【Daily Question 20090217】Does DCS require no maintenance to operate properly during production?

No, it is necessary to strengthen the management of the control system rooms to meet the following requirements: (1) Personnel entering the rooms to carry out work must take measures to discharge static electricity, in order to eliminate the static electricity on their bodies. (II) The machine room environment must meet the requirements specified in the control system design. (III) Flammable, explosive, and toxic substances are strictly prohibited from being brought into the machine room; no miscellaneous items may be piled up inside, and no objects should be placed on the cabinets. (IV) The fire-fighting facilities in the machine room must be fully equipped. (5) The machine room should be equipped with rodent control measures to prevent rodent damage. (6) During the operation of the device, the use of mobile communication devices is prohibited in the control system room. Strengthen the management of spare parts for control systems to meet the following requirements: (1) There should be dedicated accounts and records for spare parts, so as to keep track of their inventory at all times; a sufficient quantity of spare parts should be maintained to ensure the stable operation of the control systems. (II) The environment in which the spare parts and components of the storage and control system are kept must meet the required storage conditions. (III) During the shutdown for maintenance of the equipment, power tests should be conducted on the spare parts to ensure they are in a ready state. To prevent virus infections, it is strictly prohibited to use unrelated software on the control system, as well as to perform any tasks that are not related to the configuration of the control system software. Isolation measures should be implemented between the control system and the information management system to prevent external computer viruses from attacking the control system. Strengthen the daily maintenance, fault handling, and inspection management of control systems. (1) The integrity and operational status of the host and peripheral hardware should be checked regularly on a daily basis. Ensure that the environmental conditions meet the requirements for the proper operation of the control system ； The power supply and grounding systems meet the standards ； Perform equipment cleaning at the prescribed intervals. (II) System software and application software must have dual backups, which should be kept safely ； The password for the control system or the key to the keypad lock should be kept by a designated person, and operations must be carried out strictly within the prescribed scope ； Software backups should include the software name, modification date, and person who made the changes, with relevant design modification documents archived. (III) If any abnormalities or faults are detected during system operation, maintenance personnel shall address them promptly, and record the symptoms of the fault, its causes, the methods used for resolution, and the outcomes. (IV) In principle, the major overhaul of the control system is carried out simultaneously with the major overhaul of the plant. During major repairs, a comprehensive and thorough cleaning of the system is required ； System debugging, diagnosis, maintenance, and calibration are to be carried out, as well as the verification of the interlock system ； During the major repair, the peripheral devices of the system also need to be inspected and tested. The maintenance of control systems shall be carried out in accordance with the requirements of the \"Code for Maintenance and Repair of Petrochemical Equipment\" (SHS 07008-2004). (5) It is necessary to strengthen the management of control system failures, formulate emergency response plans for such failures, and continuously improve the ability to handle unexpected issues.

