[Daily Question 20090323] In what aspects can the reliability and safety of distributed control systems be improved?

Reliability is mainly due to the following functions: Interlock protection function, self-diagnosis function, redundancy measures, manual control operation measures for system failures, etc. The key is also the reliability of the process structure of the hardware, the use of integrated circuits and surface mounting technology, etc.

(1) Due to the decentralized functions of the system, once a failure occurs at the management level or individual control levels, the threat to the overall situation is small and the reliability* * Increase. (2) The hardware (referring to electronic equipment) in the system all uses large-scale integrated circuits and other high-quality components, thus providing good conditions for improving the mean time between failures (MTBF) of the hardware part. (3) For critical parts, dual designs or redundant backups are often used to further enhance reliability. At the same time, most distribution systems adopt hierarchical backup measures. When the basic controller fails, for important regulatory loops, analog instruments are generally used as automatic backup, or the output can be directly manually operated through the operation panel to control switches, valves, etc. Some systems even use two sets of microcomputers in the basic controller. Once the main controller fails, it automatically switches to its backup controller. * * Improved system security. (4) The system has complete self-examination and self-diagnosis functions. Under the influence of the microcomputer, the diagnostic program is used to conduct regular diagnosis and maintenance of the system. If a fault is found, the fault will be displayed on the CRT and an alarm signal will be sent to attract the operator's attention. At the same time, the type and location of the faulty equipment can be identified through the display code on the CRT, so that maintenance personnel can quickly and accurately eliminate the fault, thus * * Reduced system mean time to repair (MTTR)

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Find comprehensive answers with relevant knowledge: The improvement of reliability and security of distributed control systems is reflected in the following aspects:: (1) Due to the decentralized functions of the system, once a failure occurs at the management level or individual control levels, the threat to the overall situation is small and the reliability * * Increase. (2) The hardware (referring to electronic equipment) in the system all uses large-scale integrated circuits and other high-quality components, thus providing good conditions for improving the mean time between failures (MTBF) of the hardware part. (3) For critical parts, dual designs or redundant backups are often used to further enhance reliability. At the same time, most distribution systems adopt hierarchical backup measures. When the basic controller fails, for important regulatory loops, analog instruments are generally used as automatic backup, or the output can be directly manually operated through the operation panel to control switches, valves, etc. Some systems even use two sets of microcomputers in the basic controller. Once the main controller fails, it automatically switches to its backup controller. * * Improved system security. (4) The system has complete self-examination and self-diagnosis functions. Under the influence of the microcomputer, the diagnostic program is used to conduct regular diagnosis and maintenance of the system. If a fault is found, the fault will be displayed on the CRT and an alarm signal will be sent to attract the operator's attention. At the same time, the type and location of the faulty equipment can be identified through the display code on the CRT, so that maintenance personnel can quickly and accurately eliminate the fault, thus * * Reduced system mean time to repair (MTTR)

Mainly redundant settings, interlocking functions, alarm settings, etc.

In what aspects can the reliability and safety of distributed control systems be improved? reliability: 1. Redundancy requirements: DCS operating stations, communication buses, etc. should be configured in redundant configurations, and 20% of the operating stations and communication buses should be guaranteed to be in reserve. ； I/O cards should have 10~15% spare capacity ； There should be 10% space for card installation in the cabinet and 10% spare terminal blocks. ； Redundant configuration principles: Important control loop 1: 1 ； Second important control loop n: 1 (n is the number of loops) For the input of important detection signals, the user can choose dual input cards. 2. Hardware quality requirements DCS mean time to failure (MTBF) and mean time to repair (MTTR) should be within the allowable range ； The accuracy of analog I/O cards should not be less than 0.1% ； Whenever possible, use DCSs that hold ISO9001 quality assurance certificates and have operational performance in the petrochemical industry. ； 3. Anti-interference performance DCS device should have the ability to resist the influence of radio frequency electromagnetic fields ； 4. System expansion should be able to expand multiple systems as needed without interrupting process operations. 5. System software maturity DCS system software should be standardized, modular, mature and reliable ； Configuration and operation are simple and flexible. Meeting these requirements can improve system reliability.

