Giorgio on behalf of ELQA team ELQA plan for LS2 Introduction ELQA ELQA into general planning Activities per sector Hardware & Manpower Safety aspect Add slide with introduction what is ELQA… Test types, etc… The goal of ELQA is to validate the entire chain of circuit and instrumentation included! Giorgio on behalf of ELQA team

ELQA: Introduction The electrical quality assurance concerns all superconducting circuits of the LHC machine (more than 1600 circuits). The objectives of the ELQA tests are: Electrical qualification of each superconducting electrical circuit, including the current leads and the active systems connected to the circuit. Measurement of electrical parameters of each superconducting electrical circuit in order to verify reference values for the initial operation of the power converters and for the machine operation. Verification of the integrity of the instrumentation used for the protection of the superconducting magnets and current leads. All the ELQA tests are documented, based on approved procedure, with predefined conditions and safety aspects The parameters of the circuits are stored in DB (Electrical Layout DB) The ELQA test results are recorded in ELQA DB The follow-up of a circuit is ensure via Manufacturing and Test Folder (MTF) as a part of EDMS Non Conformities are reported and stored in MTF

ELQA: When ? Machine assembly: Hardware Commissioning of the machine: ELQA tests were present during machine assembly to ensure the circuit correctness (Arc Interconnection Verification or AIV procedure, Partial Arc Qualification or PAQ procedure). Hardware Commissioning of the machine: ELQA tests are performed at warm to detect any major defect before cool down in order to intervene in case of need. During the cool down of the machine, some of the circuits have an insulation to ground monitoring. If a fault is detected due to thermal contraction, the cool down might be stop and dedicated diagnostics could be launched. Finally, ELQA tests are performed at cold in order to ensure the readiness and parameters of the circuits before powering test can start. Machine Operation: According to procedure, whenever a cold mass or part of the circuit being cold reaches 80 K, an ELQA test is required. On request, after a powering fault that requires an electrical diagnostic on superconducting circuits. Now that the machine is running, whenever there is a need of a magnet replacement, the type of test that were performed during machine assembly, are adapted, and repeated.

ELQA: Who?...How ? The ELQA tests are performed by trained Engineers and Technicians that have specific knowledge on the electrical measurement and circuit topology. The parameters of the circuits and the criterion applied are predefined and stored in the database. The software allows online validation of the tests. However, engineers are looking at the data and giving furthers analysis or performing additional diagnostics when a fault is detected. Hardware and Software have been developed according to ELQA needs, using components from the industry and adapted to our specificities. The development of the hardware and software is being shared between CERN staff and HNINP (Poland) collaborators. Several application based on LabVIEW have been developed to ensure the quality of the tests. The main goal of ELQA is to ensure qualitative work. Therefore, the ELQA team is focusing on the precision and the quality of the measurements rather than the duration of it. Nevertheless a great effort is put in place in order to stick to the schedule. At the end of the test campaign, the ELQA project engineer validates the test results and finally gives the green light to proceed with powering tests.

ELQA during LS2: always present Time constraint is very tight, see general planning ! Many sectors in different phases in parallel, up to 2 at cold, and more at warm: up to 5 sectors !! The planning for ELQA activities was, and still is very tight! Elqa is present from the very beginning of LS2: Diagnostics at the end of the run, and then Standard ELQA campaign at cold, 2 sectors in // Then present during the consolidation of the LHC at room temperature: replacement of superconducting magnets, Diode insulation consolidation, 11T installation Finally, ELQA team is the last to leave the floor and give the green light for powering test, and then restart of LHC. 5

Summary of ELQA activities during LS2 Elqa@cold before LS2 Non-conformities diagnostics at cold, with powering. TP4-E MIC-C DOC-C NCs solving Warm-up TP4C: Monitoring system of spool and 13kA circuits Elqa@warm before LS2 TP4-A & B MIC-W DOC-W Warm Bus bar measurement ELQA during LS2 Non conformities treatment and Follow-up at warm Diode Insulation Consolidation Magnet replacement: AIV & PAQ. 11 T dipole electrical tests and validation. Elqa@warm before cool-down Elqa during cool-down TP4-C: Monitoring system of spool and 13kA circuits Elqa@cold before powering DC Cables connection NCs during powering tests 2-3 + 10 days 3 weeks 10 days 13 – 16 months 3-4 weeks Circuit diagnostics at cold, before warm-up: following MP3 recommendations Elqa @ cold: serves as reference for the qualification of the circuits at cold, after RUN2, before LS2. Elqa during warm-up: detect eventual fault to ground of the main circuits: thermal expansion Elqa @ warm before massive maintenance: make sure no defect revealed during warm up and as reference for circuit status before massive maintenance. In case of need, there is still time to intervene at warm. Elqa during LS2, at room temperature: Non conformities treatment at warm : re-routing of bus bars, bypass, etc… Follow-up diode insulation consolidation and make sure that the consolidation work do not degrade the circuits integrity, react on the spot! Magnet replacement Consolidation of different measuring system Elqa @ warm after consolidation: qualification of the circuit before cool down Elqa during cool down: detect eventual fault to ground of the main circuits: thermal contraction Elqa @ cold: qualification of the circuits, readiness for powering DC Cable connection 2 teams 2 shifts monitoring 3 teams of 3 pers

ELQA activities at cold, before warm-up Non Conformities diagnostics: 2-3 Sectors in parallel Lockout, measuring system installation, unlockout, Powering tests (measurement), analysis, and need of repetition? 2-3 Field teams performing the test Hardware limitation for many // measurements. Very limited access (ELQA team only). ELQA campaign at cold: 2 Sectors in parallel, 10 days/sector Lockout, and then DC Cables disconnection, galvanic insulation installation ELQA campaign at cold: low voltage and high voltage tests The goal is to verify the integrity of all circuits, including its instrumentation and protective equipment (quench heaters). This campaign should reveal any weaknesses before the warm-up, and serves as a reference at the end of RUN2. Hardware, manpower and coactivity limitation. ELQA fault to ground monitoring during warm-up: 4 Sectors in parallel Monitoring system installation at the end of cold campaign, then remote measurements 7