1. Daily maintenance tasks 1.1 Process channel failures The most common type of failure in process channels is I/O card failures. The diagnosis and handling of such failures generally involve using system diagnostics, replacing the affected channel or using spare parts. As for damage caused by the aging of internal components or other reasons, it is usually difficult for thermal control personnel to determine the cause. The maintenance of I/O cards is generally handled by the manufacturer; currently, the capabilities of thermal control maintenance personnel are not sufficient to carry out such maintenance in the same way as with regular instruments. Moreover, I/O cards from manufacturers are trending toward being integrated, which means only spare parts can be purchased. Fortunately, such faults occur more frequently during the debugging phase, with a very low probability of appearing during normal operation. A failure in a primary component or control device sometimes cannot be detected directly by the operator; it is only after an anomaly or alarm occurs that the thermal control personnel are notified to handle it. This raises the requirements for the qualifications of maintenance and operational staff. Operational personnel need to provide detailed descriptions of the system’s conditions before and after a fault occurs, so that thermal control maintenance staff can address the issues quickly and accurately, thereby preventing the fault from worsening. Additionally, many DCS manufacturers promote the use of hot-swappable cards in their products; as operators, it is essential to take proper safety measures when replacing cards during operation, otherwise it could lead to changes in the system or in its load, especially with digital input cards. 1.2 There have been reports of freezes on the operator station for both domestic and imported equipment. The reasons for this are varied: hard drive or card failures, excessive load on the cooling fans, etc. Sometimes human error is to blame; such incidents often occur when modifying the control logic, installing software, restarting the equipment, or activating the equipment’s protection signals. In mild cases, this leads to abnormal operation of the equipment, while in severe cases it can result in shutdown of the equipment, with very serious consequences ； When restarting after a system crash, the startup time varies among different manufacturers – ranging from a few dozen seconds to several minutes. Faults caused by human error account for a large proportion of safety incidents in the field of thermal engineering; therefore, great attention is paid to such operations in order to reduce human-induced faults. 1.3 Abnormal operation of the ball marker is usually due to factors such as prolonged use of the mechanical components, aging, contamination, unreliable on/off switching, or loose cable connectors; in such cases, it is necessary to replace or inspect the relevant parts. 1.4 Control operation failure: This occurs when the control signals sent to the ball markers do not properly change the state of the process channels, resulting in failed operations. There are two possible causes for this: software defects on one hand, and hardware failures on the other. In such cases, it is usual to first check whether the functions of the process channels are working properly; if so, then check the control signals. If necessary, restart the system to initiate the operations again. 1.5 Regarding membrane keyboards, poor contact between the keys, loose signal cables, or improper operation by the main unit, as well as incomplete startup, can all lead to abnormal functioning. Different solutions should be applied depending on the specific situation. 1.6 A non-functional printer is usually due to configuration issues; such problems should be resolved by checking the printer’s settings and ensuring that its hardware is functioning properly. The weak functionality of reporting software is mainly manifested in system crashes caused by printers printing reports and SOE events, or when the SOE recording time on the printer does not match the actual situation ； After printing and viewing in SOE, it is not possible to return to the historical curve ； The chronological order of SOEs is inconsistent and can sometimes vary significantly, which delays the progress of accident analysis and may even lead to incorrect directions in such analysis. The SOE issue is related not only to unreasonable system design and the fact that SOE points are not all concentrated on a single DPU, but also to inadequate considerations in the design of the system’s hardware and software. It is believed that the occurrence of such faults is mainly due to imperfect consideration of the overall aspects of the power plant; insufficient attention to minor details leads to various faults. This situation requires serious attention, with every detail being examined carefully. It is necessary to work closely with the manufacturers to identify the problems and make further improvements, so that the system can serve production more effectively. 1.7 Power supply failures: There are many issues related to power supply failures, including improper fuse settings, the inability of backup power supplies to activate automatically, protection mechanisms that malfunction due to power fluctuations, and poor contact at connectors, all of which can lead to a lack of power supply. Dealing with power supply failures is relatively easy. First, carefully verify the configuration and capacity of the insurance to ensure it truly serves its purpose ； Secondly, it is important to have a UPS, as it ensures continuous power supply to the system even in case of power fluctuations; moreover, redundancy and backup options should be taken into consideration. 1.8 Failures caused by interference: The main sources of interference are grounding issues, the switching of backup power supplies, and high-power wireless communication devices such as mobile phones and walkie-talkies. Additionally, interference signals in the DCS system may be caused by the system itself. Therefore, the grounding issue in DCS systems is attracting increasing attention, especially in the power industry, where the startup and shutdown of high-power electrical equipment can interfere with the control signals of DCS systems, leading to unnecessary failures. To prevent interference signals from entering the system, it is necessary to strictly follow the requirements and methods for shielding and grounding, keep the signal wires away from sources of interference, and take measures to protect against power supply fluctuations. During the operation of the unit, manual switching between the master/slave process processors should be avoided as much as possible, unless it is absolutely necessary, in order to prevent disruptions. If switching is unavoidable, measures should be taken to switch control to manual mode first, so as not to affect the unit’s operating conditions. The use of high-power radio communication equipment is strictly prohibited in key areas such as between electronic devices and at the engineer stations. 2. Operation Management: The operation management of a DCS system involves the inspection of the system, the activation and deactivation of thermal protection systems, as well as the supervision and management of the DCS’s hardware and software. 2.1 Backup management of software: Application software (databases) should be backed up regularly, and even minor changes should be recorded ； Changes to the database must be saved to the engineer station as well as to a floppy disk or other hard drive. But be careful not to use the backup disk for an extended period to avoid data loss. 2.2 Software inspection and functional testing shall be carried out in accordance with the general methods for computer equipment, focusing mainly on the verification of permission settings at various levels: the use of non-DCS software is strictly prohibited; unauthorized personnel are strictly forbidden from performing configuration tasks. 2.3 The activation and deactivation of thermal protection systems must be carried out in strict accordance with the work order system. When maintaining a running device, proper isolation measures must be taken to prevent adverse reactions in related devices. To address these common faults and to prevent their occurrence as well as reduce their frequency, strict systems for inspection, maintenance, and regular checks should be established. It is necessary to fill out the DCS equipment inspection forms carefully, identify and address various minor defects promptly, thereby stopping faults in their infancy. Properly maintaining operation logs also helps to enhance management efforts.

I. Regulations on System Security Protection for PCs 1. Each PC must be equipped with a startup password, which should be changed regularly and recorded. 2. Different security levels of passwords for operators and engineers should be set separately for various human-machine interface systems. Engineer-level passwords must be changed regularly and the changes must be recorded. 3. No microcomputer operations shall be performed on servers that are in operation. 4. The engineer station can only be used by instrument DCS operators to perform various operations; no other personnel are allowed to use it. II. DCS Controller and PLC Section 1. The control programs contained within the DCS controller and PLC are not allowed to be modified or downloaded arbitrarily. 2. Any modifications to the control program must be approved by the equipment manufacturer and the instrument factory, and a formal notice must be issued before such modifications can be carried out. III. Environmental hygiene regulations for DCS and PLC control rooms. 1. The DCS control room must be maintained in a dust-free environment at a constant temperature of 25°C on a long-term basis. 2. Unauthorized personnel are strictly prohibited from entering the DCS control room. 3. DCS personnel must change their slippers upon entry. 4. It is strictly prohibited to park any types of equipment or miscellaneous items unrelated to this control room within the DCS control room. 5. DCS personnel must inspect the cleanliness of the control room daily, and any dirt or debris found must be dealt with immediately. 6. It is strictly prohibited to do anything unrelated to production in the DCS control room. 7. Take advantage of the downtime during major, medium, and minor repairs to clean the dust from PC, PLC, and DCS controllers, and check whether they are in normal operation after completion. IV. Regulations for the maintenance of DCS equipment. 1. When performing maintenance on DCS devices such as controllers and I/O module microcomputers, it is necessary to fully discharge human body static electricity. 2. Regularly check that the grounding systems of each DCS system are in normal condition. 　3. Detailed records must be kept for the maintenance of all types of DCS equipment. As well as the cause of the failure, solutions, results, and inspection outcomes. 4. The UPS power supply must be regularly checked to ensure it remains in good working condition. 5. The UPS batteries should be checked every six months to determine if any individual batteries have leakage issues. V. Regulations for DCS personnel inspections. 1. Regular inspections must be carried out on a daily basis at fixed times. Proactively ask the operators whether each control station is functioning properly. 2. Ensure that the environment inside the DCS control room meets the standards of dust-free and constant temperature. 3. Regularly create backups of historical station data (every three months) to free up hard drive space. 4. Check that all DCS expansion devices are in normal operating condition. 5. Detailed records must be kept after making any modifications to the system. This includes the modification notice, the modification process, whether the results are normal, and the person who made the modifications.

