Re: [foxboro] Hart FBM's

We found similar problem of measurement elevation in 2007 and we had production 
loss many times till March 2010 because of the trips occurred due to elevation, 
we installed the QF which doesn't address the root cause but at least it 
suppress the elevation.


________________________________
From: "DUNHAM, KENNETH J" <kdunham@xxxxxxxx>
To: "foxboro@xxxxxxxxxxxxx" <foxboro@xxxxxxxxxxxxx>
Cc: "SWAN, MICHAEL" <mswan@xxxxxxxx>; "STEINKE III, JOHN W" 
<jwsteinke@xxxxxxxx>; "DUNHAM, KENNETH J" <kdunham@xxxxxxxx>
Sent: Wed, August 25, 2010 12:13:02 AM
Subject: Re: [foxboro] Hart FBM's

Sheldon,


Re: I would be interested to lean who the other customers were that experienced 
this A/D Gain, and how their systems were affected.  And why  an advisory 
bulletin was never issued. Foxboro??



I can't answer that last part but we had a failure of FBM 214 executing a 
step-jump of about 25% in December 2008.  The issue only impacts 214's using 
current input.



We are a CE Pressurized Water Reactor nuclear generating station.



This resulted in an excursion of our Steam Generator Water Level and 
considerable operator confusion/concern.  Normal control was restored when we 
bypassed the affected channel (dual level inputs).  Since in our case, the step 
change did NOT exceed 100% input, the control system sensed a channel - to - 
channel deviation and defaulted to manual control, which it was designed to do 
(had the input exceeded 102%, it would have been declared "bad" and reverted to 
the remaining 'good' input).



We implemented the QF for CAR 1009770 at the time and updated the EEPROM image 
to  2.40C, which is the version currently installed.



It concerns me that you had this happen on 2.40D.  I will have to look into 
QF1013828.



We have not had any other FBM 214 issues to date but then again, we don't have 
very many (4).



Item Number


3.4


Title:


Quick Fix for CAR 1009770

Date:    09/30/08

CAR Number

CAR#1010386, HPS#17187

Quick Fix Number

QF1009770



Description:
Reports from 3 customer sites indicated that FBM214's would sometimes
shift all current signals upward by 20-30%. This was investigated and a
potential exists for this to happen if the AI background process didn't
have enough time to finish up before it was time to take another sample.
This problem was only seen on the FBM214's at site, not with the FBM216's.
(CAR#1010386 HPS#17187)

FCS Applicability Discussion

This item appears to be the exact failure experienced by FCS.  There is no 
record of Invensys notification to FCS of this potential problem.  This OE was 
discovered when specifically looking through the Foxboro database for a similar 
failure.






Feel free to contact me off-line if you need more info.



Kenneth Dunham
ERF/DCS System Engineer,
Fort Calhoun Station
9610 Power Lane, Blair, NE 68008
Mail Stop FC 1-9
Phone: (402) 533-6934
email: kdunham@xxxxxxxx<mailto:kdunham@xxxxxxxx>
Good judgement comes from experience.
Experience comes from bad judgement.
(Author Unknown)






-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On 
Behalf Of sssmith1@xxxxxxx
Sent: Tuesday, August 24, 2010 11:41 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Hart FBM's



Corry,

We have experience similar "infant mortality" problems with FBM214 TA's

during recent commissioning.  I believe we had 2 such failures.  None

since.

Technician wrote up the below technote capture for future diagnostics of

similar occurrences in house.

During Foxboro Controls installation and testing, we experienced loss of

control on a piece of equipment utilizing 4-20ma current loop of an

FBM214. Hart communication in this instance is only utilized for a

feedback indication. Upon discovery of this malfunction, we replaced the

suspected FBM module with a new one with no change of symptoms noted.

Further investigation led us to suspect that the problem was in the FBM214

Termination Assembly. Utilizing a digital ohmmeter, we checked the

resistance readings across terminals ?A? and ?C? of each input. It was

discovered that the input in question read approximately 80K-120K Ohms, as

compared to a normal reading of 8+Megohms on known good inputs. Readings

were taken with the module deenergized and field wiring lifted. We then

replaced the TA, and the problem was solved.





We have experience other HART FBM issues as well.

Most recently, last week we encountered issue where ALL CURRENT values

from a FBM 214 ( EEPROM version 2.40D ) experienced an abrupt gain across

all channels of approximately 20-30 percent.

Foxboro TAC told us that this was a known issue ( No technical advisory

bulletin ever issued??????)

A EEPROM new EEPROM update was released on Friday last week  (QF1013828)

that is supposed to partially address the issue.  They still don't know,

and I don't believe have been able to replicate the problem in house, but

this has occurred at 4 customer sites.  This could have been a very

catastrophic event, but fortunately, our IO and logic was partitioned and

segmented in such a way that disaster was averted.





We exclusively use CURRENT from the HART channels for control.  Do not

poll HART signals. for RIN's.  We do use RIN HART PV signals against our

215 hart AO's for deviation alarm purposes though.



During the HART AI gain event, the HART PV signal was unaffected, as

confirmed at the transmitter, via 375 hand held, and by PACWare

interrogation.

Scary to say the least.





I would be interested to lean who the other customers were that

experienced this A/D Gain, and how their systems were affected.  And why

an advisory bulletin was never issued.

Foxboro??

































Sheldon Smith

Office:972-884-2843

Cell:  214-460-4073

EFax:  866-734-2905

Conf:  877-253-4307 #7082843

Mailto: sssmith1@xxxxxxx





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