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MP3 meeting
Participants
Adriaan Rijllart
Amalia Ballarino
Andrzej SIEMKO
Antonio Perin
Antonio Vergara Fernandez
Arjan Verweij
Bernhard Auchmann
Christian Giloux
Christine Darve
Gert-Jan Coelingh
Gianluigi Arduini
Giorgio D'Angelo
Glyn Kirby
Howard Pfeffer
Jaromir Ludwin
Jean-Philippe Tock
Jim Strait
Juan Casas-Cubillos
Knud Dahlerup-Petersen
Markus Zerlauth
Mateusz Bednarek
Michele Modena
Mike Koratzinos
Nuria Catalan Lasheras
Odd Oyvind Andreassen
Reiner Denz
Richard Mompo
Rüdiger Schmidt
Sandrine Le Naour
Scheuerlein Christian
Walter Venturini Delsolaro
Zinur Charifoulline
MP3 meeting 2 September 2009
He asked to remind everybody concerned about the procedure to follow.
Walter said he will send an email to the hardware commissioning crews
The modification is easy for the RB, while it is more complicated and requires manufacturing of new elements for the RQs
The work is ongoing and is scheduled to be completed by 19 October
Walter asked whether the unbalances between apertures had been checked against the new di/dt for all sectors
Zinur answered yes, everything should be ok, except maybe some cases in sector 78
Howard Pfeffer said that in case of need the bridges may be re equilibrated for individual boards
Reiner said that it is indeed possible, although it requires an intervention in the tunnel, while for the new QPS it can be done remotely
Walter recalled that last year the problem had been faced by raising the thresholds and said the re equilibration of the bridges, if possible, would be a much better solution
Andrzej said that for the moment the problem concerns only the dipole circuits, not the quadrupoles
Concerning the snubber capacitors Knud will present the subject at one of the next meetings. In any case they are not needed for the 3.5 TeV run.
Amalia asked what are exactly these problems
Antonio answered difficulties of regulation
Gianluigi said ultimately it means that the circuit cannot be powered. In some cases it means that we have to stop the physics run
Nuria added that this also means that the DFB has to be re "consigned"
Antonio said a stock of spares is being built to do the replacements
Gianluigi said that for the incoming sectors (56 and 78) it is already too late to do the replacements without impact on the schedule.
He asked what can be done for the other sectors
Antonio said his team is trying to do this work in the shadow of other activities but it cannot guarantee that this will happen due to lack of resources
Andrzej asked if the problem concerns only the 600 A circuits
Antonio said yes
Nuria commented that indeed so far this is not in the shadow as it has had impact on ELQA
Antonio said that the DFBs are released for ELQA when the level is stable, but this does not mean that all the values are nominal
After a discussion the present agreed that henceforth"release for ELQA" is the same as "release for powering"
Andrzej asked when the procedure for DFB commissioning will be finalized
Antonio answered not before the end of September
Amalia commented that the document is important also because there are special cases and exceptions that need to be handled
Andrzej said he would ask to increase the priority for this procedures
Amalia said that icy lead tops had been reported by ELQA in the tunnel. She stressed that this should trigger an alarm and that somebody should react
Nuria asked who is supposed to react
Antonio said the cryo operators
Nuria asked about the situation of the link of Q4.R1
Amalia said that if the flow had increased by 50% this could mean that the heat load is not normal
Juan Casas Cubillos said that the flow is measured with valves, which is not a good way to measure it
Walter suggested that, still, in relative terms the measure may be meaningful.
Gianluigi asked again about the plans to replace the dirty valves
Ruediger agreed to deal with this in the HCC.
Andrzej asked where the numbers came from
Juan answered they come from geometric calculations and are validated with boil off
Some of these magnets have no temperature reading: there are usually 2 termometers, in 3 magnets both are missing and in other 3 one is missing
MP3 requests that the termometers (sitting in the insulation vacuum) be put back
In the same context Nuria showed a "Timber" plot with the levels in the standalone magnets during ELQA.
Clearly the conditions were far from being stable during the ELQA tests, which of course makes the measurements difficult to interpret
Walter asked whether the ELQA team was aware that boil off tests were ongoing
Giorgio answered no
After some discussion the present agreed that this is a coordination problem that should be dealt with by the HCC.
The measured signals are shared with the QPS. In order to establish the configuration the connector must be unplugged, an action which would trigger the quench heaters
Reiner Denz clarified that the stretch of busbar in question is actually covered by the present QPS system, which has a threshold of 100 mV
An upgraded QPS is as well in the pipeline, which will allow to reduce the threshold and to measure more precisely.
He further informed that D2, D3 and D4 are already covered by the QPS.