No. The term for a distributed control system in English is DCS; it is the result of the development of computer technology and automation technology. The capacity of power units is continuously increasing, and their parameters are constantly improving, creating vast opportunities for the application of DCS ； With the widespread use of DCS systems, it provides strong support for the safe and economical operation of power units. The control method of a power unit comprehensively reflects the level of automation. In the early days, due to low levels of thermal automation and low skill levels among the personnel, a decentralized, on-site operation approach was used, with monitoring and control functions located at the site itself. This control method was only suitable for units with low parameters and small capacity; it involved high labor intensity and poor safety standards. After the mid-1950s, the stage of development toward local control was reached; due to the widespread use of a master control system for the units, local centralized control methods for boilers, steam turbines, and feedwater deaeration were adopted accordingly ； In the 1960s, computer technology was applied to the monitoring and control of thermal power plants, leading to centralized control of the machinery, boilers, and electrical systems ； Programmable Control Filling (PLC) was developed in the early 1970s ； In the 1980s, with the development of advanced technologies such as control technology, computer technology, communication technology, and CRT technology, microcomputer-based distributed control systems (DCS) were developed abroad and gradually applied in thermal power plants ； In the 1990s, thanks to the development of microprocessors and Very Large Scale Integration (VLSI) technology, DCS evolved along with advances in computer technology, fault-tolerance techniques, human-computer interaction technologies, windowing technologies, and interactive graphics. Additionally, the development of standardized data communication networks and artificial intelligence contributed to the advancement of DCS toward more integrated and open systems. The widespread use of DCS in China’s power, petrochemical, food, and other industries. It features strong versatility, flexible system configuration, comprehensive control functions, easy data processing, centralized display and operation, a user-friendly interface, simple and standardized installation, convenient debugging, and reliable operation. With the development of China’s power industry, DCS has become a widely used device, with its application becoming increasingly widespread across both large-scale power units and smaller heating units. Consequently, the daily maintenance of such equipment also requires thermal control personnel to change their traditional way of thinking in order to meet the demands of modern development. The following is an explanation of the production and maintenance experience gained over the past few years: 1. Daily maintenance tasks 1.1 Faults in the process channels. The most common type of fault in these channels is that of the I/O cards. For such faults, diagnosis is carried out through the system, and the solution involves replacing the affected channel or using spare parts. As for damage caused by aging of internal components or other reasons, it is generally difficult for thermal control technicians to determine the cause. The maintenance of I/O cards is generally handled by the manufacturer; currently, the capabilities of thermal control maintenance personnel are not sufficient to carry out such maintenance in the same way as with regular instruments. Moreover, I/O cards from manufacturers are trending toward being integrated, which means only spare parts can be purchased. Fortunately, such faults occur more frequently during the debugging phase, with a very low probability of appearing during normal operation. A failure in a primary component or control device sometimes cannot be detected directly by the operator; it is only after an anomaly or alarm occurs that the thermal control personnel are notified to handle it. This raises the requirements for the qualifications of maintenance and operational staff. Operational personnel need to provide detailed descriptions of the system’s conditions before and after a fault occurs, so that thermal control maintenance staff can address the issues quickly and accurately, thereby preventing the fault from worsening. Additionally, many DCS manufacturers promote the use of hot-swappable cards in their products; as operators, it is essential to take proper safety measures when replacing cards during operation, otherwise it could lead to changes in the system or in its load, especially with digital input cards. 1.2 There have been reports of freezes on the operator station for both domestic and imported equipment. The reasons for this are varied: hard drive or card failures, excessive load on the cooling fans, etc. Sometimes human error is to blame; such incidents often occur when modifying the control logic, installing software, restarting the equipment, or activating the equipment’s protection signals. In mild cases, this leads to abnormal operation of the equipment, while in severe cases it can result in shutdown of the equipment, with very serious consequences ； When restarting after a system crash, the startup time varies among different manufacturers – ranging from a few dozen seconds to several minutes. Faults caused by human error account for a large proportion of safety incidents in the field of thermal engineering; therefore, great attention is paid to such operations in order to reduce human-induced faults. 1.3 Abnormal operation of the ball marker is usually due to factors such as prolonged use of the mechanical components, aging, contamination, unreliable on/off switching, or loose cable connectors; in such cases, it is necessary to replace or inspect the relevant parts. 1.4 Control operation failure: This occurs when the control signals sent to the ball markers do not properly change the state of the process channels, resulting in failed operations. There are two possible causes for this: software defects on one hand, and hardware failures on the other. In such cases, it is usual to first check whether the functions of the process channels are working properly; if so, then check the control signals. If necessary, restart the system to initiate the operations again. 1.5 Regarding membrane keyboards, poor contact between the keys, loose signal cables, or improper operation by the main unit, as well as incomplete startup, can all lead to abnormal functioning. Different solutions should be applied depending on the specific situation. 1.6 A non-functional printer is usually due to configuration issues; such problems should be resolved by checking the printer’s settings and ensuring that its hardware is functioning properly. The weak functionality of reporting software is mainly manifested in system crashes caused by printers printing reports and SOE events, or when the SOE recording time on the printer does not match the actual situation ； After printing and viewing in SOE, it is not possible to return to the historical curve ； The chronological order of SOEs is inconsistent and can sometimes vary significantly, which delays the progress of accident analysis and may even lead to incorrect directions in such analysis. The SOE issue is related not only to unreasonable system design and the fact that SOE points are not all concentrated on a single DPU, but also to inadequate considerations in the design of the system’s hardware and software. It is believed that the occurrence of such faults is mainly due to imperfect consideration of the overall aspects of the power plant; insufficient attention to minor details leads to various faults. This situation requires serious attention, with every detail being examined carefully. It is necessary to work closely with the manufacturers to identify the problems and make further improvements, so that the system can serve production more effectively. 1.7 Power supply failures: There are many issues related to power supply failures, including improper fuse settings, the inability of backup power supplies to activate automatically, protection mechanisms that malfunction due to power fluctuations, and poor contact at connectors, all of which can lead to a lack of power supply. Dealing with power supply failures is relatively easy. First, carefully verify the configuration and capacity of the insurance to ensure it truly serves its purpose ； Secondly, it is important to have a UPS, as it ensures continuous power supply to the system even in case of power fluctuations; moreover, redundancy and backup options should be taken into consideration. 1.8 Failures caused by interference: The main sources of interference are grounding issues, the switching of backup power supplies, and high-power wireless communication devices such as mobile phones and walkie-talkies. Additionally, interference signals in the DCS system may be caused by the system itself. Therefore, the grounding issue in DCS systems is attracting increasing attention, especially in the power industry, where the startup and shutdown of high-power electrical equipment can interfere with the control signals of DCS systems, leading to unnecessary failures. To prevent interference signals from entering the system, it is necessary to strictly follow the requirements and methods for shielding and grounding, keep the signal wires away from sources of interference, and take measures to protect against power supply fluctuations. During the operation of the unit, manual switching between the master/slave process processors should be avoided as much as possible, unless it is absolutely necessary, in order to prevent disruptions. If switching is unavoidable, measures should be taken to switch control to manual mode first, so as not to affect the unit’s operating conditions. The use of high-power radio communication equipment is strictly prohibited in key areas such as between electronic devices and at the engineer stations. 2. Operation Management: The operation management of a DCS system involves the inspection of the system, the activation and deactivation of thermal protection systems, as well as the supervision and management of the DCS’s hardware and software. 2.1 Backup management of software: Application software (databases) should be backed up regularly, and even minor changes should be recorded ； Changes to the database must be saved to the engineer station as well as to a floppy disk or other hard drive. But be careful not to use the backup disk for an extended period to avoid data loss. 2.2 Software inspection and functional testing shall be carried out in accordance with the general methods for computer equipment, focusing mainly on the verification of permission settings at various levels: the use of non-DCS software is strictly prohibited; unauthorized personnel are strictly forbidden from performing configuration tasks. 2.3 The activation and deactivation of thermal protection systems must be carried out in strict accordance with the work order system. When maintaining a running device, proper isolation measures must be taken to prevent adverse reactions in related devices. To address these common faults and to prevent their occurrence as well as reduce their frequency, strict systems for inspection, maintenance, and regular checks should be established. It is necessary to fill out the DCS equipment inspection forms carefully, identify and address various minor defects promptly, thereby stopping faults in their infancy. Properly maintaining operation logs also helps to enhance management efforts.

