Steps for proper power shutdown and startup of DCS

Thread Content

The correct steps for shutting down and restarting the DCS are as follows: When it is necessary to perform maintenance on the DCS due to major repairs or other reasons, we often shut it down directly. However, such improper procedures can sometimes lead to serious consequences, such as the loss of configuration data and PID parameters. Therefore, it is necessary to carefully check the important parameters before and after a power outage and restart, ensuring careful and standardized operation. First step for proper power shutdown in DCS: Perform various checks before shutting down the power. 1. Open the door of the control station cabinet and check whether the cards are functioning properly and if there are any error indications ； 2. Monitor in real time from each operation station for any faults through fault diagnosis, and keep records of them ； 3. Check whether the power supply box is functioning properly, whether the power supply fan is operating, and whether the 5V and 24V indicator lights are working correctly; record the measured voltage values ； 4. Back up configuration files, PID parameters, drivers, and other important data required ； 5. Check the power supply redundancy, which includes AC power supply redundancy and DC power supply redundancy. AC power supply redundancy: By disconnecting one of the redundant AC ~220VAC supply lines, half of the system’s AC power supply circuits lose power, but the system should still be able to function normally. The redundant testing method for DC power supply is as follows: (1) First, disconnect the power to one of the power supply units, and measure the 5V and 24V voltages at the power terminals of the motherboard in each rack ； (2) First, supply power to one power supply unit, then disconnect the power to the other power supply unit, and then measure the 5V and 24V voltages at the power terminals of the motherboard in each chassis. The 5V output voltage of the power supply unit should be between 5.10V and 5.25V, while the 24V output voltage should be between 23.00V and 25.00V. If the voltage deviation is significant, it needs to be checked and addressed promptly; otherwise, it will affect the proper operation of the card. 6. Check the network cables and their layout: verify the continuity of the cables, ensure that the connections are secure, and replace any faulty cables promptly ； 7. UPS testing: Test the UPS battery’s power supply capacity by disconnecting the AC input to the UPS. UPS batteries should be discharged regularly, with a monthly discharge being recommended as a general guideline. The method of discharge involves disconnecting the UPS from its AC power supply and operating it on battery power until the batteries are nearly depleted. The above checks are primarily aimed at understanding the operating status of the system in advance, so that any abnormalities can be addressed promptly when the system is shut down. Step 2: Turn off the power in sequence. 1. After exiting the real-time monitoring and operating system from each control station, turn off the power to the industrial computer and monitor at that station ； 2. Turn off the power supply of each control station’s power supply box one by one ； 3. Turn off the power switches for each branch circuit ； 4. Turn off the UPS power switch ； 5. Turn off the main power switch. Step 3: Carry out DCS power-off maintenance. 1. Perform power-off purging and maintenance of the operation station and control station. This includes cleaning dust from inside the industrial computer, as well as components such as the control station chassis and power supply units ； 2. Perform maintenance on the faults identified before the power outage ； 3. Inspection of the system’s power supply lines. Including distribution boxes, terminal blocks, relays, safety barriers, etc. Ensure that all components are functioning properly and that the connections are reliable ； 4. Grounding system maintenance. This includes terminal inspection, grounding inspection of each operation station (industrial computer, monitor), grounding inspection of each control station (power supply, chassis), and ground resistance testing ； 5. Check the communication line connections and connection points to ensure that all components are functioning properly and that the lines are securely connected. Mark the dual network cables properly. Step 4 for proper power-up of DCS: After all on-site and DCS-related maintenance tasks are completed, check to confirm that the conditions for restarting the system are met. The person in charge of system protection shall confirm that all conditions are met before powering on the system. The process of powering on the system is as follows: 1. First, close the main circuit breaker in the distribution box, and check whether the output voltage is 220V±10% ； 2. Close the circuit breakers for each branch within the distribution box, and check the output voltage separately ； 3. If a UPS or voltage stabilizer is available, check whether the output voltage of the UPS or voltage stabilizer is normal. If it is not normal, identify the cause; only after it has been resolved can the subsequent steps of powering on the control station and the operation station be carried out. Step 5: Power on the control station; power on the DCS power supplies one by one. Step 6: Power on the operation station; power on devices such as its monitors and industrial computers. Step 7: Conduct checks to restart the DCS operation. 1. Open the control station cabinet door and check whether the cards are functioning properly and if there are any error indications ； 2. Monitor in real time from each operation station for any faults through fault diagnosis, which mainly includes alerts for card failures and communication issues ； 3. Check whether the power supply box is working properly, whether the power fan is operating, whether the 5V and 24V indicator lights are functioning correctly, and verify that the supply voltage is within the normal range ； 4. Check the network communication status of each layer, the operation status of the configuration, PID parameters, etc. Through the above maintenance overview, do you now have a deeper understanding of DCS power outages and power-ups? Power outage maintenance of DCS is an important part of its routine maintenance. It plays a crucial role in identifying potential faults within the system and extending its operational life. However, all of this requires strict, careful, and standardized procedures during maintenance, in order to achieve better results, avoid unnecessary losses, and ensure the stable operation of the system!