Fault Masking Technique for Bowl Cleaning Automation Process using Digital Sensor Simulation Algorithm

Implementation of digital sensor simulation concept for bowl cleaning machine using STL algorithm is presented in this paper. STL algorithm has been generated using three variables and is incorporated in the execution logic of the PLC for the bowl cleaning process. Digital sensors like proximity sensors and limit switches establishes closed loop control system, which governs machine movements. In case of any digital sensor failure, the entire machine goes into hold mode with the propellant bowl being stuck with it. This hinders the failure diagnosis and rectification activities seriously due to safety concerns. Hence, an attempt has been made in this paper for retrieving the bowl cleaning machine to its home position safely in case of digital sensor failure. Thereby, enabling the shifting of propellant bowl to the standby machine. An equivalent simulation network for the proposed algorithm is designed using ladder logic and is analyzed by Karnaugh Map and Boolean algebra. Sum of product expression is derived and is validated by acquiring the status of digital input module for the corresponding channels in response to sensor simulation using S7-315 2PN/DP PLC and WINCC SCADA 7.4. Proposed network performance is validated by plotting the process trends in case of sensor failure scenario.