PLC test setup spike protection

[QGeek]

I am designing a simple test setup with an Crouzet PLC. I am concerned about fusing and voltage spikes or bounce that would damage the PLC or other components, or give false reads on the PLC inputs. I have no control, at this point, over the PLC code. I would like to mimic as close as possible the actual equipment, which consists of the following: Actual inputs are two 2-position joysticks (with center null), PEC outputs, and a series of relay outputs. Actual outputs are just relay inputs. The whole system operates on 24VDC, and the PLC instructions suggest a 1A quick-blowing fuse on the high side of the 24V to be used for both the PLC power and the PLC relay inputs. It also suggests an 1A fuse or circuit breaker for the 24V common. I am using a TDK-Lambda HK150A-24A power supply which output maxes out at 6.5A to run the entire setup. To mimic the actual equipment components, I would like to use toggle switches, and maybe LED lights. Does anyone suggest using pull-up resisors or diodes or some other form of de-bounce or spike nullifier, or should I be safe with just the toggle switches? The PLC inputs and outputs are relays.

 

[dV8r]

If you really want to mimic what is in use, use the same type of relays for your inputs ans outputs, look at the protection (if any) in the field and copy it too.

 

[QGeek]

Really good suggestion, thank-you.