YETS 2017-2018 & LS2 Works EN-EL / Power distribution On behalf on EN-EL

EN-EL IMPACTS for the YETS 2017-2018 & LS2 Summary The whole site Meyrin SPS LHC Maintenance Projects and maintenance works on substation 400 kV & 66 kV

EN-EL IMPACTS for the YETS 2017-2018 & LS2 The whole CERN Projects New main substation for secured network (ME91) (YETS + before LS2) Underground access prohibited at LHC1, BA6 & BA7 during transfert of loads Connection of new 400 kV substation BE2 to main 66kV substation (before LS2) Renovation of the 400 kV protection and control system (BE) (LS2) Consolidation 400 kV et 66kV substation (LS2) Refurbishment ME9 substation (LS2) Lots of power cut on SG Meyrin Replacement of the AutoTransfer automatism (PLC) Maintenance Maintenance UPS, 48V, transformers, HV & LV switchboard Tests Annual test for secured network 10’ power cut of « General Services » & « Secured » networks at 6:00 am in a working day (YETS + LS2) Prohibited access in underground Auto-transfer test (YETS + LS2) Prohibited access in underground + limited power PS – Booster impacted only a week-end on the Meyrin site Meyrin - LHC1 - LHC18 - BA6 - BA7 Secured network not available only Saturday in working hours ! All other sites (SPS – LHC – 513 – MEY without PS – Prevessin – ZN…) repowered without power cut on degraded configuration during the week-end BE2 YETS 2017-2018 – Works EN-EL / Power distribution On behalf on EN-EL

EN-EL IMPACTS for the YETS 2017-2018 & LS2 Meyrin site Projects Consolidation electrical network PSB + LIU upgrades (YETS + LS2) Consolidation electrical network PS + LIU upgrades(YETS + LS2) New main substation for secured network (ME91) (YETS + before LS2) Underground access prohibited at LHC1, BA6 & BA7 Refurbishment ME9 substation (LS2) Lots of power cut on SG Meyrin Connection new compensator to main machine substation ME59 (TE-EPC) (LS2) Maintenance Maintenance UPS, 48V, transformers, HV & LV switchboard Tests Annual test for secured network 10’ power cut of « General Services » & « Secured » networks at 6:00 am in a working day (YETS + LS2) Prohibited access in underground Auto-transfer test (YETS + LS2) Prohibited access in underground + limited power AUG 4-5 days (YETS + LS2) Prohibited access YETS 2017-2018 – Works EN-EL / Power distribution On behalf on EN-EL

EN-EL IMPACTS for the YETS 2017-2018 & LS2 SPS Projects 48Vdc system replacement BA7 (YETS) 1st general power cut early YETS et 2nd 2 weeks after Replacement of the Emergency lighting BA3 (YETS) Crab cavity BA6 (RF) (YETS) Refurbishment SPS substation 18kV & 400V (BA1, BA2, BA3, BA4 & BA6) (YETS + LS2) Replacement of the Emergency lighting BA1, BA2, BA4, BA5, BA6 & BA7 (LS2 - 6 weeks/point) New BAF3 substation (RF) (before LS2) Connection of new compensator BEQ1 to main machine substation Prevessin site (LS2) Maintenance Maintenance UPS, 48V, transformers, HV & LV switchboard Tests Annual test for secured network 10’ power cut of « General Services » & « Safety » networks at 6:00 am in a working day (YETS + LS2) Prohibited access in underground Auto-transfer test (YETS + LS2) Prohibited access in underground + limited power AUG 1 day by site on working days – Arcs affected (YETS + LS2) Prohibited access in underground BA6 & BM6 YETS 2017-2018 – Works EN-EL / Power distribution On behalf on EN-EL

EN-EL IMPACTS for the YETS 2017-2018 & LS2 LHC Projects Refurbishment LHC18 substation (UPS & 48V) (YETS) 2 days of power cut during AUG LHC DIESEL consolidation (LHC2, LHC3, LHC3Z, LHC6 & LHC8) (TS + YETS + LS2 ) Safety network unavailable 3 weeks with many cuts Refurbishment LHC18 substation (18 kV & 3.3 kV) (LS2) 2 months of power cuts (April - May 2019) HL - LHC (LHC1, LHC4 et LHC5) (end of LS2) HL-LHC works Deviation cables for creation UPR (during YETS) Works on 3.3 kV in LHC4 (during LS2) Works for connection of new HL-LHC galleries (end of LS2) Maintenance Power transformers 66kV maintenance works (LS2) réseau machine en puissance réduite Maintenance UPS, 48V, transformers, HV & LV switchboard Tests Annual test for secured network 10’ power cut of « General Services » & « Safety » networks at 6:00 am in a working day (YETS + LS2) Prohibited access in underground Auto-transfer test (YETS + LS2) Prohibited access in underground + limited power AUG 9 days, 1 day by site on working days – Arcs affected (YETS + LS2) Prohibited access in underground Test redundancy UPS (end of LS2) YETS 2017-2018 – Works EN-EL / Power distribution On behalf on EN-EL

EN-EL IMPACTS for the EYETS 2016-2017 Maintenance works on 18 kV, 3.3 kV and LV networks 1/3 of the equipment 18 kV et 3.3kV : 400 cubicles General services LV switchgears Safety network LV switchgears Planning - requirements Slots of 5 to 6 days for each LHC points + BA5 & BA7 (including the AUG tests on the last day) and limited access on site (as done during LS1) No underground access for 2 to 3 days (secured network not available) No handling operations for 5 days (distribution off  cranes off) No 18 KV maintenance during 400/66 kV maintenance operations No secured network maintenance while AUTOTRANSFERT is off Necessary coordination with CRG & CV EYETS 2016-2017 – Works EN-EL / Power distribution On behalf on EN-EL

EN-EL IMPACTS for the YETS 2017-2018 & LS2 Projects and maintenance work on substation 400 kV & 66 kV Projects Replacement bushings on the 3 transformers 400kV/18kV (LS2) Replacement 18 CTs 400kV (LS2) + 3 CTs 66kV (before LS2) Installation new incomer 400kV EHD6/BE (LS2) Installation of fire walls (LS2) Consolidation 400 kV protection and control system + auxiliaries (LS2) Fire protection system consolidation on transformers and 400 kV substation (LS2) Maintenance Power transformers 400 kV and 66kV maintenance works Maintenance of the 400kV and 66kV circuit breakers works Tests on RTE interface protections and various signals YETS 2017-2018 – Works EN-EL / Power distribution On behalf on EN-EL

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