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MP3 meeting
Participants
MP3 meeting 24 June 2009
Matters arising
Nuria informed that she had attended the TEMB (group leaders meeting of the TE department) last Monday.
Therein it was made clear to her that the responsibility to approve the calorimetry step is with the CRG group.
Serge Claudet will provide the indicators for a quick "stop/go ahead" after the test, and Laurent Tavian will deliver the estimated values of the resistances in 24 hs
J. Strait is working on a systematic comparison between the results of the two existing tools.
He went through all the circuit types trying to identify where to put the splitting line.
The presentation gave rise to a few comments and proposals:
Sandrine asked why the 600 A would be limited to 200 A only in sector 34
Gianluigi answered that in sector 34 we expect more problems as most circuits are new.
Walter and Arjan suggested to move the line for the main circuits (RB/RQF/RQD) after the first test at 5 kA. This would bring a detailed picture of the splices before the stop, and reinforce the motivation of a staged approach being more effective, as analysis and tests run in parallel for hardware and beam
J. Strait noticed that in case of inavailability of one or more sectors it might be interesting to switch back to HC.
Gianluigi said that in this case we should then go to the end (of HC).
Nuria asked what kind of PCG tests are required in the staged approach.
Gianluigi said PGC would be limited at testing the operational cycle.
Bob suggested to incorporate the PCG in the beam commissioning.
Nuria asked if the cohabitation of ElQA and QPS activities with beam operation will be an issue. The answer is not for ElQA because it is supposed to be finished by then. It could be a problem for QPS
To be noted that in case of problems with the symmetric quench detection, the initial beam commissioning below 1 TeV could still be done.
Furthermore, the hardware commissioning of the RB circuits may still be done at 5 kA, as the symmetric quench detection is only needed above 7 kA Report from the CCC (M. Bajko)
Marta reported the activities in the CCC last week, most tests were on 60 A circuits and went smoothly, with the exception of two circuits, which quenched 3 times: one was a training quench, while in two cases the magnet quenched on the flat top after 11 an 55 seconds respectively. The reality of the quench was confirmed by the time constant of the current discharge and by the observation of a temperature hump in the He bath.
The current leads were checked and found ok (they were not the origin of the quench).
The test was repeated at 40A, with no quench, and then at nominal (55A), this time successfully.
The interpretation of such quenches on the flat top is not entirely clear
It seems that they might happen after relatively long times (4' 30" in one case)
Arjan said that the flat top time should be increased.
Rudiger reminded that we don't need all these circuits at 55 A, but most of them are now commissioned at 55 A with the present procedure.
He said increasing the flat top time should be done only in problematic cases
Andrzej said that last year we had no problem whatsoever with these circuits and that it was better not to create exceptions
Marta said that the procedures need to be more explicit concerning the off line analysis done by MP3
For example, the procedure do not say where to find the current lead signals, or how to handle situations like the one just described.
Also some parameters found in the tools are not mentioned in the procedures.
Andrzej welcomed Marta's observations and said that this needs the feedback of the new users, as not everything can be foreseen by the authors of the procedures
ACTION –> Giorgio will add a paragraph in the 60 A procedures detailing how to check the lead signals
Nuria said that we will start to have meetings with the ccc crew to train newcomers.
AOB
Walter reported briefly on the issue of DFBX current leads: this has resurfaced recently when it was realized that the 120 A circuits of the triplet were being analysed with the tool used for the 60 A (PNO2)
The resistive leads of the DFBX however, are totally different in design form the conduction cooled leads of the 60 A circuits.
They are actively cooled and the control loop is based on a temperature sensor which reacts with minutes delay to temperature changes. The operation is then characterised by oscillations, to which the PNO2 tool is not adapted.
Actions are ongoing to solve the immediate problem of step approval: Giorgio has already modified the procedure to include this exception, and Christine Darve is working on tolerances.
In the meanwhile it was confirmed by S. Feher that the protection threshold of 160 mv is safe, even though the leads operate well above optimum (at 140 mV).
Sandor recalled in his email that the possibility of using the lead voltage as controlled variable should have been studied last year by A. Perin.
Andrzej commented that last year the problem arised because these leads should work with a flowmeter, which was not available.
He added that the voltage regulation had been declared unfeasible last year.
He nevertheless conceded that we should revist this.
Walter said that the voltage regulation would probably inprove the oscillations, by removing the delay in the control loop
Richard Mompo showed the results of leakage current measurements between quench heaters and coil, and between coil and ground in dipole 2313 (sector 12). the values are one order of magnitude higher than normal.
It was decided to stop the cool down of the sector which was planned for today, and launch in parallel an investigation. In particular, the LF heaters should be discharged and new measurements of the leakage current be done.
In addition the insulation between coil and ground should be carefully tested, as there might be a fault through the HF circuits.
Topics for the next meeting:
IT procedures, and excepions (to fire or not to fire?)
PGC procedure
DFB commissioning procedures (A. Perin)
Visibility of NC in the layout DB
Matters arising
Nuria informed that she had attended the TEMB (group leaders meeting of the TE department) last Monday. Therein it was made clear to her that the responsibility to approve the calorimetry step is with the CRG group.
