Production equipment shutdown issues
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During operation, two units suddenly stopped working; a interlock mechanism was activated, but there was no apparent reason for it. Both the electrical and instrumentation control cabinets showed normal readings with no alarms. The power supply circuits for these two units were different, as were their control cabinets. Has anyone encountered this situation? What could be the cause?
It may be that overcurrent caused by a grounded circuit (phase loss) led to the system shutting down. Check it out.
During the production process, various issues arise for which no cause can be found, or for which only a very small number of people know the reason; this happens in most companies. For cases of system shutdown like this, the person who posted the question should first have the electrical engineering team check the electrical records to find out what caused the shutdown I wonder if your electrical design has any records of being rejected or any backend records. Then investigate further based on this reason. If no issues can be detected electrically or in the instrument control system, it is still necessary to analyze whether there have been any sudden changes in the process parameters Check the historical trends of the DCS system.
Interlock malfunction is the cause; with careful investigation, it can definitely be identified
There are many reasons, and it is necessary to determine the fault based on the actual conditions on site.
Since it’s interlocking, the relevant interlocking events should be recorded, and these records are separate, with precision down to the millisecond level!
In the SIS interlock alarms, they occur simultaneously; however, in the DCS system, the devices whose operation is affected by the interlock stop first, while the devices that are the cause of the interlock stop later. Therefore, the cause of the interlock can be ruled out； There are no abnormal alarms from the electrical system or instruments.
Is the delay in cascaded settings the same for both the device that causes the interlock and the device that is the result of the interlock?
It’s probably a problem with the electrical interlock; we heard that noise several times without any obvious reason here before. After changing the sensor or some other component on the instrument, it stopped happening
Is it the fact that the operating voltage is higher than the supply voltage, which causes a sharp increase in voltage and leads to shutdown?
In the event of an emergency, first check the interlock system; the SIS system contains records of the incidents, providing detailed information on what caused the stoppage – whether it was due to the interlock or electrical issues, which makes it easy to analyze the situation.