ELQA activities at warm, during LS2 ELQA campaign at warm + BB segment measurement (TBC): 2 Sectors in parallel, 10 days/sector ELQA campaign at warm: (low voltage and high voltage test), P=6 bar Similar to the ELQA at cold campaign, with adequate parameters. Detect any changes that appeared during the warm-up of the machine. 2-3 Field teams performing the test Hardware, manpower and coactivity limitation. Very limited access (ELQA team only), with some local exceptions Magnet replacement: AIV & PAQ: many sectors in parallel Local tests: (low voltage and high voltage test) About 22 magnets to be replaced (TBC). The goal is to ensure the correct connectivity of the magnet including all the circuits passing through it (Line N, etc…) During the tests, very limited access (ELQA team only). 8

ELQA activities at warm, during LS2 11 T dipole electrical tests and validation: Sector 67 and 78 Electrical test during the 11T dipole installation. Electrical integration verification Coactivity limitation during high voltage tests. Part of the ELQA tests. Non Conformities follow-up at room temperature: all sectors in parallel Follow-up of the Non conformities revealed, analysis, treatment and reporting 2-3 Field teams following the NCs Hardware limitation for many // measurements. Diode Insulation Consolidation: this would include the diode lead measurement and shifted in the day, insulation verification (HV test, like PAQ during LS1). 3-4 Field teams performing the test Local low voltage test with coactivity. Global insulation verification without coactivity and very limited access (ELQA team only, DFBA to DFBA). 9

V Only a sum of all 3 contacts and the copper bus can be measured! Diode Lead Measurement during LS1 All Dipole Diode Leads were measured during LS1: 2464 leads V Only a sum of all 3 contacts and the copper bus can be measured! Courtesy of M. Bednarek 10

Schematics of the DLM set-up (LS1) By moving from magnet to magnet we switch between MBA and MBB lines 3 people are required to move the system smoothly Courtesy of M. Bednarek

DLM Measurement in LS1 Current is applied in steps of 30%, 60%, 80% and 100% of the maximum current value. For reversed mode the max current is 1.5 A. For forward mode the max current is 10 A. Plateau length is 10 s. Linear fit is calculated to get the final resistance value and cancel the offset. Courtesy of M. Bednarek

Diode Lead Measurement during LS2 Before opening of the diode container and after closing the diode container Similar to Diode Lead Measurement during LS1. Local test with possible co-activities. 15 min per magnet 1 sector / week, with one team of 3 persons After consolidation of the diode container, before closing Additional voltage measuring points: (below half-moon connection) Make sure that the consolidation did not influence the diode lead connection Local measurement that would allow the half-moon connection confidence, after consolidation 15 min per magnet 1 sector / week High Voltage tests to qualify the insulation Global insulation verification without coactivity and very limited access (ELQA team only, DFBA to DFBA). High Voltage tests to qualify the insulation: 500 V, 2 min After 17h00, after patrolling the sector Grounding of circuits after test. V V 13

Main MPE - EE activities, during LS2 ELQA @ warm, before cool-down (TP4 A&B) + BB segment measurement (TBC): 2 Sectors in parallel, 10 days/sector similar to ELQA @ warm, after warm-up. ELQA during cool down, (TP4-C): similar to ELQA during warm-up ELQA @ cold (1.9K) end of LS2, before powering (TP4-E): 2 Sectors in parallel, 10 days/sector similar to Elqa @ cold (1.9K) before warm-up Preparation for powering (DQHDS + DC cables connection)

ELQA manpower during LS1 5 CERN Staff + 1 Fellow + 1 FSUs + 25 HNINP Very similar situation during LS2: CERN staff + ~25 P.A. In order to achieve this huge amount of work, we need a lot of qualified and experience manpower: -We were 5 CERN staff + 1 Fellow + 1 FSU and about 25 persons from HNINP.

Hardware and Logistics: 8 TP4s + … Use of 8 existing TP4 measuring systems: used for both standard campaign and diagnostics + 2 AIV systems. Development of additional measuring systems for Diode Lead Measurement Electrical and standard bicycles 12 Pefras, cars allocated to HNINP + TE/MPE car pool To be able to achieve ELQA commitment, we needed substantial hardware and logistics: 8 TP4 measuring systems Additional measuring systems for DLM Use of electrical bikes (4) + about 10 normal bikes 12 Pefras to pull and power the TP4-System Car pool to transport personnel and equipment

Recommendation at CERN: Safety 1st !! Safety aspect… Working in the LHC tunnel, on electrical circuit: Habilitation éléctrique B1, B2 Self Rescue mask course Portable ODH Safety equipment to access the tunnel: bio-cell, helmet, mobile phone, front light, safety shoes, jacket... Grounding of the circuit after ELQA HV Test Recommendation at CERN: Safety 1st !! Working in the LHC tunnel means taking care about safety. For that, whole ELQA team had to follow different safety courses and wear appropriate equipment…. Priority for CERN : Safety 1st, Quality 2nd and Planning 3rd…

Conclusion Detecting and resolving electrical non conformities is our duty and it has been a success so far. Electrical Quality Assurance is mandatory for operating a safe and sound machine. Fruitful collaboration with HNINP based on a long experience and knowledge of LHC. Still a lot of preparation work to be accomplished before LS2, but we are on good track !

Thank you for your attention!