18 kV network review and status of the SPS consolidation plan D Bozzini on behalf of ENELHT With the contribution of ENELOP section members and in particular G Fernqvist G Cumer ID: 526800
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Electrical network:18 kV network review and status of the SPS consolidation planD. Bozzini on behalf of EN-EL-HTWith the contribution of EN-EL-OP section membersand in particular G. Fernqvist, G. Cumer & C. Jach
ATOP Days - Session 4 - Technical infrastructure Slide2
OutlinePART I Major events on HV electrical cable network in 2008 Major events on HV cells in 2008 Historical trend of failures on the SPS 18 kV network CASE 1: The 2008 SPS joints crisis CASE 2: BQ1 Compensator CASE 3: RESTO 1PART II SPS Consolidation, status and future program BE-TI8 network layout SMB: what do we do? Failure location on HV cables networkCONCLUSIONS Slide3
Major Events on HV Electrical cables Network SPS 18 kV network6 cable failures on the 18 kV network (Including the 4 ones mentioned by P. Sollander)2 on the pulsed TI8 network, stop of the SPS machine (2001)3 on the pulsed network, operation of SPS possible in open loop (1970)1 failure on the SMB1, redundant network available (1970)BEQ1 CompensatorFailure on a 18 kV cable head of the BEQ1 feeder in BE substation, fortunately not in operation during failure period (
2003
)
RESTO 1
Meyrin
Elastimold
18 kV elbow connector on a transformer powering the general services of
Resto
1. (
2001)
Near miss failure detected tanks to the preventive maintenance and the reinforced visual inspections of the installation by the operation section.Slide4
Major Events on CERN HV cellsME24 cell explosion ( 1995)10 days stop of the machines feed through the ISOLDE loopSE18 near miss ( 1995)Preventive action takenProblem limited to FLUAIR cell type on Meyrin substations and SE18Monitoring of temperature and humiditySystematic Partial Discharge (PD) corona effects measurementsVisual inspection inside cells whenever accessible Comments: In the past 5 years, 2 similar accidents and 3 near miss !
ME59
switch closing failure during auto-
tranfer
exercise (
19
68)
Design life time 25 years, continuous operation at CERN 41 years !
Comments: Remember the 29 July 2006, same type of
equipment !
ME9 Jura substation (
19
68) critical installationSlide5
Historical trend of failures on the 18 kV SPS networkNature of the failures A) Aged cables, made with XLPE affected by water-treeing effect B) Not directly the cable but the accessories (joints, terminals)
Remarks for 2008
4 out of 6 failures affected recently installed SPS network segments (
2001)
2 remaining failures on old cablesSlide6
CASE 1: SPS joints crisis (1) - FailuresSlide7
CASE 1: SPS joints crisis (2)- AnalysisSlide8
CASE 1: SPS joints crisis (3) - AnalysisAnalysis of the jointsConclusions of ALL 8 joints examined
ASSEMBLY PROCEDURE NOT FOLLOWED
POOR QUALITY OF WORKSlide9
CASE 1: SPS joints crisis (4) - RepairCorrective actionsRepair of all joints that failedPreventive actionsReplacement of all jointsImprovement of the shielding continuity across the joints 2 new joints for each repair/replacement
Now we have 80 joints instead of 40Slide10
CASE 1: SPS shield currentsPreventive action68/80 joints have a reinforced shield continuityModified assembly procedure approved by joint manufacturerStandard
Reinforced shield continuity
Signs of heating confirmed by the conclusions of the joints analysis
This triggered a campaign to measure shields currents
Sources and reasons not yet fully understood
100 A/divSlide11
CASE 2: BEQ1 compensator – 18 kV cable terminal failureConclusionASSEMBLY PROCEDURE NOT FOLLOWEDPOOR QUALITY OF WORK
Failure on a 18 kV cable terminal
Date of installation 2003, place BE, Indoor
Discharge to ground without load
Analysis by third party (
Cellpack
Laboratory, DE)
Outcome of the analysis
Length of insulation dimensions not done according to the procedure
Use of inappropriate tooling (knife) causing serious weaknesses on the insulationSlide12
