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Option 81 - Cabinet Breakers tripping multiple times

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tazada

IS-IT--Management
Dec 7, 2010
4
US
Not a Nortel tech, so bear with me. I know enough to be dangerous.

We have an option 81 that has been running great since it was turned on almost 20 years ago now. We have the first fiber connected remote shelves Nortel made. At our remote fiber connected sight across campus we have 7 loops spread across two cabinet stacks, one with three shelves, one with four. We are still running a very early release (19). Both stacks run from the same DC plant (2 x 25A rectifiers), and also tied to a (replaced 1 yr ago) string of batteries.

Thursday we had all loops in the four stack cabinet go down. When we looked at the cabinet, all five breakers at the base were tripped including the blower breaker. Resetting the breakers yielded all but one of the shelf power supplies dead along with all four ring generators. Scramble to get new parts, everything back up and running. Chalk it up to bad power...until we get a call Saturday. Same thing. All breakers in the stack with four loops / shelves tripped. Idling inches away is the stack with three loops / shelves never missed a beat. Resetting breakers this time showed no bad power supplies but a single ring generator that did not survive. All loops came back up and after babysitting 8 hours thought all was good. Sunday's phone call same thing. Upon resetting the breakers, nothing died and loops came back up. Just for good measure, we replaced the one power supply that had survived the original outage. Last night everything stayed up.

The only thing unusual is we got no alarms from our service company when the loops dropped. Also, the main alarm light on the stack is flashing 3 times. Long - short - short. Our vendor has no idea why, and is happy to chalk the three trips up to bad power, although the cabinet right next to it never had issues.

We get significant CRC errors etc. on the console from only one of the downed loops (24) when the breakers are tripped and can only be halted by DISL 24 in LD20.

I do not believe this to be power related since the other stack has been running fine with no issues. we have checked all grounds and DC supply distribution to ensure all connections are tight. DCV is -53, current draw is 25A with all 7 shelves fully loaded with mostly analog and average of 5 Digital cards per shelf.

Any suggestions ideas? I have my fingers crossed the phone will not ring tonight (Again, monitoring company not calling, Public Safety calls when the alarm panels across campus loose dialtone and start beeping)

Sorry so long, let me know if you need any other info that could be helpful.

Thanks in advance,
Allen
 
Try pulling your system monitor card in the pedestal base as that it will cause your shelves/columns to drop. It is possible that the system monitor card is bad.
 
As telemon suggests could be system monitor
May also be your 'Blower' failing serving that stack...I guess system monitor is detecting overheating ?

Cheers!!
 
We had a DC powered switch that did the same thing and it turned out to be a bad System Monior (as referred to by telemon). Ended up changing the main and the one for the column that was tripping. Once we did that it all worked fine.

John
 
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