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 LN2was 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 nonupgradability 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.