The improvement of reliability and security of distributed control systems is reflected in the following aspects:: 1. Whether the system is regularly backed up, mainly software backup: including operating system, driver, emergency boot disk (especially for WinNT system), control system software, Keycode disk (Centum authorized disk), control configuration database, and ensure that the control configuration data is up to date and complete. In view of the shortcomings of easy wear of optical disks and floppy disks in actual use, pay attention to making more backups, and use backup forms such as mobile hard disks, U disks, and hard disks to ensure the preservation of each software ； Hardware backup: Appropriate backups should be made based on the actual situation for components that are fragile and have short life cycles and key components such as keyboards and mice, I/O modules, power supplies, communication cards, etc. 2. The most important and critical thing is the maintenance of the DCS system. System maintenance mainly includes daily maintenance; preventive maintenance and fault maintenance. Daily maintenance and preventive maintenance are maintenance performed when the system does not malfunction. Fault maintenance occurs after a fault occurs, which often causes partial functional failure of the system and adversely affects production; on the contrary, preventive maintenance is to conduct planned regular maintenance of the system when the system is operating normally, to grasp the operating status of the system in a timely manner, eliminate hidden dangers of system faults, and ensure long-term stable and reliable operation of the system, forming the concept of regular maintenance. Practice has proven that regular maintenance can effectively prevent sudden DCS failures and generate considerable indirect economic benefits. I think that if you want to ensure the reliability and security of the distributed control system, you must start from the above two points. It is crucial to truly achieve regular system backup and system maintenance, because once the system has a fatal failure, the system backup can play a positive role, and system maintenance is to ensure the reliability and security of the distributed control system.

Find comprehensive answers with relevant knowledge: The improvement of reliability and security of distributed control systems is reflected in the following aspects:: (1) Due to the decentralized functions of the system, once a failure occurs at the management level or individual control levels, the threat to the overall situation is small and the reliability * * Increase. (2) The hardware (referring to electronic equipment) in the system all uses large-scale integrated circuits and other high-quality components, thus providing good conditions for improving the mean time between failures (MTBF) of the hardware part. (3) For critical parts, dual designs or redundant backups are often used to further enhance reliability. At the same time, most distribution systems adopt hierarchical backup measures. When the basic controller fails, for important regulatory loops, analog instruments are generally used as automatic backup, or the output can be directly manually operated through the operation panel to control switches, valves, etc. Some systems even use two sets of microcomputers in the basic controller. Once the main controller fails, it automatically switches to its backup controller. * * Improved system security. (4) The system has complete self-examination and self-diagnosis functions. Under the influence of the microcomputer, the diagnostic program is used to conduct regular diagnosis and maintenance of the system. If a fault is found, the fault will be displayed on the CRT and an alarm signal will be sent to attract the operator's attention. At the same time, the type and location of the faulty equipment can be identified through the display code on the CRT, so that maintenance personnel can quickly and accurately eliminate the fault, thus * * Reduced system mean time to repair (MTTR)

The so-called reliability and security, in addition to the hardware and software of the system that everyone knows (because these two are outside our control, unless we spend a lot of money), I think we should do the following: 1: Redundant, no more to say 2: Leave enough space for cabinets, chassis, cards, and points 3: Don't just listen to the manufacturer, add a pair of control cards based on the manufacturer's quotation. The best load on the control card is 30%. 4: It is best to have one mains power supply and one UPS for the system power supply. It is best for these two channels to be independent. It doesn't come from one transformer, but from two sources. 5: The 24VDC external power supply load must be calculated enough, it is better to have more than lack 6: To do a good job of grounding, be sure to measure the ground resistance. 7: Let the operators take good care of the system and not open too many windows for operation. 8: Regular maintenance. Hope to continue to add

(1) Due to the decentralized functions of the system, once a failure occurs at the management level or individual control levels, the threat to the overall situation is small and the reliability* * Increase. (2) The hardware (referring to electronic equipment) in the system all uses large-scale integrated circuits and other high-quality components, thus providing good conditions for improving the mean time between failures (MTBF) of the hardware part. (3) For critical parts, dual designs or redundant backups are often used to further enhance reliability. At the same time, most distribution systems adopt hierarchical backup measures. When the basic controller fails, for important regulatory loops, analog instruments are generally used as automatic backup, or the output can be directly manually operated through the operation panel to control switches, valves, etc. Some systems even use two sets of microcomputers in the basic controller. Once the main controller fails, it automatically switches to its backup controller. * * Improved system security. (4) The system has complete self-examination and self-diagnosis functions. Under the influence of the microcomputer, the diagnostic program is used to conduct regular diagnosis and maintenance of the system. If a fault is found, the fault will be displayed on the CRT and an alarm signal will be sent to attract the operator's attention. At the same time, the type and location of the faulty equipment can be identified through the display code on the CRT, so that maintenance personnel can quickly and accurately eliminate the fault, thus * * Reduced system mean time to repair