APPS: Mark 6 - VPRO diagnostic alarm, and IONet Error

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------------ Forwarded Message ------------
From: amam
To: AUTOMATION at CONTROL.COM
Subject: Re: APPS: Mark 6 - VPRO diagnostic alarm, and IONet Error

Dear CSA,

First of all, I am very sorry for the delayed reply, this is because we cannot do your proposed tests until the unit is out of service.

We first started to do some disabling for the monitoring contacts of the Relays of TREG from the toolbox. The problem was not solved.

Then we swapped the <Z> VPRO with <Y> VPRO, now we catch the problem's cause. The alarm swapped to <Y> VPRO, that means it was the <Z> VPRO. For the time being we have no spare, but we will order (GOD WILLING).

We are now experiencing a fatal MARK6 Error, causing the unit to shut down maybe every 15 days. That is the IONet communication error. We have two units controlled by MARK6. The commissioning was from approx 2 years. We got in the last two months many IONet errors, causing the Core <T>, and/or <R> especially to be out of service and not possible to get reset.

First we got an IONet 1 failure on VCMI R, we checked the coaxial cables of IONet 1 and no change, but when we opened the terminal resistor of this IONet and put again and RESET it accepts the reset. BUT the second day the unit tripped again by the same fault. We changed the VCMI of core R, and the unit was still ok for one month. After one month the unit tripped again and caused the other unit to trip because of the core <T> failure in both of them. First we found from our investigation the following alarm toggles in both units maybe thousands of times:

31-AUG-2008 00:44:27.303  K101  1 Q 0000      ALM ALARM XMIT SUSPENDED. CPU SWITCHED.
31-AUG-2008 00:44:27.303  K101  0 Q 0000      ALM ALARM XMIT SUSPENDED. CPU SWITCHED.

Then one unit tripped by controller failure and after 30 minutes the other failed.

Could you please clarify the meaning of such <ALM ALARM XMIT SUSPENDED. CPU SWITCHED>? And could you please tell me about your suggestions for the cause(s) and solution of this IONet problem?

Moreover, it supposes that we have TMR system, when one core IONet fails why does the unit trip?
Please advise me.

Best Regards.


On August 20, 2008, CSA wrote:
> It would seem to be odd that the alarm is being annunciated for an output that isn't being used, until one realizes that all of the Emergency Trip Relays are energized when the turbine is to be running. 
> 
> I believe the method for sensing a problem is that a set of contacts on each of the relays is used to check to see if the relay is energized or de-energized. Or, from GEH-6421, Vol. II, VRPO | TREG | Figure 'TREG Trip Interlocks and Solenoids', it would seem that possible the KZ3 relay might not be operating. You might try (with the unit not running), swapping KZ3 with KZ2 (I think the relay numbers are silkscreened on the TREG) to see if the problem follows the relay. If it doesn't, then I would suspect either the: 1) TREG card; 2) cable connecting the TREG to the <Z> VPRO; or, 3) the <Z> VPRO. 
> 
> Having said all of that, I don't think this alarm will ever cause a unit trip or forced outage. But, it is a nuisance Diag. Alarm. It's certainly worth trying exchanging the relays; if the problem follows the relay, then replace the relay. If it doesn't, then make sure the cable connecting the TREG to <Z> VPRO is firmly seated at both ends (when the unit isn't running!), and then start replacing components in the order listed above. 
> 
> Let us know how the troubleshooting progresses. Feedback is what makes the posts as control.com useful for many people; hopefully you've already done some searches on control.com and found some with feedback that are helpful (if not, use the 'Search' feature; it's very good!). <

( Complete thread: http://www.control.com/thread/1026249306 )