How to deal with accidental falling off a train
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After the main fan in our plant tripped, we checked various monitoring parameters, and none of them were out of limit. No records of jumping out of the vehicle were found either. The electrical high-voltage cabinet is also fault-free. It can operate normally after being restarted. I’m not sure if it’s interference; could the PLC module generate a signal on its own momentarily (indicating a fault)? Because this phenomenon has occurred several times, and the cause cannot be found. If the cause cannot be found, can the interference be suppressed? For example, by adding a time relay at the output side that triggers after 1 or 2 seconds. If there’s a possibility of interference, then it won’t be there. Is it possible to do this?
Count the signals that can cause a system shutdown; by checking which counters have values when the next shutdown occurs, it’s possible to identify the likely source of the problem. It’s feasible to use a delay mechanism. Since this is a critical piece of equipment, it’s best to determine the appropriate delay time through a meeting, with the decision documented in a minutes sheet and approved by all relevant parties.
Delaying it is possible, but it only provides a temporary solution; it can cause wear and damage to the equipment. For devices like this, it is still necessary to analyze the source of the fault.
By adding these signals to the SOE records, when a trip event occurs, the SOE will help you locate the control point information that had the greatest impact on that trip event
Poster: It’s best to first figure out what causes the system to shut down abruptly, as there are only a few possible reasons for this. These reasons aren’t recorded in the shutdown logs; it has something to do with the scanning frequency of the PLC. If the PLC’s scanning cycle is 1 second, while the shutdown occurs in just a few milliseconds, then no record will be available on the upper-level computer. It would be better to write a program in the PLC that keeps track of faults, so that the cause of the shutdown can be identified. The timing for the shutdown should be determined based on the process and equipment conditions, and this can be done through the program itself – there’s no need to use an external delay relay.
First, check whether all grounds are functioning properly; the working ground and the safety ground should be separated. Since the jump relay has activated, if there is interference, it means that this interference must last for at least 500 ms; the interference mainly comes from the 4-20 ms signals. Implementing an interlock memory function within the program is the most effective approach; judgment cannot rely on records from the upper-level computer.
What Chain Memory did was that, since there was nothing in Chain Memory, it came up with this method
Interlock memory stores all the data related to the interlock points at the time of the last trip, allowing one to immediately see which points caused the trip. If such a function exists, then why hasn’t the interlock system remembered it?