No. It is also necessary to regularly delete some of the unnecessary files, so as to prevent them from taking up hard drive space and affecting the machine’s performance. In addition, the historical records of some important operational parameters should be archived and copied to a tape drive as documentation.

The daily maintenance tasks specified by our company are as follows: 4.1 Inspections shall be carried out once a day, and the inspection records must be filled out carefully. The items to be checked include: 4.1.1 The environmental temperature and humidity in the cabinet rooms must meet the requirements specified in points 3.1.3 and 3.1.4, and the air conditioning systems must be operating properly； 4.1.2 Check the temperature inside the cabinet; it should be below 35°C during normal operation ； 4.1.3 Cleaning and condition of the control unit and cabinet filters ； 4.1.4 The fan at the top of the control cabinet should operate properly without any abnormal noises ； 4.1.5 The UPS is operating normally, with no alarms; the load rate remains unchanged compared to the previous day ； 4.1.6 The module should be in an online state, with the RDY and COM lights always on ； 4.1.7 The two main control units or servers that serve as redundancy should be in a master-slave configuration ； 4.1.8 The operator station and engineer station are operating normally, with no crashes or screen glitches ； 4.1.9 Check for any abnormalities in the history records ； 4.1.10 Ask the operators about the system’s operating status.

No. What system doesn’t require maintenance?

