Fault Diagnosis and Analysis of Analog Module in a Nuclear Power Plant

The model of analog input module of a nuclear power plant is SM336; F-AI 6 × 0/4-20mA Hart. The module is a standardized fault safety product of Siemens company. It is passivated in the application of T2000 control system. The vacuum pressure of the condenser, the speed of the steam turbine, the main steam pressure and other measured signals instantly become the minimum value, the fault indicator light (SF / safe) on the module is on, but after hot plugging, the instrument returns to normal display. Through fault information diagnosis and analysis, the fault cause of the analog input module is determined to be communication failure, and then the root cause of the fault is found through microscopic observation and control system simulation experiment. Finally, it is found that there is solder residue between the pins of the module address dial switch, which leads to the identification error when periodically scanning the address and causes the module passivation. The simulation experiment proves that the conclusion is correct.