Fusing PLC outputs ??

[milmat1]

Engineers and designers, question.


Do you typically fuse the PLC outputs ?

I see some that are fused and many that are not. I typically fuse the AC outputs, but rarely the DC.
And sometimes I consider what the load is going to be. Pilot lights, relay's or solenoid valves etc.


Just curious about your thoughts and practices??


Thanks
Matt

 

[widelto]

Output modules: Basically 1 fuse for each output, no matter how many outputs a single module has.
Input Module DC : 1 fuse for 8, 16 inputs module (power supply)
Input Module AC: 1 fuse for input module.

 

[JesperMP]

Both AC and DC outputs are protected by circuit breakers. The outputs are grouped with one CB for the same function for which the outputs are related to, not related by the PLC hardware.
The granularity of how many outputs per CB is acceptable is a best estimate of how severe will the consequences of a tripped CB versus the practicality of how many CBs you will get in the cabinet.

An alternative for DC outputs is to use PLC output cards with integrated current limitation and diagnostics on each channel. Then you can limit the consequences of an short-circuit or overload to the minimum.

 

[milmat1]

Thank you for the input (no pun intended....lol)