Daily maintenance tasks: The most common type of fault in the process channels is I/O card failures. For such failures, the usual approach involves using system diagnostics to determine the issue and then replacing either the channel or the faulty component. As for damage caused by aging of internal components or other reasons, it is generally difficult for thermal control technicians to diagnose such issues. The maintenance of I/O cards is generally handled by the manufacturer; currently, the skills of thermal control maintenance personnel are not sufficient to carry out such maintenance in the same way as for conventional instruments. Moreover, I/O card modules from manufacturers are trending toward being integrated, which means only spare parts can be purchased. Fortunately, such faults occur more frequently during the debugging phase, with a very low probability of appearing during normal operation. A failure in a primary component or control device sometimes cannot be detected directly by the operator; it is only after an anomaly or alarm occurs that the thermal control personnel are notified to handle it. This requires higher standards for the qualifications of maintenance and operation staff; the operation staff need to provide detailed descriptions of the conditions before and after a fault occurs, so that thermal control maintenance personnel can act quickly. Defects should be handled accurately to prevent the escalation of faults. In addition, many DCS manufacturers promote hot-swapping of cards in their product offerings. As operators, it is essential to take proper safety measures when replacing cards during operation; otherwise, it may lead to changes in the system or in its load, especially with digital I/O cards. There have been reports of freezes on the operator station for both domestic and imported equipment. There are various reasons for this, such as hard drive or card failures, excessive load on the cooling fans, etc. Sometimes human error is to blame; such issues often occur when modifying the control logic, installing software, restarting the equipment, or activating protective signals on the equipment. In mild cases, this leads to abnormal operation of the equipment, while in severe cases it can result in shutdowns of the equipment, with very serious consequences ； When restarting after a system crash, the startup time varies among different manufacturers – ranging from a few dozen seconds to several minutes. Human-induced failures resulting from such operations account for a large proportion of safety incidents in the field of thermal engineering; therefore, great attention is paid to such operations in order to reduce human errors. The operation of the 3-ball marker is abnormal, usually due to prolonged use of the mechanical mechanism. Aging. Pollution. The on/off switching is unreliable. Issues such as loose cable connectors simply require replacement and inspection. 4. Control operation failure: This occurs because the control signals for the ball marker do not properly change the state of the process channel, resulting in failed operations. This is caused by two factors: software defects on the one hand, and hardware failures on the other. To address such defects, it is usual to first check that the function of the process channel is normal, and then examine the control signals; if necessary, restart the initial operations. 5. For membrane keyboards, poor keyboard contact, loose signal cables, or improper operation of the host unit as well as incomplete startup can all lead to abnormal functionality; appropriate measures should be taken depending on the specific situation. 6. A non-functional printer is usually due to configuration issues; such problems should be resolved by checking the printer’s settings and ensuring that its hardware is functioning properly. The weak functionality of reporting software is mainly manifested in system crashes caused by printers printing reports and SOE, or discrepancies between the SOE recording time on the printer and the actual situation ； After printing and viewing in SOE, it is not possible to return to the historical curve ； The chronological order of SOEs is inconsistent and can sometimes deviate significantly, which delays the progress of accident analysis and may even misdirect the analysis. SOE issues are related not only to unreasonable system design and the fact that SOE points are not all concentrated on a single DPU, but also to inadequate considerations in the system’s hardware and software design. It is believed that the occurrence of such faults is mainly due to imperfect consideration of the overall aspects of the power plant; insufficient attention to minor details leads to various faults. This situation requires serious attention, with every detail being examined carefully. It is necessary to work closely with the manufacturers to identify the problems and make further improvements, so that the system can serve production more effectively. 7 Power supply failure: There are many issues related to power supply failures; the fuses are not configured properly, the backup power supply does not switch on automatically, power fluctuations can cause premature activation of protection mechanisms, and poor contact at connectors can lead to a lack of power supply. Dealing with power supply failures is relatively easy. First, carefully verify the configuration and capacity of the insurance to ensure it truly serves its purpose ； Secondly, it is important to have a UPS, as it ensures continuous power supply to the system even in case of power fluctuations; moreover, redundancy and backup options should be taken into consideration. 8 Failures caused by interference: The main sources of interference are grounding issues, the switching of backup power supplies, and high-power wireless communication devices such as mobile phones. Intercoms, etc. Additionally, interference signals in the DCS system may be caused by the system itself. Therefore, the grounding issue in DCS systems is attracting increasing attention, especially in the power industry, where the startup and shutdown of high-power electrical equipment can interfere with the control signals of DCS systems, leading to unnecessary failures. To prevent interference signals from entering the system, it is necessary to strictly follow the requirements and methods for shielding and grounding, keep the signal wires away from sources of interference, and take measures to protect against power supply fluctuations. During the operation of the unit, manual switching between the primary/secondary process processors should be avoided as much as possible, unless it is absolutely necessary, in order to prevent disruptions. If switching is indeed required, measures should be taken to switch control to manual mode first, so as not to affect the unit’s operating conditions. Ask about electronic devices. In key areas such as the engineer’s station, the use of high-power radio communication equipment is strictly prohibited.

No~ Maintenance is definitely necessary. It serves to ensure better operation, more time without failures, and a reduction in the frequency of failures.

DCS system maintenance (1) Regularly check the power supply of the DCS system; for redundant power supply systems, periodic switching tests should be conducted. At the same time, regular switching tests should be conducted on the UPS power supply, and the batteries should be discharged and charged regularly as required. (2) Regularly check whether the network connectors and all connection wires are secure, as well as whether the wiring terminals inside the control cabinet are firm and reliable. (3) Regularly check whether the control unit, I/O modules, other modules, etc. are operating properly. (4) Regularly check whether the grounding is secure and test whether the grounding resistance meets the requirements. (5) Regularly check the workload of controllers, computers, etc., and pay attention to any increases. (6) Regularly check the MMI hard drive and delete fragmented files; historical files should be regularly archived and backed up on external devices. (7) Utilize the maintenance period of the unit to reset each DPU (Distributed Processing Unit) and MMI (Human-Machine Interface) in the DCS system, in order to eliminate the cumulative errors that occur over time due to the continuous operation of the computers. (8) For the interfaces between the DCS system and other systems (such as MIS – Computer Management Systems, SIS – Plant-Level Monitoring Information Systems, etc.), it is recommended to install virus firewalls at the gateway stations on the side of those other systems, and to update the virus databases regularly. At the same time, update the operating system patches in a timely manner to enhance the security of the system. (9) Regularly check whether the system fans are working properly and whether there are any blockages in the air ducts, to ensure the system can operate reliably over the long term. (10) During shutdowns for major or minor maintenance of the unit, it is necessary to check the charge level of the COMS battery in the DPU main board. When COMS data is lost due to a dead COMS battery, the COMS batteries on the motherboard should be replaced in their entirety. (11) Conduct regular inspections*, periodic checks, and routine cleaning to ensure that the operating environment of the DCS system remains clean.

