1 lbds testing before operation jan uythoven (ab/bt) based on the work of many people in the ksl, ec...
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LBDS Testing Before Operation
Jan Uythoven (AB/BT)
Based on the work of many people in the KSL, EC and TL sections
Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 2
Outline
MKD and MKB Systems Testing before installation
Calibration in the laboratory Testing in the machine
Calibration Reliability run
Testing of the complete LBDS System From local operation to running the complete
system from the CCC Conclusions
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Calibration in the Laboratory before Installation
MKD:2 x 15 Magnets2 x 15 Generators+ 2 x 2 Spares MKBH: 2 x 6 2
MKBV: 2 x 4 230 metal coated ceramic chambers: partly calibrated!
Inductive field probe !
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Why Calibration?MKD and MKB Systems
Calibration of individual components Test all magnets with the same reference generator Test all the generators with the same reference magnet Test some of the ceramic chambers (different resistance of the coating) on the
same magnet and the same generator Determine the relation between measured field and current Precise measurements of the magnet and generator performance gives:
Quality assurance Find the “bad” magnets / generators and fix them, measure again and see if its
better Weak components were detected and replaced during the calibration process
Critical parameters determined Method for the analysis of current waveforms developed
Later used by IPOC and XPOC Comparison with specification / design
Just ok on rise time and overshoot For MKD determination of individual trigger voltages as function of ‘beam
energy’ Necessity ‘discovered’ during the calibration process
Used for sorting and assigning equipment positions in the LHC
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Results:Some MKD Calibration Results
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MKBH Calibration Results
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Measurements once installed in Tunnel
Repeat same calibration measurements in tunnel Comparison of Reference Measurements Example for measured Pulse Length
Typical MKD generatorPulse length comparison calibration hall and two measurements in tunnel
Measurement of pulse which is too short and continues to become shorter: Compensation capacitor replaced
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Results XPOC over Several Weeks of Running (25/11/07 to 12/01/08)
15 MKD systems, beam 1, at 2 TeV
Downwards trend on Amplitude not understood
Pearson transformer Hysteresis Comm. of
Rogowski trans. Capacitors Temperature effects
Pulse length: replaced capacitors
100 % point, relative [%]
End point, after 91 s [%]Overshoot 2 [%]
OverShoot 1 [%]
Compensation capacitor replaced
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Reliability Run
A testing policy can be applied to 2x15 MKD generator branches per LBDS, 60 in total, in order to accept or reject the hypothesis that they are SIL3 at least.
The test considers the branch failures only and not the system failure. A test of three months with 1 hour missions ensures that the system is SIL3 or
better at 95% confidence level if less than 6 generator branch failures are observed.
MKD SIL3
Decision threshold
Failures for a 3 months test
10-4 is the assumed failure rate of one generator branch in order that MKD system is SIL3
Failure rate
Observed failures
Started running in November
So far no failures detected !
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Energies Used during Reliability Run
Philosophy is 12 hours stable at 7 TeV settings followed by one pulse, and series of 5 pulses at different energies (average ~ 1/hour).
Always following realistic ramp rates.
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1000
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0 5 10 15 20 25 30
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System Commissioning
Connect up to non MKD – MKB equipment. Add equipment when they become available Timing – Beam Interlock System (BIS)
To be done in the coming weeks, as LBDS – BIS is a safety critical link Close BIS loop locally in point 6
MSD: ramp synchronously with MKD/MKB TCDQ: position to follow ramp Beam Instrumentation (XPOC) RF (synchronisation) Q4 – possibly run in short circuit when magnet not cold Main dipoles for BEM: connect when cold and available
Once connected up to the BIS, running from the LHC Control Room Test as much of the equipment as possible Operator experience with the LBDS equipment
First tests to start in two weeks
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Conclusions
For the MKD and MKB systems standard, precise measurements have been made before installation and, once installed, during ’continuous’ pulsing They have been successfully used to detect weak components
during initial testing and also for one generator once installed They will also be used for the IPOC and XPOC analysis
Today, the systems have been pulsing for several weeks as part of the reliability run No failures detected so far. Would expect about two failures on
the switches, according to dependability model. Some trends are observed which are not yet fully understood
No risk to safety, as trends are slow and captured by the pulse analysis
Reliability run ongoing for the coming months, in parallel with other works
System commissioning starting in two weeks