INDUS-2 LCW plant control system using redundant PC at uppermost layer

INDUS-2 LCW plant is used for production, supply and cooling of Low Conductivity Water for heat removal from various components in INDUS-2 facility. Its control system has three layered architecture. There are VME based stations at lower most device and equipment interface layer and middle supervisory layer. The uppermost process control and GUI layer has PCs. To improve the system availability in case of process control PC failure, a redundant PC is used. This paper presents the scheme of automatic take over of full functionality by the redundant PC deployed in LCW plant control system. Two such schemes were successfully tested, one based on the parallel execution principle and another based on the principle of invoke on failure event (standby mode).