No, it is necessary to strengthen the management of the control system rooms to meet the following requirements: (1) Personnel entering the rooms to carry out work must take measures to discharge static electricity, in order to eliminate the static electricity on their bodies. (II) The machine room environment must meet the requirements specified in the control system design. (III) Flammable, explosive, and toxic substances are strictly prohibited from being brought into the machine room; no miscellaneous items may be piled up inside, and no objects should be placed on the cabinets. (IV) The fire-fighting facilities in the machine room must be fully equipped. (5) The machine room should be equipped with rodent control measures to prevent rodent damage. (6) During the operation of the device, the use of mobile communication devices is prohibited in the control system room. Strengthen the management of spare parts for control systems to meet the following requirements: (1) There should be dedicated accounts and records for spare parts, so as to keep track of their inventory at all times; a sufficient quantity of spare parts should be maintained to ensure the stable operation of the control systems. (II) The environment in which the spare parts and components of the storage and control system are kept must meet the required storage conditions. (III) During the shutdown for maintenance of the equipment, power tests should be conducted on the spare parts to ensure they are in a ready state. To prevent virus infections, it is strictly prohibited to use unrelated software on the control system, as well as to perform any tasks that are not related to the configuration of the control system software. Isolation measures should be implemented between the control system and the information management system to prevent external computer viruses from attacking the control system. Strengthen the daily maintenance, fault handling, and inspection management of control systems. (1) The integrity and operational status of the host and peripheral hardware should be checked regularly on a daily basis. Ensure that the environmental conditions meet the requirements for the proper operation of the control system ； The power supply and grounding systems meet the standards ； Perform equipment cleaning at the prescribed intervals. (II) System software and application software must have dual backups, which should be kept safely ； The password for the control system or the key to the keypad lock should be kept by a designated person, and operations must be carried out strictly within the prescribed scope ； Software backups should include the software name, modification date, and person who made the changes, with relevant design modification documents archived. (III) If any abnormalities or faults are detected during system operation, maintenance personnel shall address them promptly, and record the symptoms of the fault, its causes, the methods used for resolution, and the outcomes. (IV) In principle, the major overhaul of the control system is carried out simultaneously with the major overhaul of the plant. During major repairs, a comprehensive and thorough cleaning of the system is required ； System debugging, diagnosis, maintenance, and calibration are to be carried out, as well as the verification of the interlock system ； During the major repair, the peripheral devices of the system also need to be inspected and tested. The maintenance of control systems shall be carried out in accordance with the requirements of the \"Code for Maintenance and Repair of Petrochemical Equipment\" (SHS 07008-2004). (5) It is necessary to strengthen the management of control system failures, formulate emergency response plans for such failures, and continuously improve the ability to handle unexpected issues.

No. 1. Avoid unnecessary files from taking up hard drive space, and delete such files. 2. The historical records need to be archived. 3. Perform fault handling and data operations as necessary

I checked some information, but I’m not sure if the answer is correct. It’s not correct. It is also necessary to regularly delete some of the unnecessary files, so as to prevent them from taking up hard drive space and affecting the machine’s performance. In addition, the historical records of some important operational parameters should be archived and copied to a tape drive as documentation.

No, the DCS requires maintenance to operate properly during production, because it has redundant functions; even though it is functioning normally, there may be issues with some of the redundant devices, and timely maintenance is necessary.

