LHC Magnets/Splices Consolidation(20 minutes)
Francesco Bertinelli7 June, 2011
23 slides
Status of LHC: electrical connections Description of shunt consolidation Quality Control Scenario for intervention Missing resources
Joint CERN-Pakistan Committee: 6th meeting
LHC electrical interconnections
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W bellows (see
later…)
13 kA (“main”) busbar interconnection splices
From L. Rossi, CERN Courier September 2010
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Poor copper to copper continuity.Provided by butt soldered joints, this electrical quality depends on the:- tolerances of the mating surfaces- relative tolerances between 2 paired bus bars- cleaning of the surfaces- capacity of the soldering to fill the gap providing good contact- correct execution of the soldering.
Lack of internal contact SC cable to bus bar within the same cross-section: partial melting of the Sn-Ag in the bus bar during connection soldering, loss of solder
Need simultaneous presence of two effects:
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2008-09: new Quench Protection nQPS S S S
S S S
EE111 EE112 EE113
EE211EE219
EE119
EE213 EE212
EE015EE014
EE013 EE012R= 100 W
EE111 EE112 EE113
EE211EE219
EE119
EE213 EE212
EE015EE014
EE013 EE012R= 100 W
DC current
MBB line
EE111 EE112 EE113
EE211EE219
EE119
EE213 EE212
EE015EE014
EE013 EE012R= 100 W
MBA line
V
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Our new “eyes” !
LHC main IC splices today (SC)From Z.
Charifoulline
301 ± 85pΩ
Rmax = 2.7nΩRmax = 3.3nΩ
306** ± 313pΩ
(**) number of splices in the quads segments corrected, 1.3 added
Dipole Buses Quad Buses
12 23 34 45 56 67 78 81
Main Dipoles&Quads Bus, sorted by position, 2048 segmentsAll HWC pyramids and plus ~150 ramps to 3.5TeV analyzed
Top 10 Splice Resistances
2nΩ
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Dipole magnets internal splicesFr
om R
. Prin
cipe,
A. Z
aghl
oul,
P. Fe
ssia
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Dipole internal splices today (SC)From Z.
Charifoulline
12 23 34 45 56 67 78 81
12 23 34 45 56 67 78 81
3.1±1.2nΩ8 splices(but not all the same type)
1.4±1.3nΩ3 + 2* splices(* partially)
Main Dipoles
Main Quads
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Cour
tesy
R. F
lora
, C.
Sche
uerle
in
(C17-A17)L2 +36μΩR16→+42μΩ(39.6μΩ, 26.6μΩ)
(C30-A30)L2 +36μΩR16→+29μΩ(41.3μΩ, 12.3μΩ)
(B29-A30)R1 +45μΩR16→+44μΩ
(22.8μΩ, 28.5μΩ, 29.9μΩ)
(B32-A33)R1 +39μΩR16→+53μΩ
(52.3μΩ, 24.9μΩ, 10.8μΩ)
(A18-B17)L2 +35μΩR16→+17μΩ
(28.0μΩ, 11.2μΩ, 13.4μΩ)
Biddle measurements: 1-2 main IC splices (NC)
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The estimated R-8/R-16 random error is ±1 µΩ, and the systematic error is about +10 %.
R8/R16 test: main IC splices (NC)Co
urte
sy C
. Sch
euer
lein
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Shunts on dipole interconnect
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Chosen soldered alloy: Sn60-Pb40 for – Melting temperature (<221.15 Sn-Ag)– Wetting capability– Mechanical and electrical properties
Shunt description
Copper plate 15 mm wide, 3 mm thick.
Copper annealed at 400⁰ C for 2 hours to maximize RRR
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Total magnet to magnet interconnects in the machine: 1 688
Total 13 kA splices: ~10 200 Number of splices to be redone: ~1 500
(15%) Number of shunts to be applied: ~27
000
Shunt work in numbers
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Copper surface machining
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The shunt soldering process
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Isostatic assemblyMirror symmetry across H and V planes (assembly facilitate and cost saving)Allowed misalignment default V±5 mm, H±3 mmSecond insulation skin Pre-stress adjusted with accurate tooling (5kg)Helium ducts in order to give good cooling for the bus bars (no thermal barrier)
1) Shunt soldering in position2) Central insulation piece introduction between the bus bars3) Lateral insulation pieces introduction4) Polyimide foil wrapping around insulation pieces5) 316L collars tie clamping around
Insulation box and assembly procedure MB
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Quality Control of main IC splices R_RT-top-side tests for the QC of individual
solder contacts. After repair the shunt contact on the wedge
of M3-QRL-connection, R_RT-top-side is reduced from 10.5 µΩ to 2.1 µΩ.
Comsol R_RT-top-side simulation for shunt with defect (courtesy S. Heck)
R_RT-top-side measurement configuration
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Examples of damaged cables found in 2009 by the personnel performing the interconnection work
NCR 1002739: Entire cable squeezed between U-piece and wedge
NCR 990852, 2 strands cutNCR 992513: Cable overheated (>580 °C)
NCR 1002739: Entire cable was squeezed between U-piece and wedge 18
i.e. important to have experienced technicians,
specifically for the most critical activities
What activities are involved for IC work?
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Orbital machining to cut open TIG welds
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Duration of IC work at 50 IC/week (!!!) for critical activities, 14 weeks for 1st sector, 5 weeks later for 2nd sector, 49
weeks for 8 sectors 2 shift work (on different activities), some overlap:
• 6h–10h/break/11h-15h• 12h-16h/break/17h-21h
no learning curve, no built-in contingency, no account for holiday/closure periods
must work sequentially to adjacent sector, without access constraints (i.e. first cool-down and HWC powering)
big concern is the “other activities” to be done in parallel: more realistic is to consider an additional 2-3 months 21
Estimate of IC resources needed
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ActivityIdentified,
trainedIdentified, but need training
Missing resources
Comment
Opening and closing W 8 20 TE-MSC-MNC, FSUs task oriented, Dubna Project Associates
Bellows inspection & protection, endoscopy beamlines 5 3 TE-VSC, Krakow Project Associates
Repair, reinstall & tack PIMs incl. 2 TE-VSC, FSUs
Orbital machining M sleeves and PIMs 3 3 5 FSUs
Busbar copper surfacing machining 7 TE-MSC-MNC
Electrical connections 8 9 3 FSUs, further CERN contribution?
QC electrical connections 4 14 TE-MSC-SCD, BE-OP
ELQA 13 10 Krakow Project Associates
Leak testing 12 7 AL 40-30 (S133 contract)
TIG welding M sleeves and PIMs 6 9 EN-MME and S142 contract
QC Welding 2 4 EN-MME, external contract, BE-OP
QC closing W 4 TE-MSC-MNC, BE-OP
Other 5 5 logistics, coordination, overall QA: further CERN contribution?
DN200 7 1 Dubna Project Associates
Special Intervention IC Team 7 4 9 TE-EPC, FSUs, further CERN contribution?
Total 70 72 57
Note: resources at peak
QPS 9 7 Krakow Project Associates
199
Pakistan Collaboration?
The current scenario
1 “train” only for standard activities A Special Intervention team to prepare non-
standard work before the arrival of the train Long Shutdown starting January (April?) 2013 [email protected] to replace F. Bertinelli
as IC&Magnet Long Shutdown Project Responsible starting 1 July, 2011
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