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ATOP Days - Session 4 - Technical infrastructure

ATOP Days - Session 4 - Technical infrastructure . Electrical network: 18 kV network review and status of the SPS consolidation plan D. Bozzini on behalf of EN-EL-HT With the contribution of EN-EL-OP section members and in particular G. Fernqvist , G. Cumer & C. Jach. Outline.

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ATOP Days - Session 4 - Technical infrastructure

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  1. ATOP Days - Session 4 - Technical infrastructure • Electrical network: • 18 kV network review and status of the SPS consolidation plan • D. Bozzini on behalf of EN-EL-HT • With the contribution of EN-EL-OP section members • and in particular G. Fernqvist, G. Cumer & C. Jach

  2. Outline • PART 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 1 • PART II • SPS Consolidation, status and future program • BE-TI8 network layout • SMB: what do we do? • Failure location on HV cables network • CONCLUSIONS

  3. Major Events on HV Electrical cables Network • SPS 18 kV network • 6 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 Compensator • Failure 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.

  4. Major Events on CERN HV cells • ME24cell explosion ( 1995) • 10 days stop of the machines feed through the ISOLDE loop • SE18near miss ( 1995) • Preventive action taken • Problem limited to FLUAIR cell type on Meyrin substations and SE18 • Monitoring of temperature and humidity • Systematic Partial Discharge (PD) corona effects measurements • Visual inspection inside cells whenever accessible • Comments: In the past 5 years, 2 similar accidents and 3 near miss ! • ME59switch closing failure during auto-tranfer exercise ( 1968) • Design life time 25 years, continuous operation at CERN 41 years ! Comments: Remember the 29 July 2006, same type of equipment ! ME9 Jura substation ( 1968) critical installation

  5. Historical trend of failures on the 18 kV SPS network • Nature 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 cables

  6. CASE 1: SPS joints crisis (1) - Failures

  7. CASE 1: SPS joints crisis (2)- Analysis

  8. CASE 1: SPS joints crisis (3) - Analysis • Analysis of the joints Conclusions of ALL 8 joints examined ASSEMBLY PROCEDURE NOT FOLLOWED POOR QUALITY OF WORK

  9. CASE 1: SPS joints crisis (4) - Repair • Corrective actions • Repair of all joints that failed • Preventive actions • Replacement of all joints • Improvement of the shielding continuity across the joints • 2 new joints for each repair/replacement • Now we have 80 joints instead of 40

  10. CASE 1: SPS shield currents • Preventive action • 68/80 joints have a reinforced shield continuity • Modified assembly procedure approved by joint manufacturer 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/div Standard Reinforced shield continuity

  11. CASE 2: BEQ1 compensator – 18 kV cable terminal failure • Conclusion ASSEMBLY PROCEDURE NOT FOLLOWED POOR 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 insulation

  12. CASE 3: RESTO 1 - Elastimold 18 kV elbow connector failure • Failure 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 WORK

  13. SPS Consolidation - Status on March 2009 • 18 kV cable network (SMB not included) and substations

  14. SPS Consolidation – Short term work plan • From March 2009 till December 2010 • Install cables between BA6-BA6 (2X), BA1-BA2 (2X), BA2-BE (1X) • Digging 6.6 km • Prepare renovation of substations BA4 and BA2 • Define 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 loop

  15. SPS Consolidation – Mid term work plan • By the end of shutdown 2012 • Installation and commissioning of cables between BA4-BA1 (2X) • Digging  1.1 km • Renovation and commissioning of substations BA1 and BA3 By the end of shutdown 2013 • Renovation and commissioning of substation BA6

  16. BA4-TI8 network layout • Situation • Power line added in 2004 to power the CNGS experiment • On this line we also have the SPS stable network for BA4 • Not being part of a loop -> no redundancy for powering CNGS and SPS pulsed network in BA4 Consequences • 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 BA4

  17. SMB Situation • Old power lines affected by water treeing effect( 1970) • Failure rate going up with the time • Operation is not 100 % redundant (see 4th ATC minutes 27th October 2006) • Fully operated by TE-EPC, maintained by EN/EL • Consequences • If a fault appears on this line, one week of shut down minimum of the affected segment • How 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

  18. Failure location on HV network • Current procedure • As soon as a failure is detected, ERDF (ElectriciteReseau 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. • Limits • Time 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 cases

  19. CONCLUSION • Failures • 6 out of 8 major failures or near miss are related to bad assembly of HV components • For 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 ME9 • Serious problem of HV components assembly quality • Identification of specialized firms in ongoing with good results • In-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

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