1. Daily maintenance tasks 1.1 Process channel failures The most common type of failure in process channels is I/O card failures. The diagnosis and handling of such failures generally involve using system diagnostics, replacing the affected channel or using spare parts. As for damage caused by the aging of internal components or other reasons, it is usually difficult for thermal control personnel to determine the cause. The maintenance of I/O cards is generally handled by the manufacturer; currently, the capabilities of thermal control maintenance personnel are not sufficient to carry out such maintenance in the same way as with regular instruments. Moreover, I/O cards from manufacturers are trending toward being integrated, which means only spare parts can be purchased. Fortunately, such faults occur more frequently during the debugging phase, with a very low probability of appearing during normal operation. A failure in a primary component or control device sometimes cannot be detected directly by the operator; it is only after an anomaly or alarm occurs that the thermal control personnel are notified to handle it. This raises the requirements for the qualifications of maintenance and operational staff. Operational personnel need to provide detailed descriptions of the system’s conditions before and after a fault occurs, so that thermal control maintenance staff can address the issues quickly and accurately, thereby preventing the fault from worsening. Additionally, many DCS manufacturers promote the use of hot-swappable cards in their products; as operators, it is essential to take proper safety measures when replacing cards during operation, otherwise it could lead to changes in the system or in its load, especially with digital input cards. 1.2 There have been reports of freezes on the operator station for both domestic and imported equipment. The reasons for this are varied: hard drive or card failures, excessive load on the cooling fans, etc. Sometimes human error is to blame; such incidents often occur when modifying the control logic, installing software, restarting the equipment, or activating the equipment’s protection signals. In mild cases, this leads to abnormal operation of the equipment, while in severe cases it can result in shutdown of the equipment, with very serious consequences ； When restarting after a system crash, the startup time varies among different manufacturers – ranging from a few dozen seconds to several minutes. Faults caused by human error account for a large proportion of safety incidents in the field of thermal engineering; therefore, great attention is paid to such operations in order to reduce human-induced faults. 1.3 Abnormal operation of the ball marker is usually due to factors such as prolonged use of the mechanical components, aging, contamination, unreliable on/off switching, or loose cable connectors; in such cases, it is necessary to replace or inspect the relevant parts. 1.4 Control operation failure: This occurs when the control signals sent to the ball markers do not properly change the state of the process channels, resulting in failed operations. There are two possible causes for this: software defects on one hand, and hardware failures on the other. In such cases, it is usual to first check whether the functions of the process channels are working properly; if so, then check the control signals. If necessary, restart the system to initiate the operations again. 1.5 Regarding membrane keyboards, poor contact between the keys, loose signal cables, or improper operation by the main unit, as well as incomplete startup, can all lead to abnormal functioning. Different solutions should be applied depending on the specific situation. 1.6 A non-functional printer is usually due to configuration issues; such problems should be resolved by checking the printer’s settings and ensuring that its hardware is functioning properly. The weak functionality of reporting software is mainly manifested in system crashes caused by printers printing reports and SOE events, or when the SOE recording time on the printer does not match the actual situation ； After printing and viewing in SOE, it is not possible to return to the historical curve ； The chronological order of SOEs is inconsistent and can sometimes vary significantly, which delays the progress of accident analysis and may even lead to incorrect directions in such analysis. The SOE issue is related not only to unreasonable system design and the fact that SOE points are not all concentrated on a single DPU, but also to inadequate considerations in the design of the system’s hardware and software. It is believed that the occurrence of such faults is mainly due to imperfect consideration of the overall aspects of the power plant; insufficient attention to minor details leads to various faults. This situation requires serious attention, with every detail being examined carefully. It is necessary to work closely with the manufacturers to identify the problems and make further improvements, so that the system can serve production more effectively. 1.7 Power supply failures: There are many issues related to power supply failures, including improper fuse settings, the inability of backup power supplies to activate automatically, protection mechanisms that malfunction due to power fluctuations, and poor contact at connectors, all of which can lead to a lack of power supply. Dealing with power supply failures is relatively easy. First, carefully verify the configuration and capacity of the insurance to ensure it truly serves its purpose ； Secondly, it is important to have a UPS, as it ensures continuous power supply to the system even in case of power fluctuations; moreover, redundancy and backup options should be taken into consideration. 1.8 Failures caused by interference: The main sources of interference are grounding issues, the switching of backup power supplies, and high-power wireless communication devices such as mobile phones and walkie-talkies. Additionally, interference signals in the DCS system may be caused by the system itself. Therefore, the grounding issue in DCS systems is attracting increasing attention, especially in the power industry, where the startup and shutdown of high-power electrical equipment can interfere with the control signals of DCS systems, leading to unnecessary failures. To prevent interference signals from entering the system, it is necessary to strictly follow the requirements and methods for shielding and grounding, keep the signal wires away from sources of interference, and take measures to protect against power supply fluctuations. During the operation of the unit, manual switching between the master/slave process processors should be avoided as much as possible, unless it is absolutely necessary, in order to prevent disruptions. If switching is unavoidable, measures should be taken to switch control to manual mode first, so as not to affect the unit’s operating conditions. The use of high-power radio communication equipment is strictly prohibited in key areas such as between electronic devices and at the engineer stations. 2. Operation Management: The operation management of a DCS system involves the inspection of the system, the activation and deactivation of thermal protection systems, as well as the supervision and management of the DCS’s hardware and software. 2.1 Backup management of software: Application software (databases) should be backed up regularly, and even minor changes should be recorded ； Changes to the database must be saved to the engineer station as well as to a floppy disk or other hard drive. But be careful not to use the backup disk for an extended period to avoid data loss. 2.2 Software inspection and functional testing shall be carried out in accordance with the general methods for computer equipment, focusing mainly on the verification of permission settings at various levels: the use of non-DCS software is strictly prohibited; unauthorized personnel are strictly forbidden from performing configuration tasks. 2.3 The activation and deactivation of thermal protection systems must be carried out in strict accordance with the work order system. When maintaining a running device, proper isolation measures must be taken to prevent adverse reactions in related devices. To address these common faults and to prevent their occurrence as well as reduce their frequency, strict systems for inspection, maintenance, and regular checks should be established. It is necessary to fill out the DCS equipment inspection forms carefully, identify and address various minor defects promptly, thereby stopping faults in their infancy. Properly maintaining operation logs also helps to enhance management efforts.

