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New HV test specification for the LHC

New HV test specification for the LHC . N. Catalan for the EI section. The current specification. EDMS 90327 from 2004 (LHC-PM-ES-0001 rev. 2.0) Refers to equipment tests from manufacturing to installation in LHC Operation conditions define the lower voltage

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New HV test specification for the LHC

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  1. New HV test specification for the LHC N. Catalan for the EI section

  2. The current specification • EDMS 90327 from 2004 (LHC-PM-ES-0001 rev. 2.0) • Refers to equipment tests from manufacturing to installation in LHC • Operation conditions define the lower voltage • Apply decreasing voltages through manufacturing • Only single circuits vs. ground are considered

  3. The voltage to ground for each circuit • Two different sources of voltage during operation • Energy extraction at maximum current U=RI • Quench voltage from simulations • Either/or for all circuits but for dipoles • Safety factor 1.2 applied • Except for dipole circuit • Missing RCO Imax x REE 2xV+500 1.2xV

  4. From ElQA EDMS 788197 (2008)

  5. Insulation tests during TP4-e tests • Different classification from EDMS 90327 • Different tests for air cooled leads • each circuit tested at a lower voltage one by one versus all other circuits and ground. • all circuits of one chimney are tested together at higher voltage level vs ground.

  6. RQ vs Spools • M1/M2 lines and M lines run along together • General protection will run down all of them at the same time

  7. Line N circuits • Bus-bar run together along the same cryogenic line • Metallic braids already gave insulation problems • MQT, MQTL, MQS, MSCB with energy extraction • MO, MQM with no EE Monday Morning Meeting : 3rd of May 2010

  8. Spool busbar routing inside DFBAs Busbars in lines M1 & M2 All 600 A busbars in the same duct Busbars merged with line N Bundles of n x 4 busbars Correctors Spool

  9. New voltage to ground values • Which electrical circuits have bus-bars running in the same cryo-line? • Only circuits whose voltage is coming from EE should be taken into account. • Nested circuits • Maximum operation voltage x1.2

  10. Voltage level proposal • Maximum operational voltage against any neighboring circuit • Tested circuit vs. all others + ground

  11. Practical considerations • HV tests with new voltages need to be implemented prior to cool-down in 2011/2012 • RCO/RCB Lemo connector insulation weakness • Will be inspected in the next technical stop • Repair during the Xmas break? • Tests of the two bus-bars of RQ? • Implemented during the assembly in the long shutdown in 2012 • Is it possible to interrupt the circuit?

  12. MIC tests introduced during 2009 • Magnet instrumentation check • Local measurement at warm and cold • Continuity and resistance of diagnostic Vtaps • Resistance and insulation of QH • QH against coil & ground • ElQA test procedure needs to be updated • Can be done at the same time as HV qualification for the magnet

  13. Quench heaters vs. ground • Not specified in the note • Minimum 2x450+500 = 1400 for most circuits • Voltage on the coil during quench added to this value • Not taken into account in US magnets during manufacturing • Needs to be reviewed

  14. Where is it coming from?

  15. MIC proposed HV values • Tests in SM18 at cold • Reception tests in b181(at warm) for US magnets • Minimum voltage retained • QH/coil vs. ground values?

  16. Conclusions • ElQA test procedure 788197 to be rewritten and reissued • Higher values to be applied almost in all correctors RQ(M) and RQ circuits • MIC test to be added • Hardware modifications in DFB chimneys to remove limitations to be implemented • During Xmas stop • During long shutdown

  17. Xmas break ElQA tests • Machine will be emptied • Three days cooling tower cleaning will stop active cooling on DFBs • All DFBs SAM and SC links will warm up above 120K • According to A. Perin that will mean a full thermal cycle • What parts of ElQA need to be redone?

  18. From ElQA test procedure

  19. ElQA • Only TP4e tests HV in the arc • One week per sector for a team of 2-3 people • Enough resources in house with the eventual help of other sections • Two sectors in parallel. • To be fitted in the schedule • Full TP4e and MIC in the SMA magnets

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