allen bradley panel troubleshooting

[Anurag 0]

i am facing a problem , the allen bradley control panel is getting frequentlly tripped  and then it reboots automatically.

(i am a maintenance engineer in a automotive parts supplier industry and this issue is  causing  serious downtimes)

 

help and suggestion needed

 

thanks in advance

 

[PLCMentor.com 60]

Is the panel actually tripping anything or shutting down and starting back up again?  If it is flaky with suddenly powering off, you may have a bad power supply.  That can cause strange things like that to happen.

[Michael Lloyd 85]

Which Allen-Bradley? Control Logix, Compact Logic, SLC, Micrologix?

Do you have software to see what the diagnostic codes, if any, are? The rebooting all by itself "kind of" says it's not a PLC problem. It's a little disturbing that the logic might do that but I don't work in that industry.

I would tend to agree with the power supply being a problem. A backplane problem would, usually, fault the processor (and be a real PITA).

Edited 12 Jul 2016 by Michael Lloyd

[PLCMentor.com 60]

Funny I had just assumed from his post that it was a SLC (you know where that usually gets you).  I think that it is the only AB I have had this problem with and it always seemed to be the power supply. 

[Michael Lloyd 85]

WE just replaced a CLX rack that kept faulting the processor on a bad DI card. That's the only reason I asked :)

 

Should add that the card was fine.

Edited 12 Jul 2016 by Michael Lloyd

[PLCMentor.com 60]

Interesting and I'm sure that was fun to track down!

I guess we should add that not only would they processor type be good to know, but explain exactly what you mean by "tripping."  Is it a cabinet power down, processor power down, fault, or other?

[drforsythe 15]

I agree with PLCMentor- we need to know exactly what is "tripping".  Is it the whole cabinet or just the plc?  If the problem is intermittent, it may require you to monitor several things with a meter that can record the values against time.  Is your PLC powered by AC or DC power?  I would monitor the incoming power, any DC power supplies and try to relate that to what is happening in the process when the fault occurs.  If your main power is staying up, but your DC supply is dipping, then it could be related to a load that is putting your power supply into a current limiting protection mode.  If your AC power is not consistent, try to relate when the fault occurs to the time of day.  Are other machines having the same problem?  Does the fault occur at the same time(s) daily?  If so, it could have to do with how your neighbors are using the power or it could also be the power company inserting or removing correction capacitors to manage the power factor.

[Anurag 0]

@Michael Lloyd ya i forgot to mention for the control logix (RS logix 5000)....the problem is resolved now...i found the incoming supply was fluctuating beyond the limit of the siemens phase sequence relay causing it to shutdown n automatic reboot....we have here corrected the incoming supply problem...

@PLCMentor.com yup you were ryt about the bad power supply... :)

(y)

[PLCMentor.com 60]

Well it sound more like a supply power problem than a power supply problem...