Problems and solutions encountered during debugging:
(1) The problem of module burning and its preventive measures.
During the debugging process, it is common to encounter situations where modules are burned out. There are many reasons for module burning, and the most important one is due to wiring errors, which can lead to external circuits causing strong electrical currents to enter.
Prevention and handling methods: Firstly, before testing the module, the external wiring of the module should be disconnected, and the power fuse of the module should be released before inserting the module and sending the power fuse. After the module testing is completed, the module must be pushed out; Secondly, before conducting the DCS and external equipment transmission experiment, it is necessary to check whether the wiring between the terminal cabinet and the external circuit is correct. During the inspection process, a multimeter should be used to check for backpin grounding and DC voltage to ensure that there is no strong electrical current entering. After there are no issues, insert the module for experimentation and push it out after completion. For example, after conducting transmission experiments on all equipment on the return module, the module can only be placed in the insertion position. Thirdly, try not to insert or remove modules with electricity, and do not insert modules that have not undergone transmission or system debugging into their positions. Strengthen the coordination of debugging work and avoid cross operation of the same system.
(2) Screen problems and solutions.
When a red bar appears on the configuration screen, it is generally caused by a closed circuit, which may be due to wiring errors or card failures, or it may be caused by a malfunction in the on-site instrument. If there are green bars appearing on the configuration screen, the configuration error may be due to duplicate or non-existent channels; When the data is displayed normally during debugging, but in production, the data is zero. In this case, the check is to see if there is a fault alarm in the data. If it is a red fault alarm, the operation of the card should be checked immediately; When multiple data in the monitoring screen fluctuate significantly at the same time, it is necessary to determine whether the fluctuation data is related to the production process parameters. If there are relevant parameters, it is necessary to notify professionals to check whether there is a change in the parameters due to fluctuations in a certain adjustment system. At the same time, the relevant adjustments should be put into manual mode, and on-site adjustments are necessary.
(3) Electromagnetic interference issues have occurred.
During the debugging process, it was found that there was a voltage rise at the common end of the DCS terminal cabinet, causing some equipment to malfunction. At the same time, it was found that the feedback signals of some baffles frequently changed, leading to frequent action of the induced draft baffle, which in turn caused overheating of the actuator motor, seriously affecting the adjustment quality of the automatic control system. The above is mainly caused by the interference of electrical signals on feedback signals, especially when it comes to equipment renovation in old factories. Mainly because the cable of the induced draft fan and the feedback signal cable of the induced draft fan baffle are in the same cable trench, the high-voltage cable generates a large amount of strong electrical interference.
Solution: Place a layer of steel wire mesh around the walls of the control room and connect it to the electrical protection PE grounding system to prevent strong electromagnetic field interference caused by the distance between high-voltage cables. Alternatively, place two types of cables in separate cable trenches to eliminate interference. Furthermore, a filtering circuit is installed on the DCS side of the feedback signal to solve this problem.
Problems and solutions encountered during operation
(1) The computer crashes during the operation of the DCS system.
One reason is that after debugging the DCS system, a system crash occurred, mainly due to a large number of modifications made during the debugging process, resulting in a large amount of garbage in the computer system. Secondly, the unreasonable allocation of functional areas in the computer caused excessive operating load. Solution: Try not to modify the configuration during the operation of the unit. If it is necessary to modify the configuration due to production needs, there should be a record of the modification. After the modification is completed, a large amount of system garbage before the modification should be cleaned up. During the operation of the computer TXP system, there are often some caches or generated junk files that require regular and scheduled cleaning by professionals to ensure the normal operation of the system; The second issue is that there is a crash during normal operation. To check if the monitoring screen data has been refreshed, check if the system alarm indicator light is normal. If it is normal, it is a problem with the operation of the DCS system.
Solution: Remote operation can be used to restart. It is not recommended to turn off the power unless absolutely necessary, and forced shutdown should be performed. Otherwise, it is necessary to perform a file self check after restarting. At this point, it is also necessary to check if other DCS systems are functioning properly. If the data remains unchanged, it indicates a malfunction in the system communication network. The operation of the network equipment should be checked immediately. If the hardware is working properly, it means that the communication protocol has malfunctioned and needs to be repaired through communication protocol self diagnosis and repair tools to solve the problem and restore normal operation.
(2) The DCS control system has hardware and software failures during operation.
The main reason for hardware problems during the operation of the DCS system is the failure caused by module damage. This type of malfunction is generally more obvious and the impact is also localized. Hardware failures during DCS system operation are mainly caused by improper or prolonged use, as well as aging of components within the module. If the dust, temperature, and humidity in the surrounding environment of the module exceed the standard, it will shorten the service life of the module. Therefore, the DCS control system has strict requirements for temperature, humidity, and cleanliness. So, before installing the DCS system, the control room should be fully decorated, and the air conditioning should be activated in a timely manner in summer. Especially, the cable holes must be sealed properly, otherwise, if the pipeline leaks and enters the cabinet, it may cause major faults;
The second is that the software of the DCS control system has malfunctioned. Caused by errors in the DCS control system software itself. Due to the complexity and heavy workload of DCS application software programs, it is difficult to avoid errors in the application software. Software failures are usually carefully debugged during the DCS debugging phase. If software problems are found, they should be reinstalled and repaired in a timely manner to solve the problem. After the system runs normally, software problems rarely occur.