Power Generation: Product Operation and Maintenance

[ieenterprises]

  HI Guys got a tricky one here the ISO shuts down the engine randomly with a low oil pressure shutdown. Also random PLC fault shutdowns. The oil is new and full and both oil pressure switches have been replaced. The pressure drops to fast on the trend so it looks like a electrical issue of coarse. There is no AL4 fault that ever shows up when this happens so I think its the ISO because the fault is on the ISO screen and not the generator pannel. It could run for weeks perfectly and then all of the sudden a shutdown out of the blue. Anybody run into this problem before or something like it.

[mikel]

Are you sure the ISO switchgear is also generating a low oil pressure shutdown, instead or reading the fault from the unit?  I assume you have an EMCP II Plus? Do you have CAT ET? Can you datalog the oil pressure as seen by the ECM and see if it's dropping out?  How old is this system?  Are you using a CCM or a PL1000E for comms? What has been ISO's response?

What kind of PLC fault are you getting? A loss of power, processor fault, I/O fault, what?

Mike L.

[ieenterprises]

It was installed new in 2008 I have ET yes. The funny thing is that  we have 2 engines 3520 and they both will shut down on this alarm also they have both shut down on other alarms too like high inlet temp but if you look at the cat ET the inlet temp was never high. On the low oil pressure shutdowns the oil pressure is not dropping out I have verified that. The ISO is showing the shutdowns not the generator. The plc faults say on the ISO screen PLC Fault there is no defenition of what it is just PLC Fault. There is nothing wrong with them they have been changed. I guess it doesnt seem like a common problem because not much feedback on the problem. Cat cant fix it and the ISO guy cant fix it but I will in time and I wont give up till its fixed. By the way we use a pl1000e and there are ccm,s in each breaker cabinet. Thankyou for your time Mike I appreciate it.  603-833-3911

[RM_FNTS]

Is this an EMCP 3.s project or Modicon PLC based project? or other

I cant believe that ISO hasn't sorted this issue Usually they are very accomodating (in my experience)

Some of the best ISO techs are in your area (in my opinion) (according to your area code) maybe your not speaking to the right channel.

Seems like the controller (ISO) is intermittently loosing comms to the PL1000, or miss interpreting them.

why are there PL1000 and CCM's?

[ieenterprises]

Your right it seems like a communication or some sort of problem like that. Im using a modicon based plc project and why there is a pl1000 and the ccm's together im not sure I would have to talk to the engineer about that. So there  is nobody out there that has this same issue so that lets me know this will be an oddball problem to figure out. Thanks for the help guys any other insights feel free.

[RM_FNTS]

First of all, not having intimate knowlege of your particular system makes comments difficult to be accurate.

I have also not done an ISO project with a 3520 or PL1000, but have been involved with many other configurations.

Having said that take my comments for what they are worth.

The 3520 and / or PL1000 may have some specific code regarding engine comms that could be contributing to the issue

You stated that you are getting PLC fault on the touch screen. Is this a general alarm or specific to a gen PLC?

It was also stated that the PLC was replaced and the problem is still there.

Has the Modbus + network been verified to be intact, teminations, cable integrity, topograpghy, shielding etc. verify termination resistors are intact and at the correct locations.

Make sure the network is clear of current carrying conductors (Induced EMF)

Is there fibre in the network? I have seen dirty fibre connections cause strange issues.

What is the system voltage? MV systems use different network cable than low voltage

These suggestions are basic and one has to assume they have already been eliminated, but sometimes in troubleshooting we cant see the forest for the trees.

My knee jerk reaction from this side of the WWW is either a cable / network issue or code issue.

Hope this helps

[RM_FNTS]

2 more cents to add

Ask ISO how they are shutting down the engine on low oil pressure.

If they are taking the raw data and creating their own alarm it may need a time delay (or longer delay)

Usually they use the raw data for graphics only, typically the actual shutdown is derived from the shutdown word over the cat network via PL1000 / CCM

Being a 3520 PL1000 project it may be different than what I have been exposed to

PLC faults are a different issue but may be related

[CAT-ISOsims]

@ Ieenterprises - I hope that your issue has been resolved, but if not here is an explanation of the issues that you are having:

1.)    Majority of the engine pre-alarms and shutdown alarms (i.e. high coolant temp, low coolant temp, low oil pressure, low coolant level, E-stop, overcrank, overspeed, etc.) are derived by the engine.  The PLC communicates with the CCM and polls the engine data via Modbus (RS-232).  The PLC then interprets the shutdowns and the pre-alarms messages and passes them through the logic and annunciates the alarms when they come in.  

If you get an alarm from the switchgear, but not on the engine, it probably means that you’re getting a garbled message.  Double-check the security of your communications cables 1.) Data link and 2.) RS-232 (thin grey wire).  If your connections are fine, double-check all off your grounding/shielding on the engine.  

2.)    The PLC fault alarm originates from the AP1/AP2 PLC.  All of the PLCs send a “PLC ok” bit to both the AP1 and AP2 PLCs.  If the AP PLC does not receive that bit (either the PLC is powered down/failed or loss of communications) then the system will annunciate a PLC fault. Usually if the fault comes in and out quickly it’s a communications issue.

ISO helpdesk:  866-883-3879