D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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 ATOP Days - Session 4 - Technical infrastructure

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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.

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March Major Events on CERN HV cells –ME24 cell explosion (  1995) 10 days stop of the machines feed through the ISOLDE loop –SE18 near 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 ! –ME59 switch 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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 out of 6 failures affected recently installed SPS network segments (  2001) 2 remaining failures on old cables

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March CASE 1: SPS joints crisis (1) - Failures

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March CASE 1: SPS joints crisis (2)- Analysis

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March CASE 1: SPS shield currents Preventive action 68/80 joints have a reinforced shield continuity Modified assembly procedure approved by joint manufacturer Standard 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/div

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March SPS Consolidation - Status on March kV cable network (SMB not included) and substations March-09 Segment LengthStablePulsed [m]Done BE-B3350 B3-B41300 B4-B51350 B5-B61260 B6-B7550 B7-B11100 B1-B21520 B2-BE1100 Total [m] Done [%] 5542

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March SMB 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 27 th Oct 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/EL

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March Failure location on HV network Current procedure As 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. 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

D. Bozzini, EN-EL-HT, ATOP Days 2009, 4-6 March 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 (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