The level 3 fault display is set in the signal box of the central control room. When the equipment fails, the signal box will prompt the staff with sound and light alarm to deal with the fault in time. When dealing with faults, the faults are classified. Some faults require the system to stop running, but some faults have little effect on the system work. The system can run with faults, and the faults can be eliminated during operation, thus greatly reducing the overall system stop. Run time to improve system reliability operation level. Input signal reliability study To improve the reliability of the signal input from the field, first select the transmitter with high reliability and various switches to prevent short-circuit, open circuit or poor contact of the transmission signal line for various reasons. Secondly, digital filtering program is added during programming to increase the credibility of the input signal. Add a timer after the input contact in the field. The timing is determined according to the contact jitter and the response speed of the system. Generally, it is several tens of ms. This ensures that the contact is stable and closed before other responses are available. Analog signal filtering can be used The programming method continuously samples the live analog signal, and the sampling interval is determined by the conversion speed and the rate of change of the analog signal. The sub-sampled data is stored in the data register respectively. When the last sampling is finished, the data comparison, the data exchange instruction, the data segment comparison instruction are used to remove the maximum and minimum values, and the intermediate value is retained as the sampling result is stored in the data register. Improving the reliability of the signal read into the field can also take advantage of the characteristics of the control system and use the relationship between the signals to determine the credibility of the signal. For liquid level control, since the size of the tank is known, the opening and pressure of the inlet or outlet valve are known, and the height of the liquid in the tank is known to be within a certain range of time. At this time, the data sent to the PLC by the liquid level gauge differs greatly from the estimated liquid level height. The judgment may be that the liquid level gauge is faulty, and the operator is notified by the fault alarm system to check the liquid level gauge. Another example is that each tank has upper and lower liquid level limit protection. When the switch is actuated, the signal is given. Whether the signal is authentic or not, we compare this signal with the tank level gauge signal during programming, if the level gauge reading is also The limit position indicates that the signal is true; if the level gauge reading is not at the limit position, it may be judged that the liquid level limit switch is faulty or the transmission signal line is faulty, and the operator is also notified by the alarm system to handle the fault. Since the above method is adopted in programming, the reliability of the input signal is greatly improved. 4. Performance study of the actuator When the signal from the site is accurately input to the PLC, the PLC executes the program and adjusts and controls the field device through the actuator. How to ensure that the executing agency works according to the control requirements. When the executing agency does not work as required, how to find the fault? We take the following measures: When the load is controlled by the contactor, starting or stopping such load turns to control the contactor coil, whether the contactor is reliably sucked at startup, and whether the contactor is reliably released when stopped, which is of concern to us. X0 is the contactor operating condition, Y0 is the control coil output, and X1 is the contactor auxiliary normally open contact that is led back to the PLC input. The timer timing is greater than the contactor action time. R0 is the set fault bit. When R0 is ON, it indicates that there is a fault, and the alarm is processed. When R0 is OFF, it indicates that there is no fault. Previous page next page Geosynthetic Clay Liner,Cl Landfill Liners,Bentonite Lake Mat Fiberglass Geogrid,PVC GeomembraneCo., Ltd. , http://www.chgeotextile.com
The level 2 fault display is set on the large-screen monitor in the central control room. When the device fails, there is a text display fault type, the corresponding device on the process flow diagram flashes, and the fault is recorded in the historical event table.