TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC Reminder: ELQA–Intended Recommendations from the 4 th Splice Review Committee: Prevent unnecessary stressing of the circuit dielectrics of the cold masses During LS1-PAQ voltage withstand testing of the circuit insulation: - Prevent any accidental application of test voltages higher than the specified maximum voltage given by the ELQA TEST PROCEDURE - edms (i.e. 500 VDC) - Instruct the test team never to accept any application of deviations from the test protocol and the applied the parameters Establish an active upper limit to the maximum admissible leakage current - recommended threshold 200  A The humidity of the tunnel air is a parameter to be used for determination of the Hi-potting program of the day LHC Machine Page1 /11

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC Changes Implemented by ELQA after the 4 th Splice Review: I)Hardware and Software voltage limitations were applied to the eight mobile TP4 test stations used for SMACC/LS1-PAQ qualification of the arc circuits undergoing consolidation. - a hardware limit of 600 VDC could immediately be implemented as this feature was already foreseen in concept of the HV generators used in TP4 - a software 500 VDC is now introduced for all Hi-potting from TP4 systems II)A software limit for the leakage current during Hi-potting is now 200  A. When the limit is attained the voltage ramp will automatically stop. III)If the measured tunnel air humidity has reached 55 % or higher ELQA refrains from applying the HV tests on that day. Replaced by a simple short-circuit check at max. 50 VDC. IV)Apart from point above there were no suggestions to change any procedures or methods applied by ELQA during the PAQ or AIV exercises. LHC Machine Page 2/11 TP4 Giorgio in action

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC LHC Machine Page 2/7 Page 3/11

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC Further was decided... To reduce the frequency of the LS1-PAQ tests in each sector from every evening to - twice per week for an ‘active’ sector - once per week for a ‘standby’ sector Reason for this change: - concern over unnecessary stressing of the insulating materials during HV testing - to have sufficient resources to perform PAQ testing in more than 3 sectors simultaneously (the availability of 8 operational TP4 systems will allow this). - to optimize the resources of the section for QPS and ELQA upgrades during rest of LS1 NOTE: There will be no changes to the safety procedures. The paperless condemnation and grounding procedure still requires update of light-panel information in each sector, each evening. This is performed in collaboration CSI-OSM / ELQA. The screen text will be: ‘Sector XY - DFBAs CONDEMNED AND GROUNDED on dd/mm/yy at hh:mm OK FOR SMACC WORK’ and signed - WISH: Only the ‘Ready to install insulation’ approval will now be given by ELQA LHC Machine Page 4 /11

Example of weekly programs: Courtesy G. D’Angelo. Page 5/11

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC State of advancement: S56: On standby, TP4 system maintained at position QEQI.11R5, measurements on Monday evenings, only few IC in open state. S67: Normal program, often high rel. humidity but no particular problems. S78: Normal program, some ‘collateral’ effects from consolidation work (spool shorts), now going better. S81: Just starting up in this sector. TP4 system no. 4 placed at position QQEI.11L1. Reference measurements taken. Short-circuit to ground observed at dipole A30.R8 (diode) during first PAQ tests. Opening of diode box for cleaning recommended. General Observations:  The LS1-PAQ tests are performed on circuits which are under repair, partly open to the air at the IC and equipped with foreign objects and temporary insulation systems.  The main difficulty is to distinguish the signature of a real defect in the permanent circuit components from the signals originating from the temporary equipment and the transitory state (‘collateral effects’).  CONCLUSION: All PAQ measurements performed so far in sectors 56,67 and 78 have revealed no busbar inversions, no wrong polarities, no unexpected busbar ruptures. The appearing dielectric issues could be traced back to ‘collateral’ origins which were eliminated during the continued investigation. LHC Machine Page 6/11

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC LHC Machine Page 7/7 AIV (Arc Interconnect Verification): -Test procedures have been developed by ELQA and INP for N-line interconnect verifications during the interconnection work when a magnet is being replaced. AIV1 and AIV2 are automated Labview procedures for continuity and polarity checks. AIV1: after busbar clamping. AIV2: after busbar US welding. These tests are applied from special AIV test trolleys. -AIV is also applied for circuit integrity verification on the Spool-Piece busbars at this stage. -For the LS1 cryo-magnet replacement program the ELQA tests concern 15 main dipoles. (6 in S12, 3 in S23, 2 in S34, S45 and S78), 3 main quads (all in S34) and Q5L8 -Associated dielectric tests HVQ are applied through partly automated procedures for voltage withstand determination of the various lines. -Special teams of engineers/technicians from HNINP have been trained for this job. Five sectors can be tested simultaneously. Page 7/11

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC LHC Machine Page 8/11 -AIV - Progress obtained so far: -S78: AIV1 and AIV2 successfully completed for the 2 dipoles. -S12: AIV1 performed for all 6 dipoles. AIV2 within the next 2 weeks. -S23: AIV1 completed successfully yesterday on the 3 dipoles (23R2, 25R2, 15L3). AIV2 within the next few days. The two remaining sectors S34 and S45 will follow.

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC LHC Machine Page 9/11 ELQA : Treatment of Circuit Non-Conformities: 35 NC’s were disclosed during the cold and warm ELQA test campaigns earlier this year. 26 of them have been treated by ELQA so far. A large part of these faults is related to cable and instrumentation wire segments. Their nature (high contact resistance, low insulation voltage) are described in a summary table, compiled in the ELQA Database. About 80 % of these NC’s have been closed as origin of failure was found and repaired. All were in the warm part of the instrumentation circuit 2 HV failures could not be reproduced The high wire resistance were in most cases due to poor connections at commercial connectors RCO.A78.B2 and RCO.A81.B2 : Additional measurements have provided more information about the resistive joints (investigation difficult at warm because of copper resistance). Report handed over to MP3. RSS.A34.B1: Grounding fault still under investigation. Further investigation after magnet replacement in the sector.

TE/MPE/EE Short ‘Halfway’ Update ELQA – LS1 Activities MPE/The Electrical Engineering section Knud, on behalf of TE/MPE/EE – 20 September LSC LHC Machine Page 10/11 ELQA: LS1 Upgrade of Proximity Equipment. The upgrade of the 13 kA TT lead sensor circuits began last week with removal from P3 of the first Proximity Equipment cabinet for voltage taps and temp. sensor circuits. The upgrade involves replacement of the failing Canon connectors (300 V withstand!) by the REDEL connectors (3.3 kV). Development of tester completed and available. ELQA will proceed with the corrections of the mid-point inversion on certain 3-conductor IPQ’s (a highly annoying problem for QPS). To be combined with the installation of the new emc-tolerant instrumentation cables for Q8, Q9 and Q10 everywhere in the machine.

TE/MPE/EE ELQA NCR reports and announcements to be issued during LS1 arc consolidation campaign K. Dahlerup-Petersen TE/MPE/EE – 10 July 2012 LHC Machine Thank you Page 11/11