CASE 3: RESTO 1 - Elastimold 18 kV elbow connector failureFailure on a 18 kV Elastimold connector Date of installation 2003, place Bdg 500, Indoor Discharge to ground, circuit was on load Analysis by third party (Cellpack Laboratory, DE)Outcome of analysis Preparatory dimensions not done according to the procedure Use of inappropriate tooling (knife) causing serious weaknesses on the insulation
Conclusion
ASSEMBLY PROCEDURE NOT FOLLOWED
POOR QUALITY OF WORKSlide13
SPS Consolidation - Status on March 200918 kV cable network (SMB not included) and substationsMarch-09
Segment
Length
Stable
Pulsed
[m]
Done
Done
BE-B3
350
350
350
B3-B4
1300
1300
1300
B4-B5
1350
1350
1350
B5-B6
1260
B6-B7
550
550
550
B7-B1
1100
B1-B2
1520
B2-BE
1100
1100
Total [m]
8530
4650
3550
Done [%]
55
42Slide14
SPS Consolidation – Short term work planFrom March 2009 till December 2010Install cables between BA6-BA6 (2X), BA1-BA2 (2X), BA2-BE (1X)Digging 6.6 kmPrepare renovation of substations BA4 and BA2Define and implement scheme for parallel coupling of the BE-TI8 antenna with BE-BA4 pulsed loop
During shutdown
2010-2011
Commissioning of installed cables
Renovation
and commissioning of substations in BA4 and BA2
Installation and commissioning of parallel coupling BE-TI8 with
BE-BA4 pulsed loopSlide15
SPS Consolidation – Mid term work planBy the end of shutdown 2012Installation and commissioning of cables between BA4-BA1 (2X)Digging 1.1 kmRenovation and commissioning of substations BA1 and BA3By the end of shutdown 2013
Renovation and commissioning of substation BA6Slide16
BA4-TI8 network layoutSituationPower line added in 2004 to power the CNGS experimentOn this line we also have the SPS stable network for BA4Not being part of a loop -> no redundancy for powering CNGS and SPS pulsed network in BA4Consequences
If a fault appears on this line (ex: joint to be replaced), one week of shut down minimum
Remedies
Implement
possibility to operate the TI8 line in // to the SPS pulsed loop from BE to BA4Slide17
SMBConsequencesIf a fault appears on this line, one week of shut down minimum of the affected segmentHow to proceed?1) Receive guidelines whether to include these circuits in the EN/EL SPS consolidation mandate or:2) as recommended by the ATC on 27th Oct. 2006 study and find procedures for a fast repair and shorten DTTR
Situation
Old power lines affected by water treeing effect
(
1970)
Failure rate going up with the time
Operation is not 100 % redundant (see 4
th
ATC minutes 27
th
October 2006)
Fully operated by TE-EPC, maintained by EN/ELSlide18
Failure location on HV networkCurrent procedureAs soon as a failure is detected, ERDF (Electricite Reseau Distribution France) is contacted and they intervene on average within three days to precisely localize the failure.Technique In most of t he cases reflectometry coupled with a pulsed surge generator.LimitsTime of intervention depends on availability of ERDF. Also to consider that EDF network diagnostic has priority with respect to CERN
.
How to improve
EN/EL has almost all the equipment to perform the same type of diagnostic
A bit old but can be upgraded with a dedicated budget
Today there are weaknesses on expertise, but if necessary on a short mid term period we can envisage to set up a EN/EL team for such diagnostic
What is needed?
Dedicated personnel, time for set-up and time for training on real casesSlide19
CONCLUSIONFailures6 out of 8 major failures or near miss are related to bad assembly of HV componentsFor the SPS, except for the “joint crisis”, 2008 as not been a bad year, 2 faults due to aging cables. One affecting SMB. But…remember what we saw on the video!Cells and substations: let us not underestimate the status of ME59 and ME9Serious problem of HV components assembly qualityIdentification of specialized firms in ongoing with good resultsIn-house expertise must be improved in
order to follow the execution of repair
High currents in SPS shields
Require more time to investigate the sources of these currents
Consolidation of SPS 2009-2010 (assuming LHC will run over the winter)
Installation of cables on two segments (BA5-BA6 and BA7-BA1)
Re-configure substations in BA2, BA4 and improve the TI8 network layout
Require solid budget and availability of sufficient and fully qualified personnel
SMB: We need to know now what to do
Failure location: there is room for improvement of the MTTR