How Will PLCs Behave If The Power Supply Voltage Drops Momentarily?

Modified on Sun, 11 May, 2025 at 10:10 PM



The PLCs behave in the following ways if the power supply is interrupted or the power supply voltage drops.
  • If the power supply falls below 85% of the rated voltage, the CPU Unit will detect a momentary power interruption, will stop operation, and will turn OFF the outputs depending on the length of the interruption.
  • The CPU Unit will not respond to the power interruption and will continue to run unconditionally if the power is interrupted for less than 10 ms
  • If the power interruption lasts more than 10 ms but less than 25 ms, the CPU Unit may or may not respond to the power interruption. In this case, the operation of the CPU Unit cannot be predicted.
  • The CPU Unit will stop unconditionally if the power interruption lasts more than 25 ms.

 

 


 

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