[Weekly Accident Case Sharing] Accident Case 6: Power supply issues.

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I. Accident details: On April 7, 2014, two data switches in a company’s coking unit lost power simultaneously, causing all operator stations to go offline and severely disrupting the normal operations of the staff. II. Cause analysis: 1. Post-incident inspections revealed that the power for the two data switches in the company’s coking plant DCS control system was supplied solely by mains electricity, without the use of UPS power supply. 2. When maintenance personnel are working on a pump, electrical technicians cut off the power supply without first verifying the power lines. 3. The power connection labels in the distribution room are not clear. III. Identified problems: 1. The disadvantages of using mains power were not taken into account; the voltage from the mains is not stable enough, which can easily damage electronic devices. 2. There is insufficient awareness of the importance of power supply redundancy and hazard dispersion. The working power supplies for the operator station, engineer station, data server, and communication network should each be connected to the UPS or backup power supply via separate switching devices. 3. The markings during installation and debugging were unclear; the label on the power supply only read “mains power”. 4. The maintenance personnel did not follow proper procedures; they carried out repairs without confirming the situation properly. IV. Preventive measures: 1. Inspect all labels on the device; for those that are incomplete or unclear, use a calling code system to label them. 2. All operations and maintenance must be carried out strictly in accordance with the procedures. 3. Add a power switching device; the data switch shall be powered by redundant UPS units to eliminate power supply bottlenecks and improve system reliability.