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MP3 meeting
MP3 meeting 25 November 2009
He then turned to three specific points of more concern for MP3, i.e. the discovered interference between magnets pulsing at the end of the transfer lines and the nQPS; the beam induced 'quench' occurred during threading, and the failing precycles.
Problems emerged during the discussion which followed: nQPS missing signals in the PM make difficult the diagnosis for the MP3 people on shift. As a rule, from the PIC one can see whether the QPS opened the quench loop, and if the old QPS signals do not justify it, one should turn to the nQPS. >br> We need to rediscuss the role of the nQPS: for monitoring or protection?
Arjan pointed out that, once all the splices in the machine are measured, the nQPS interlock will only help in case the resistance of a joint suddenly passes from 0.3 to a few undred nOhm, but WITHOUT OPENING OF THE JOINT, because in the latter case the protection would be in any case ineffective
The role of the old busbar detector was questioned once more, after the discussion in MP3 at the end of July.
As long as the nQPS is not interlocked, it seems enough justified to keep it, despite the inconveniences
The test results were summarized by Sandrine in excel files which will be put in the MP3 sharepoint
Arjan asked whether when analysing the heat run we must select the leads one by one; Sandrine explained that the selection is on a DFB
Notably the RCS circuits finally made it through with the nominal acceleration and didt parameters
On the contrary the RCBX circuits failed due to insufficient compensation of the inductive voltage.
Ruediger Schmidt said that the circuit parameters as commissioned should be gathered in a single spreadsheet
For the quench test in sector 12 the selected magnet (C32R1) had a non conformity on the quench heaters (reconfigured circuit using low field heaters).
Walter asked which list has been used
Gianluigi answered the list in the powering specificities document
Walter reminded we had decided to get a list from the cryogenics colleagues, for quench propagation studies
Antonio Perin confirmed that this is ongoing and will be provided before the next commissioning for the 3.5 TeV run
Outside the meeting Michele Modena checked the heater discharge of magnet C32R1, and found that the circuits are not symmetric. There are some doubts as to whether this is correct
Concerning PGC 1.5 some systematic behavior has been observed in the coupling between 600A circuits powered through the N line.
In particular there is no interference between B1 and B2 circuits
This was also confirmed independently by Ruediger who was looking to the trips occurred during precycles
The behavior is not fully understood as all the busbars run in the N line.
For the heat runs, a number of valves were found to be needing improvements
Amalia Ballarino pointed out the temperatures on top of the DFBX leads will always be higher (60 C were observed), and these should be given priority for installation of interlock switches
After the presentation there was a discussion on why the pre cycling are failing; even after successful PGC.
The pre cycles were specified by the FIDEL team in terms of nominal parameters, and are executed by means of the LSA. Therefore in the pre cycles the magnets are not asked to run at higher than commissioned parameters
The case of lattice sextupoles seems due to insufficient margin on the QPS compensation
Walter made it clear that for the pre cycles of 600A circuits, the ramp rates and accelerations are not critical.
However, reducing the parameters might mean displace to problem to the future
Gianluigi agreed saying that for the moment not all the operational scenarios have been tested
An important point concerns the circuit RCBYHS4.L5B1, which quenches when ramping down from I_PNO.
Giorgio explained that this magnet has a smaller AC transfer function, which might be due to an inter turn short
The magnet is on Yves's list of magnets difficult to control.
It is needed to steer collisions in CMS, and although for the time being the neighbour RCBYH4.L5B1 is used as a spare, Gianluigi explained that ideally the latter should be only used to compensate closed orbit distorsions.
The magnet seems to survive these quenches. Also, it could be operated to a lower current
Nevertheless, a decision must be made before the next long shutdown as to whether to replace it with a warm corrector, as it was done in the past for a similar case.
The familiar PMEA would still be the framework, but now the root will not be the sequencer but rather an event, probably a PIC transition
The problem is how to filter the huge amount of files generated after such an event, selecting those which contain the essential information
This will require some experience and iterations
Odd is currently working on a circuit basis.
This is done with the aim to help answering the question: can this circuit be restarted ?
In the discussion, it was highlighted that the reaction times needed during beam operation are much shorter that those for hardware commissioning
Concerning the mechanism of role attribution, Walter asked how the person to whom a role was attributed will be informed
Odd said that there are many possibilities, including emailing, SMS, automatic phone calls.
It seems reasonable to use emails, as for very urgent cases the operation crew can always call the piquet
One of the tasks that MP3 has to fulfill is checking the correct discharge of all quench heaters before giving green light for re powering.
This job is a good candidate for automatization.
Odd invited everybody to send him feedback on these problems.
First Experience with beam and MP3 (W.Venturini Delsolaro)
Walter gave a brief summary of the milestones achieved so far by the beam commissioningHe then turned to three specific points of more concern for MP3, i.e. the discovered interference between magnets pulsing at the end of the transfer lines and the nQPS; the beam induced 'quench' occurred during threading, and the failing precycles.
