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MP3 report – weeks 21-22-23 20/5/2010 – 09/06/2010

MP3 report – weeks 21-22-23 20/5/2010 – 09/06/2010. MP3/QPS team in CCC. Average of 2.5 actions/ 24 hours Updated 09/06/2010 9h00. RCBX problems. RCBXH1.R2 => Trip on . Known issue related to zero crossing; discrimination time change planned for technical stop.

teagan-mckay
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MP3 report – weeks 21-22-23 20/5/2010 – 09/06/2010

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  1. MP3 report – weeks 21-22-23 20/5/2010 – 09/06/2010 MP3/QPS team in CCC LMC: June 9th 2010

  2. Average of 2.5 actions/ 24 hoursUpdated 09/06/2010 9h00 LMC: June 3rd 2010

  3. RCBX problems. • RCBXH1.R2 => Trip on . Known issue related to zero crossing; discrimination time change planned for technical stop. • Hardware problem found with DQQDG circuit board. Requires change ok for I<50A • Changed on 8th June and ok now • RCBXH1.R1 losses the QPS_ok intermittently since 21 May. Currently masked during injection. LMC: June 3rd 2010

  4. Loss of communication with nQPS crates • 21 May in sector B13.R7 in sector 78 at injection current. Affects RB, RQF/RQD. Power cycle needed before ramping. • Sector 81. Communication lost with B28L8 on 8th June • BB global in sector 67 (rebooted from the tunnel) • Laboratory tests indicate a much smaller failure rate. • It does not seem to affect protection but redundancy is lost. • Still an open issue • RB.A81 => tripped twice: The task to reset the nQPS crate starts while calibration is still ongoing. Calibration should not e done during ramp. Sequencer? LMC: June 3rd 2010

  5. Noisy QPS boards • Trip of sector 6-7 (twice) due to nQPS on RQF; threshold exceeded on B15L7 due to unknown noise. Changed on technical stop. Ok since LMC: June 3rd 2010

  6. Noisy QPS boards • Two trips on Saturday and Sunday due to B25L1 noisy card • Threshold raised on Sunday • Card changed during Tuesday intervention. Running ok Monday Morning Meeting : 3rd of May 2010

  7. Power converter issues • RCBH34.L7B1 => Trip due to DCCT fault. Changed and retested. LMC: June 3rd 2010

  8. 28th of May : 18kV/66kV drop LHC was ramping down (I_RB ≈ 5800 A) As a consequence, all circuits tripped (FPA at 2A/s for the mains) • RB.A45 (MB.B21R4) : heater discharge • RB.A81(MB.C32L1) : heater discharge • MQ.25L1 : Only 1 of 2 heaters fired • Investigation showed that UPS dropped out • Half of the QH and detectors not operational!! LMC: 3rd of June 2010

  9. Technical stop 31 May 1,2 June • New boards for EE switches in all sectors • Tested at 2kA and 6kA in all sectors BUT for 78 (6kA) • RQS discrimination time changed to 190ms all around the ring • Measurement cards in the EE switches. Changed but still problem. Voltage divider Monday Morning Meeting : 3rd of May 2010

  10. Quench heater discharge in Q7.L7 • Triggered by symmetric quench detectors both in RQF and RQD on Monday 7th June • No PM from heater discharge. PM does not allow to understand the squence • Still under investigation Monday Morning Meeting : 3rd of May 2010

  11. RQS.A12B2 • Trips at every reset during the combo • Traced to an open voltage tap in the current lead • Need to be fixed during an access but it is not critical. • Working with board A is ok. Monday Morning Meeting : 3rd of May 2010

  12. Cryo regulation • RD1.R8 • One current lead temperature sensor noisy after the technical stop. • Still there after intervention. • Working ok up to now but it losses Cryo_start and may loss Cryo_maintain. Monday Morning Meeting : 3rd of May 2010

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