Quantum Modicon PLC and Cummins Generator Sets

The module is getting a signal from somewhere, so you need to find out where. Do you have software to access the PLC? Is the program written in Concepts or Proworx? Your getting 24vdc from somewhere. Check in the program to see what that input is actually suppose to do. If the circuit breaker doesn't have an auxiliary contact, then is there a relay somewhere that provides the signal?

A schematic will help. I you wish to send a copy by email, then I can help further.

Hello rrnut-2,

I don't have any software for the PLC. I checked the input wire and it was low (0 vdc) at the PLC (the DDI 353 10 reads ground as an active input). However when I checked the other end at the terminal block, it was reading high (24 vdc), so I said to myself it's a misswire. But when I came back to work the next morning the input was high at both the TB and the PLC?? But the active point for that input still won't reset. This particular input comes from the local/remote switch of an 11 kv transformer breaker for the generator. It is interlocked with the generator breaker to prevent closing the generator into a no load condition. Therefore, I have to clear the alarm or the generator breaker will trip shortly after closing. I wish I had a program, but all I've got is the wire numbers and the corresponding PLC inputs. PS I've been trying 4 months to get some decent drawings (no luck). Thanks for your help!

hughes838

It's tough without a schematic. One thing that you could try; remove the wire and and cycle the input with a separate 24vdc supply. You will have to make sure that you have the correct polarity for the test to work, even though the module can be wired either sourcing or sinking, you will want to stay in sync with the rest of the system. If the light still doesn't go out, then it is a bad module. This will at least tell you whether it is the module or the rest of the system.

Hello again, I thought about that but (did I forget to mention) this power station provides 100% of the power for an Army depot in Iraq. If I slipped or there was a difference in potential I could dump the whole place (and lose my job). I did remove the wire though, from the PLC but the input still didn't change states. We don't have any spares either so I couldn't fix it anyway. Cheap outfit! I agree with you it looks like a bad module and not the system because all the rest of the 32 inputs are OK. If I had the software, I could force it open I suppose........ I appreciate your time, if I ever get it fixed, I'll let you know what the problem was. Take it slow. ERH

When I get home tonight I'll see if I have one. If I do, I'll send it to you.

One thing that I will warn you about is, this. These modules in the Quantum series are hot swapable. However, depending on how it was programmed, the program could be looking for module faults. If it is, and you remove a module, the PLC could shut down on error and lock up on fault. You won't know this unless you could look at the program. This is not normal, it has to be programmed in with Modicon PLC. So just to be on the safe side, you will have to shut down the whole system to change the module.

Just thought that I should warn you.

Wow! You are right, well, we'll have to wait until all those units can be shut down to try this. Or if I could ever get the software, I could just look at the program. Thanks, guy, for telling me about the program and module faults. I would have swapped it out without thinking. Ed H.