Daily maintenance 1. Control room management: The management of personnel and equipment in the control room should be strengthened. To ensure the system operates under proper conditions, please follow the following: 1) Seal all cable pass-throughs (holes) that may allow dust, moisture, rodents, or other harmful insects to enter ； 2) Ensure the stable operation of air conditioning equipment, keeping room temperature changes within +5°C/h, and prevent condensation on system equipment due to sudden changes in temperature and humidity ； 3) Avoid using radios or mobile communication devices in the control room to prevent the system from being disturbed by electromagnetic fields and radio frequencies. 2. Operation station hardware management 1) Operate in a civilized manner, take good care of the equipment, keep it clean, and protect it from dust and water ； 2) It is strictly prohibited to modify or disassemble the machine without permission ； 3) Appropriate force should be used when operating the keyboard and mouse; handle them gently to avoid scratches on the surface caused by sharp objects ； 4) Try to avoid interference from electromagnetic fields on the monitor; avoid moving industrial computers, monitors, etc. while they are in use, and be careful not to pull or damage the cables connecting the devices and the communication cables. 5) Precautions when using the monitor: 􀂾 The monitor should be kept away from heat sources, and ensure that its ventilation openings are not blocked by anything ； 􀂾 Before making or breaking the connection, please ensure that the computer’s power switch is in the “off” position. Neglecting this procedure may cause serious injury to people and damage to computer equipment ； 􀂾 The monitor must not be cleaned with alcohol or ammonia; if cleaning is necessary, use a wet sponge and turn off the power supply before cleaning. 6) When using an industrial computer, the following should be noted: 􀂾 It is strictly prohibited to connect, disconnect, or move the industrial computer while it is powered on. Carelessness in performing this operation may cause serious injury to personnel and damage to computer equipment ； 􀂾 The industrial computer should be connected to the system’s ground through the grounding screws on the metal chassis, in order to reduce interference ； 􀂾 The filter of the industrial computer should be cleaned regularly, usually every 4-5 days ； 􀂾 The small port located at the back of the Advantech industrial computer motherboard cannot be used directly to connect a keyboard or mouse; a special adapter is required, otherwise it may cause the system to crash ； 􀂾 Do not touch the 230/110V switch on the back of the chassis, otherwise it may damage the motherboard. 3. Operation station software management 1) The use of non-genuine Windows 2000/NT software is strictly prohibited (non-genuine Windows 2000/NT software refers to OEM versions included with the product and other pirated versions) ； 2) Operators are strictly prohibited from exiting real-time monitoring ； 3) Operators are strictly prohibited from arbitrarily modifying the configuration settings of the computer system, as well as from arbitrarily adding, deleting, or moving files and directories on the hard drive ； 4) System maintenance personnel should use external floppy disks or optical discs carefully to prevent virus intrusion ； 5) It is strictly prohibited to perform unnecessary multi-tasking on the real-time monitoring operation platform ； 6) System maintenance personnel should create backups of the control subdirectory files (configuration files, flowcharts, SC language files, etc.), as well as keep records of system data such as the PID parameters for each control loop and the forward/reverse action settings of the regulators ； 7) After making the necessary adjustments to the system parameters, system maintenance personnel should promptly keep proper records. 4. Operation station inspection 1) Check whether hardware such as the industrial computer, monitor, mouse, and keyboard are in good condition ； 2) Monitor in real time whether the operation is normal, including data refresh and whether mouse and keyboard operations on various functional interfaces are functioning properly ； 3) Check the fault diagnosis screen to see if there are any fault alerts. 5. Control Station Management 1) It is strictly prohibited to modify or disassemble system components without authorization ； 2) Do not pull the motor cage wiring ； 3) Do not pull the ground wire ； 4) Avoid pulling or damaging the power supply lines ； 5) Lock the cabinet door. 6. Control station inspection 1) Check whether the card is functioning properly and if there are any fault indications (FAIL light on) ； 2) Is the power supply box working properly? 7. Communication network management 1) Do not pull or damage the communication cables ； 2) After the system is powered on, the wiring connectors must not come into contact with conductive objects such as cabinets; redundant communication cables and connectors should also not be in contact with each other to prevent damage to the communication network card. 3) On-site equipment inspection and preventive maintenance: Preventive maintenance should be carried out once a year during major overhauls, in order to assess the system’s operating condition and eliminate potential faults. During the major repair, thorough maintenance of the DCS system should be carried out, including: 1. Power outage maintenance of the operation stations and control stations. Dust cleaning of components including the inside of the industrial computer, the control station chassis, and the power supply box. 2. Inspection of the system’s power supply lines. 3. Grounding system maintenance. This includes terminal inspection and ground resistance testing. 4. On-site equipment maintenance. For specific procedures, please refer to the relevant equipment manual. After the major repair, the person in charge of system maintenance must confirm that all conditions are met before powering on the system, and must strictly follow the power-on procedures. 1. Power-on steps for the operation station 1) The computer passes self-check ； 2) File management: Verify that the paths for the WINDOWS NT system software and JX-300X system software are correct ； 3) The remaining disk space has not changed significantly, and the disk surface test passed. 2. Power-on procedure for the control station 1) Check the output of the regulated power supply ； 2) Power on the power supply box sequentially for inspection ； 3) Machine cage power distribution inspection ； 4) Card self-check ； 5) Card redundancy testing, etc. Redundancy testing: Normal redundancy involves two cards serving as hot backups for each other; each can be switched to active mode to carry out proper data processing. Card redundancy test: By plugging and unplugging cards that serve as backups while the system is powered on, it checks whether the redundancy function works properly. Communication redundancy test: By disconnecting the communication line connectors while the system is in operation, it is checked whether the data refresh and operational outputs at the control station are correct. The specific steps are as follows: ⑴ Disconnect the 2# communication line and keep the 1# communication line intact; use the download configuration function to test whether everything is working properly. If it works, it indicates that the 1# communication network is functioning normally. ⑵ Disconnect communication line #1 and keep communication line #2 intact; use the download configuration function to test whether everything is working properly. If it works, it indicates that the communication network connected to line #2 is functional. 3. Redesign and commissioning of parameters for the conventional control loop. The parameters of a conventional loop include the PID parameters of the controller and the forward/reverse action settings of the loop. Here, P represents the strength of the proportional action; the lower the value of P, the stronger the proportional action of the controller. Proportional action is a fundamental control mechanism necessary in any control scheme, and unless in some very special cases, users generally need to set the P parameter for proportional action ； I represents the integration time for the integral action; the smaller the value of I, the stronger the integral effect. The purpose of the integral action is to eliminate the discrepancy between the measured value and the setpoint in the control loop; as long as this discrepancy exists, the controller will actuate the control valve until the discrepancy becomes zero. Integration can improve control accuracy, but it reduces the stability of the loop ； D represents the differential time of the differential action; the larger the value of D, the stronger the differential action. The purpose of differential action is to provide early correction to the control of certain circuits that respond slowly to changes (such as temperature control circuits), thereby preventing large fluctuations and overshoot in the measured values. The best way to restart the control loops after a system shutdown is to keep a record of the PID parameters that have been successfully tuned for each loop, and re-enter them when restarting. Regarding the forward and reverse operation settings of the loop, there is no need to consider whether the control valve operates in an air-open or air-close mode during operation; the control valve should always be treated as an air-open valve. This is because the system has made the necessary adjustments during the configuration of the analog output points, and this is what distinguishes this system from other analog instruments and DCS systems. 4. Commissioning of complex circuits. Complex circuits refer to various control circuits other than conventional circuits. The commissioning of complex control loops should be determined based on specific circumstances; the basic principle is to start with the inner loop, then the outer loop, and finally add feedforward (taking three-shot control as an example).