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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

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 3

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 !

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 4

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

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 5

Results:Some MKD Calibration Results

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 6

MKBH Calibration Results

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 7

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

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 8

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

1

2

1

2

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 9

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 !

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 10

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.

0

1000

2000

3000

4000

5000

6000

7000

8000

0 5 10 15 20 25 30

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 11

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

Jan Uythoven, AB /BT LBDS Audit, 28 January 2008 12

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