Emergency response plan for control system

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Emergency response plan for control systems: During the production process, faults may occur in the communication cables of DCS, SIS, and PLC systems, as well as in controllers or I/O cards. Failures of PC operation stations or system power supplies can also lead to partial or complete shutdown of the equipment. To minimize losses, instrumentation professionals should implement appropriate emergency response plans; the following example uses a DCS control system. 1. Causes of failure: The main reasons for failures in DCS control systems include communication interruptions in the communication cables, failures in controllers or I/O cards, and power supply issues in the control system. 2. Fault symptoms: After a DCS system failure, a red alarm will appear on the DCS monitoring screen, and the system status screen will indicate the location of the fault. In severe cases, this can lead to loss of control, resulting in the partial or complete shutdown of the equipment. 3. Responsibilities of personnel during the accident: Instrument supervisor: Responsible for organizing the instrument maintenance staff to go to the site for repairs, providing professional guidance and coordination, organizing the relevant team to analyze the cause of the accident, and reporting to the appropriate supervisors. Instrumentation team leader: Arrives at the scene as soon as possible to investigate the cause of the DCS system failure, prepare all the technical documents and DCS spare parts needed for repairs, and participate in the analysis of the cause of the incident. Instrument maintenance personnel: Assist process engineers in making adjustments on-site and in restoring normal operation of the control systems; work together with technical staff to carry out maintenance tasks on the DCS system. 4. Specific steps for action: 4.1 Once a DCS control system failure occurs or is reported, the person responsible must report it to the on-duty shift leader or workshop supervisor as quickly as possible. 4.2 Personnel responsible for responding to control system failures: there are two teams, namely the control room emergency team and the on-site emergency team. The team members should be aware that the on-site emergency response team is headed by the instrument supervisor, and its role is to work alongside the process engineers to make adjustments on site and address any issues with the instruments ； The emergency team in the control room is headed by the instrumentation supervisor and is primarily responsible for identifying faults in the DCS control system as well as handling those faults. 4.3 Instrument technicians must provide technical instructions to the personnel involved in the maintenance work regarding the precautions and challenges associated with the control system, so that everyone is aware of them. 4.4 Notify the production workshop to make preparations for production adjustments and shutdown. 4.5 Identify the cause of the fault. Since DCS systems have redundant control functions, with redundancies in power supplies, controllers, and I/O cards, once the cause and location of the fault are determined, the corresponding equipment should be replaced while the system is still powered on. It is necessary to wear anti-static wristbands during this process, and care must be taken to avoid exacerbating the fault and causing greater losses. 4.6 If a fault causes the unit to stop operating, work together with the process engineers to switch production to on-site control and adjust the control valves to bypass control; once the fault has been resolved, collaborate with the process engineers to switch back to DCS control. 4.7 After troubleshooting the control system issues, check whether the DCS control system is fully operational, and address any instrument faults promptly. 5. DCS System Failures and Recovery 5.1 Communication Network Failures: An alarm is generated in the event of an Ethernet network failure, but such a failure does not affect the system’s network communication. The DCS maintenance staff can check for network failures and restore service promptly. In the event of a network disconnection in the control network: 5.1.1 Notify the supervisor of production planning and technology department immediately. 5.1.2 Check the operation status of key process monitoring indicators and the operating condition of various valves through the direct control station. 5.1.3 The instrument technicians shall immediately work together with the workshop process engineers to take appropriate safety measures to prevent the accident from worsening. 5.1.4 The instrumentation technician should first check whether the redundant controller is operating properly. If the main controller fails and the backup controller does not switch over correctly, the technician must immediately inform the relevant supervisors and request that a manual switch-over of the controllers be carried out. In the event that the switch-over fails, the technician should inform the workshop supervisor to prepare for an emergency shutdown. 5.1.5 Once it is confirmed that the controller is functioning properly, promptly check whether the status of the switch and its power supply are normal, as well as the network connections between each redundant controller and the switch, and between the engineer station and operator station and the switch: verify if there are any damaged, loose, or disconnected RJ45 connectors; if the connectors are damaged, replace them with spares or fabricate new ones on-site, and tighten any loose connectors immediately. After that, use the engineer station to check the network to ensure it is operational and that normal operation can be resumed. 5.2 Controller or I/O card failure 5.2.1 Failure of the system’s redundant controller 5.2.1.1 Emergency procedure for controller desynchronization: Manually power down the backup controller and restart it to restore synchronization ； 5.2.1.2 Emergency procedure in case both redundant controllers fail simultaneously: First, determine which one is acting as the master controller at that moment, and immediately perform a manual switch between the master and slave controllers. If the switch does not succeed, report to the workshop supervisor promptly and wait for the order to stop the machine. 5.2.2 Emergency procedures for damaged I/O cards: 5.2.2.1 In the case of a damaged non-redundant AI/DI/DO card, a spare card can be inserted in place of the damaged one. It is necessary to work closely with the process team to promptly obtain the necessary repair tickets for replacement and to configure the system with a single-point setup. 5.2.2.2 If a redundant AO card is damaged, promptly issue the relevant maintenance tickets to replace it with a spare part; if this does not succeed, report to the relevant supervisors immediately and take measures to effect the replacement, awaiting instructions from the production workshop supervisor. 5.3 Operator Station (HIS) failure: 5.3.1 Notify the relevant instrumentation engineers to conduct inspections and repairs. 5.3.2 Check whether the operation station restarts properly. 5.3.3 The operation station can be started, but the operation interface will not start; check whether there is a fault with the card. 5.3.4 Check if there is a network failure. 5.4 Power outage of the DCS system 5.4.1 Notify the workshop and the Production Technology Department immediately. 5.4.2 Check the operation status of key monitoring indicators of the device. 5.4.3 The instrument technicians shall immediately work together with the workshop’s process team to take appropriate safety measures to prevent the accident from worsening. 5.4.4 Check whether the power supply for the DCS system meets the requirements (220VAC). Handling of abnormal UPS power supply: 5.4.4.1 If a fault occurs in the UPS main circuit and it does not switch automatically to bypass mode, contact the electrical team promptly and seek approval from the relevant supervisors to switch the UPS to \"manual bypass\" mode. 5.4.4.2 In the event of failures in the UPS main circuit, automatic bypass, manual bypass, or electrical power supply, it should automatically switch to DC battery power. During this power supply period, backup of the DCS configuration as well as backups of the systems on each industrial computer must be carried out immediately, while waiting for the command to shut down the plant. 5.4.4.3 If there are failures in the UPS main circuit, automatic bypass, manual bypass, and batteries, it is necessary to promptly inform the workshop supervisor and relevant managers so that they can prepare for an emergency shutdown. 5.4.4.4 If external interference affects the power supply to the DCS system, resulting in its inability to operate properly, the grounding condition should be checked first. If the grounding is normal but the interference cannot be eliminated immediately, it is necessary to report the situation to the relevant supervisors right away, and at the same time inform the workshop supervisor to shut down the system. 5.5 Once the power supply to the DCS system is normal, start the control station first. 5.6 After the control station is started, an operator station should first be started on the operator station group. Do not start other operation stations for now, as this will improve the startup speed of the entire DCS system. 5.7 Check the status of the DCS system. 5.8 Start other DCS operation stations. 6 Summary of emergency response plans for control systems. Through the drills related to emergency response plans, issues and shortcomings can be identified, allowing these plans to be improved as much as possible. It is necessary to consider all details so that a comprehensive response can be provided and problems can be resolved quickly in the event of an actual emergency. Those who participated in the drills should write down their reflections on them.