and development of up-graded control system of LN₂ system.