Serge Claudet will provide the indicators for a quick "stop/go ahead" after the test, and Laurent Tavian will deliver the estimated values of the resistances in 24 hs
J. Strait is working on a systematic comparison between the results of the two existing tools.
Minutes of the last meeting
There were no additional comments on the minutes of the last meeting.Interleaved HC and Beam commissioning (G. Arduini)
Gianluigi presented a detailed proposal for carrying out the hardware commissioning in two stages, with in between a period of beam commissioning up to maximum 1 TeV. (Slides).He went through all the circuit types trying to identify where to put the splitting line.
The presentation gave rise to a few comments and proposals:
Sandrine asked why the 600 A would be limited to 200 A only in sector 34
Gianluigi answered that in sector 34 we expect more problems as most circuits are new.
Walter and Arjan suggested to move the line for the main circuits (RB/RQF/RQD) after the first test at 5 kA. This would bring a detailed picture of the splices before the stop, and reinforce the motivation of a staged approach being more effective, as analysis and tests run in parallel for hardware and beam
J. Strait noticed that in case of inavailability of one or more sectors it might be interesting to switch back to HC.
Gianluigi said that in this case we should then go to the end (of HC).
Nuria asked what kind of PCG tests are required in the staged approach.
Gianluigi said PGC would be limited at testing the operational cycle.
Bob suggested to incorporate the PCG in the beam commissioning.
Nuria asked if the cohabitation of ElQA and QPS activities with beam operation will be an issue. The answer is not for ElQA because it is supposed to be finished by then. It could be a problem for QPS
To be noted that in case of problems with the symmetric quench detection, the initial beam commissioning below 1 TeV could still be done.
Furthermore, the hardware commissioning of the RB circuits may still be done at 5 kA, as the symmetric quench detection is only needed above 7 kA
Report from the CCC (M. Bajko)
Marta reported the activities in the CCC last week, most tests were on 60 A circuits and went smoothly, with the exception of two circuits, which quenched 3 times: one was a training quench, while in two cases the magnet quenched on the flat top after 11 an 55 seconds respectively. The reality of the quench was confirmed by the time constant of the current discharge and by the observation of a temperature hump in the He bath. The current leads were checked and found ok (they were not the origin of the quench).
The test was repeated at 40A, with no quench, and then at nominal (55A), this time successfully.
The interpretation of such quenches on the flat top is not entirely clear
It seems that they might happen after relatively long times (4' 30" in one case)
Arjan said that the flat top time should be increased.
Rudiger reminded that we don't need all these circuits at 55 A, but most of them are now commissioned at 55 A with the present procedure.
He said increasing the flat top time should be done only in problematic cases
Andrzej said that last year we had no problem whatsoever with these circuits and that it was better not to create exceptions
Marta said that the procedures need to be more explicit concerning the off line analysis done by MP3
For example, the procedure do not say where to find the current lead signals, or how to handle situations like the one just described.
Also some parameters found in the tools are not mentioned in the procedures.
Andrzej welcomed Marta's observations and said that this needs the feedback of the new users, as not everything can be foreseen by the authors of the procedures
ACTION –> Giorgio will add a paragraph in the 60 A procedures detailing how to check the lead signals
Nuria said that we will start to have meetings with the ccc crew to train newcomers.
AOB
Walter reported briefly on the issue of DFBX current leads: this has resurfaced recently when it was realized that the 120 A circuits of the triplet were being analysed with the tool used for the 60 A (PNO2)
The resistive leads of the DFBX however, are totally different in design form the conduction cooled leads of the 60 A circuits.
They are actively cooled and the control loop is based on a temperature sensor which reacts with minutes delay to temperature changes. The operation is then characterised by oscillations, to which the PNO2 tool is not adapted.
Actions are ongoing to solve the immediate problem of step approval: Giorgio has already modified the procedure to include this exception, and Christine Darve is working on tolerances.
In the meanwhile it was confirmed by S. Feher that the protection threshold of 160 mv is safe, even though the leads operate well above optimum (at 140 mV).
Sandor recalled in his email that the possibility of using the lead voltage as controlled variable should have been studied last year by A. Perin.
Andrzej commented that last year the problem arised because these leads should work with a flowmeter, which was not available.
He added that the voltage regulation had been declared unfeasible last year.
He nevertheless conceded that we should revist this.
Walter said that the voltage regulation would probably inprove the oscillations, by removing the delay in the control loop
Richard Mompo showed the results of leakage current measurements between quench heaters and coil, and between coil and ground in dipole 2313 (sector 12). the values are one order of magnitude higher than normal.
It was decided to stop the cool down of the sector which was planned for today, and launch in parallel an investigation. In particular, the LF heaters should be discharged and new measurements of the leakage current be done.
In addition the insulation between coil and ground should be carefully tested, as there might be a fault through the HF circuits.
Topics for the next meeting:
IT procedures, and excepions (to fire or not to fire?)
PGC procedure
DFB commissioning procedures (A. Perin)
Visibility of NC in the layout DB
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