Problems emerged during the discussion which followed: nQPS missing signals in the PM make difficult the diagnosis for the MP3 people on shift. As a rule, from the PIC one can see whether the QPS opened the quench loop, and if the old QPS signals do not justify it, one should turn to the nQPS. >br> We need to rediscuss the role of the nQPS: for monitoring or protection?
Arjan pointed out that, once all the splices in the machine are measured, the nQPS interlock will only help in case the resistance of a joint suddenly passes from 0.3 to a few undred nOhm, but WITHOUT OPENING OF THE JOINT, because in the latter case the protection would be in any case ineffective
The role of the old busbar detector was questioned once more, after the discussion in MP3 at the end of July.
As long as the nQPS is not interlocked, it seems enough justified to keep it, despite the inconveniences
Results of PGC (S. Le Naour)
Sandrine presented the results of the PGC tests done so far. Concerning PGC1, the steps 1.3 and 1.6 were skipped; while the heat run (PGC2) was simplified.The test results were summarized by Sandrine in excel files which will be put in the MP3 sharepoint
Arjan asked whether when analysing the heat run we must select the leads one by one; Sandrine explained that the selection is on a DFB
Notably the RCS circuits finally made it through with the nominal acceleration and didt parameters
On the contrary the RCBX circuits failed due to insufficient compensation of the inductive voltage.
Ruediger Schmidt said that the circuit parameters as commissioned should be gathered in a single spreadsheet
For the quench test in sector 12 the selected magnet (C32R1) had a non conformity on the quench heaters (reconfigured circuit using low field heaters).
Walter asked which list has been used
Gianluigi answered the list in the powering specificities document
Walter reminded we had decided to get a list from the cryogenics colleagues, for quench propagation studies
Antonio Perin confirmed that this is ongoing and will be provided before the next commissioning for the 3.5 TeV run
Outside the meeting Michele Modena checked the heater discharge of magnet C32R1, and found that the circuits are not symmetric. There are some doubts as to whether this is correct
Concerning PGC 1.5 some systematic behavior has been observed in the coupling between 600A circuits powered through the N line.
In particular there is no interference between B1 and B2 circuits
This was also confirmed independently by Ruediger who was looking to the trips occurred during precycles
The behavior is not fully understood as all the busbars run in the N line.
For the heat runs, a number of valves were found to be needing improvements
Amalia Ballarino pointed out the temperatures on top of the DFBX leads will always be higher (60 C were observed), and these should be given priority for installation of interlock switches
After the presentation there was a discussion on why the pre cycling are failing; even after successful PGC.
The pre cycles were specified by the FIDEL team in terms of nominal parameters, and are executed by means of the LSA. Therefore in the pre cycles the magnets are not asked to run at higher than commissioned parameters
The case of lattice sextupoles seems due to insufficient margin on the QPS compensation
Walter made it clear that for the pre cycles of 600A circuits, the ramp rates and accelerations are not critical.
However, reducing the parameters might mean displace to problem to the future
Gianluigi agreed saying that for the moment not all the operational scenarios have been tested
Open issues (J.P.Tock)
Jean Philippe went through the list of open issues, which is now much reducedAn important point concerns the circuit RCBYHS4.L5B1, which quenches when ramping down from I_PNO.
Giorgio explained that this magnet has a smaller AC transfer function, which might be due to an inter turn short
The magnet is on Yves's list of magnets difficult to control.
It is needed to steer collisions in CMS, and although for the time being the neighbour RCBYH4.L5B1 is used as a spare, Gianluigi explained that ideally the latter should be only used to compensate closed orbit distorsions.
The magnet seems to survive these quenches. Also, it could be operated to a lower current
Nevertheless, a decision must be made before the next long shutdown as to whether to replace it with a warm corrector, as it was done in the past for a similar case.
PMEA for beam operation (O.O. Andeassen)
Odd presented ideas for new tools that should ease the work of PM analysis during beam operationThe familiar PMEA would still be the framework, but now the root will not be the sequencer but rather an event, probably a PIC transition
The problem is how to filter the huge amount of files generated after such an event, selecting those which contain the essential information
This will require some experience and iterations
Odd is currently working on a circuit basis.
This is done with the aim to help answering the question: can this circuit be restarted ?
In the discussion, it was highlighted that the reaction times needed during beam operation are much shorter that those for hardware commissioning
Concerning the mechanism of role attribution, Walter asked how the person to whom a role was attributed will be informed
Odd said that there are many possibilities, including emailing, SMS, automatic phone calls.
It seems reasonable to use emails, as for very urgent cases the operation crew can always call the piquet
One of the tasks that MP3 has to fulfill is checking the correct discharge of all quench heaters before giving green light for re powering.
This job is a good candidate for automatization.
Odd invited everybody to send him feedback on these problems.
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