Finally Reiner maid it clear that the QPS team cannot support these tests sticking to the present planning. He pointed out that for these measurements QPS needs to be "consigned" and therefore a QPS intervention must be accounted as well.
Richard agreed that (also from the point of view of ELQA) the test is not integrated in the planning
Nuria said the tests are needed in order to coply with the recommendation of measuring all the splices in the machine
Ruediger asked whether the fact of running at 3.5 TeV changes the picture
Nuria answered that it is difficult to say as we don't have any clue on the splices resistances
Reiner said that, to follow the rules, QPS should be recommissioned after the test, because the volatge taps are touched
Andrzej said that the subject should be discussed off line and asked what is the situation for the inner triplets
J. Strait said that the triplet busbars were designed to be self protected. In case of quench the propagation is fast enough to detect it in time for the protection to be effective
He added that the voltage taps configuration allows some degree of inductance compensation, in case one wants to measure the splices
Arjan said that the argument on the triplet busbar protection is exactly the same for the IPQ, which are in this respect very different from the main busbars.
In particular the decay times and the stored energies are incomparable
Andrzej said that it would be useful to have a presentation on the protection of the triplets
Jim agreed to give the presentation at the MP3 meeting in 3 weeks time.
Gianluigi asked what can be done during the next weekend tests
QPS has already planned to switch off the heaters, so it looks possible to make a test
Richard said the software is not yet available
Andrzej said that it is worth getting the equipment installed and make an effort to take data during the weekend
After a suggestion of J. P. Tock, Point 2 was chosen as it gives the possibility of observing "praying splices"
Breakdown happens at 1200 V
the question is whether we can live with this, knowing that the resitance after the test is still very high
Jim Strait said that the internal voltages during quench should be taken into account
The test results presented by Richard do not allow to distinguish between a ground to heater and a heater to coil weakness (only the latter being relevant for the iternal voltages during quench)
Andrzej suggested to perform a coil to quench heater test with the quench heater to ground.
After that we will evaluate if the quench heater can be kept in operation
The magnet should be able to survive with the remaing heaters
Tests done in the lab are relevant as the circuit is designed in such a way that there is no energy sharing between the magnets (Jim Strait)
This will not make the tests less rigorous, but it is just a rearrangement which will increase test efficiency
The proposal was welcomed and endorsed by MP3
General information
Andrzej said that during the HC morning meeting the issue of the coupling between RCO and RCD circuits had been discussed at length.He asked to remind everybody concerned about the procedure to follow.
Walter said he will send an email to the hardware commissioning crews
Summary of extraction time constants for the main circuits (K. Dahlerup Petersen)
Knud showed the values retained for the next run (52 s for the RB and 10 s for the RQF/RQD)The modification is easy for the RB, while it is more complicated and requires manufacturing of new elements for the RQs
The work is ongoing and is scheduled to be completed by 19 October
Walter asked whether the unbalances between apertures had been checked against the new di/dt for all sectors
Zinur answered yes, everything should be ok, except maybe some cases in sector 78
Howard Pfeffer said that in case of need the bridges may be re equilibrated for individual boards
Reiner said that it is indeed possible, although it requires an intervention in the tunnel, while for the new QPS it can be done remotely
Walter recalled that last year the problem had been faced by raising the thresholds and said the re equilibration of the bridges, if possible, would be a much better solution
Andrzej said that for the moment the problem concerns only the dipole circuits, not the quadrupoles
Concerning the snubber capacitors Knud will present the subject at one of the next meetings. In any case they are not needed for the 3.5 TeV run.
DFB boil off summary in sector 12 (A. Perin)
Antonio summarized the tests done on the DFBs in sector 12 , values found were identical to the previous except for DFBAC LCM. A campaign to preventively replace CV891 valves with clean ones is ongoing. This effectively reduces the problems encountered.Amalia asked what are exactly these problems
Antonio answered difficulties of regulation
Gianluigi said ultimately it means that the circuit cannot be powered. In some cases it means that we have to stop the physics run
Nuria added that this also means that the DFB has to be re "consigned"
Antonio said a stock of spares is being built to do the replacements
Gianluigi said that for the incoming sectors (56 and 78) it is already too late to do the replacements without impact on the schedule.
He asked what can be done for the other sectors
Antonio said his team is trying to do this work in the shadow of other activities but it cannot guarantee that this will happen due to lack of resources
Andrzej asked if the problem concerns only the 600 A circuits
Antonio said yes
Nuria commented that indeed so far this is not in the shadow as it has had impact on ELQA
Antonio said that the DFBs are released for ELQA when the level is stable, but this does not mean that all the values are nominal
After a discussion the present agreed that henceforth"release for ELQA" is the same as "release for powering"
Andrzej asked when the procedure for DFB commissioning will be finalized
Antonio answered not before the end of September
Amalia commented that the document is important also because there are special cases and exceptions that need to be handled
Andrzej said he would ask to increase the priority for this procedures
Amalia said that icy lead tops had been reported by ELQA in the tunnel. She stressed that this should trigger an alarm and that somebody should react
Nuria asked who is supposed to react
Antonio said the cryo operators
Nuria asked about the situation of the link of Q4.R1
Amalia said that if the flow had increased by 50% this could mean that the heat load is not normal
Juan Casas Cubillos said that the flow is measured with valves, which is not a good way to measure it
Walter suggested that, still, in relative terms the measure may be meaningful.
