The PLC output remains unchanged; it returns to normal after the wiring is removed for a while
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The PLC output change indicator light changes in response to system changes, but the system output maintains a voltage of 220V at all times. The PLC output was normal for some time after the wiring was removed. After two failures, it was required that the neutral point of the electrical isolation transformer be grounded, and the control cables were replaced with shielded cables. After these measures were taken, the system has been in operation for two months without any further problems. This device has been in use for a year, and such a malfunction occurred suddenly. Could anyone explain the cause of this issue?
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Electricity generates magnetism, and magnetism generates electricity; AC220V induces electromagnetic effects. Generally, the output is sent to a relay, and it is necessary to choose a relay with strong resistance to electromagnetic interference.
This fault may be caused by poor contact at the PLC output, electromagnetic interference, or wiring errors. Firstly, poor contact can cause instability in the output signal, resulting in a constant 220V voltage being generated. Removing the connections and reconnecting them may improve the contact, thus temporarily resolving the issue. Secondly, electromagnetic interference can affect the normal operation of PLCs; this is particularly evident in high-voltage environments. Therefore, replacing the shielded cable can effectively reduce interference and improve system stability. Finally, grounding the transformer’s neutral point helps prevent electrical faults caused by poor grounding. Through these measures, the electrical connections were improved and interference was reduced, thereby restoring the normal operation of the equipment. .
If connecting directly to PLC contacts, static interference should be taken into consideration