Gianluigi asked again about the plans to replace the dirty valves
Ruediger agreed to deal with this in the HCC.
Stand alone magnets (J. Casas Cubillos)
Juan showed the document with the new setting points for the standalone magnets after the consolidation campaign.Andrzej asked where the numbers came from
Juan answered they come from geometric calculations and are validated with boil off
Some of these magnets have no temperature reading: there are usually 2 termometers, in 3 magnets both are missing and in other 3 one is missing
MP3 requests that the termometers (sitting in the insulation vacuum) be put back
In the same context Nuria showed a "Timber" plot with the levels in the standalone magnets during ELQA.
Clearly the conditions were far from being stable during the ELQA tests, which of course makes the measurements difficult to interpret
Walter asked whether the ELQA team was aware that boil off tests were ongoing
Giorgio answered no
After some discussion the present agreed that this is a coordination problem that should be dealt with by the HCC.
Splice measurements in IPQ (R. Mompo)
Richard illustrated the proposed tests to measure the splices in the IPQs. The complete campaign of measurements requires about 36 interventions in the tunnel to install the equipment, and will be managed remotely using dedicate software, which is still under developement.The measured signals are shared with the QPS. In order to establish the configuration the connector must be unplugged, an action which would trigger the quench heaters
Reiner Denz clarified that the stretch of busbar in question is actually covered by the present QPS system, which has a threshold of 100 mV
An upgraded QPS is as well in the pipeline, which will allow to reduce the threshold and to measure more precisely.
He further informed that D2, D3 and D4 are already covered by the QPS.
Finally Reiner maid it clear that the QPS team cannot support these tests sticking to the present planning. He pointed out that for these measurements QPS needs to be "consigned" and therefore a QPS intervention must be accounted as well.
Richard agreed that (also from the point of view of ELQA) the test is not integrated in the planning
Nuria said the tests are needed in order to coply with the recommendation of measuring all the splices in the machine
Ruediger asked whether the fact of running at 3.5 TeV changes the picture
Nuria answered that it is difficult to say as we don't have any clue on the splices resistances
Reiner said that, to follow the rules, QPS should be recommissioned after the test, because the volatge taps are touched
Andrzej said that the subject should be discussed off line and asked what is the situation for the inner triplets
J. Strait said that the triplet busbars were designed to be self protected. In case of quench the propagation is fast enough to detect it in time for the protection to be effective
He added that the voltage taps configuration allows some degree of inductance compensation, in case one wants to measure the splices
Arjan said that the argument on the triplet busbar protection is exactly the same for the IPQ, which are in this respect very different from the main busbars.
In particular the decay times and the stored energies are incomparable
Andrzej said that it would be useful to have a presentation on the protection of the triplets
Jim agreed to give the presentation at the MP3 meeting in 3 weeks time.
Gianluigi asked what can be done during the next weekend tests
QPS has already planned to switch off the heaters, so it looks possible to make a test
Richard said the software is not yet available
Andrzej said that it is worth getting the equipment installed and make an effort to take data during the weekend
After a suggestion of J. P. Tock, Point 2 was chosen as it gives the possibility of observing "praying splices"
ELQA NC on a quench heater in IT R1(R. Mompo)
Richard showed measurements of leakage current that indicate a weakness in one of the quench heaters when tested with respect to the grounded coilBreakdown happens at 1200 V
the question is whether we can live with this, knowing that the resitance after the test is still very high
Jim Strait said that the internal voltages during quench should be taken into account
The test results presented by Richard do not allow to distinguish between a ground to heater and a heater to coil weakness (only the latter being relevant for the iternal voltages during quench)
Andrzej suggested to perform a coil to quench heater test with the quench heater to ground.
After that we will evaluate if the quench heater can be kept in operation
The magnet should be able to survive with the remaing heaters
Tests done in the lab are relevant as the circuit is designed in such a way that there is no energy sharing between the magnets (Jim Strait)
AOB Proposal to stramline PIC tests (M. Zerlauth)
Markus presented a proposal which was worked out by the PIC team to optimize the tests.This will not make the tests less rigorous, but it is just a rearrangement which will increase test efficiency
The proposal was welcomed and endorsed by MP3
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