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MP3 meeting
Participants
Adriaan Rijllart
Andrea Musso
Andrzej SIEMKO
Antonio Perin
Arjan Verweij
Bernhard Auchmann
Christian Giloux
Christine Darve
Fabio Formenti
Gianluigi Arduini
Giorgio D'Angelo
Howard Pfeffer
Jean-Philippe Tock
Knud Dahlerup-Petersen
Laurent Deniau
Markus Zerlauth
Mateusz Bednarek
Michele Modena
Mike Koratzinos
Richard Mompo
Rob van Weelderen
Robert Henry Flora
Sandor Feher
Zinur Charifoulline
MP3 meeting 7 October 2009
The BB are protected with a threshold of 100 mV ; leading to an energy dissipation of 105 MIITS and a temperature of 180 K.
Buses are held in a G10 housing. The connection are soldered and mechanically reinforced by G10 clamps or wrapping of Kapton tape, glass tape and Kevlar string.
The magnet protection mechanism is : Power supply turned off, heater activated and the energy is taken out in a fraction of second.
No bus or splice issue was encountered at FNAL or BNL.
Sandor recommends that no more splice characterization is required.
Andrzej S agreeds on the short term but long term behaviour needs to be monitored.
Arjan reminded that splices are contained in insulating housings.
Gialuigi reminded that for D1-4, the nominal current for this run is 3.5 TeV equivalent and 5 TeV for the inner triplet with the exception of R1 where there is an issue with a quench heater.
Conclusion: MP3 do not judge that splice mapping on D1-45 and the IT during the commissioning for this run is mandatory.
Some measurement are noisy. Zinur proposes to repeat with the second board.
The average resistance is 0.3 nanoOhm. 7 Splices with a possible excess resistance of 1 nanoOhm are identified.
[Out of the meeting, F Bertinelli made a cross check with excess segment measurements NC at 80K : no correspondence identified so far]
As a side subject, Howie P. explained that the difference between board A and B could be linked to the different taps used, with different wiring and position. The difference is not coming from the board itself. This was checked.
This could come from the current flowing through the 100 Ohm damping resistance present in the IFS.
It was tested in the DSL2. The average circuit resistance is about 5.5 nanoOhm.
This value is compatible with the 1 nanoOhm value for one splice, as each circuit contains at least 4 splices.
This type test has demonstrated the feasibility of the mesaurement.
Glyn K. asked what has to be done in terms of (re)commissioning after removal of the system
Knud answered that disconnection needs to be done in collaboration with QPS team and there will be a check by QPS during the relevant IST.
Conclusion: The measurement of IPQs splices was proved possible.
The decision to reduce I_PNO of IPQs (and IPDs) to a 3.5 TeV level is still valid.
Commissioning can proceed without splice mapping.
The system will be left in place DSL2 for reproducibility checks.
Side infrastructure problem: The VDSL connector are sometimes too high in the machine. Extension cables could be installed.
After lifting DFBMC by 20 mm, the problem was solved.
Q4R2 120A correctors:6 NCs were open because they were showing a too high resistance.
A first attempt to solve the problem by lifting the DFBMB of 15 mm was not resolutive;
Also, now the resistance of the Q4 itself is above the treshold of 6 microOhm.
The DFBMB was lifted by an additional 12 mm.
It has to be remeasured by ELQA.
To the question on why there is a change wrt last year, Antonio P. replied that it is likely to be due to small internal movements.
The update on the subject will be presented by ELQA at next MP3.
- I_PNO was reduced last year from 120 A to 80 A
- A step at 70A was added during this commissioning campaign
Values used for this year are at least 5 TeV equivalent
Sandor and Christine proposed to relax the acceptance range for the current lead voltage to : * 85 +/- 30 mV for a nominal current of 80A (5 TeV) and 120 +/- 30 mV for a nominal current of 100A (7 TeV).
The lead is OK up to 150 mV.
The proposal is endorsed by MP3.
The database will be updated and the PNO2 tool will be updated (Adriaan confirmed) with the new values.
It was temporarily repaired for R1. The other DFBXs have to be checked.
A Siemko concluded that this is critical for the magnet protection and so all powering has to be stopped on cold quadrupoles and dipoles of the triplets.
The ELQA team will inspect and eventually fix these connectors. Then the ELQA tests will be repeated.
The test voltage still needs to be defined
Reported by J. P. Tock
Busbars and splices in D1-4 and IT (S Feher)
Sandor presented the busbars of the IT and their electrical insulation.(see slides)The BB are protected with a threshold of 100 mV ; leading to an energy dissipation of 105 MIITS and a temperature of 180 K.
Buses are held in a G10 housing. The connection are soldered and mechanically reinforced by G10 clamps or wrapping of Kapton tape, glass tape and Kevlar string.
The magnet protection mechanism is : Power supply turned off, heater activated and the energy is taken out in a fraction of second.
No bus or splice issue was encountered at FNAL or BNL.
Sandor recommends that no more splice characterization is required.
Andrzej S agreeds on the short term but long term behaviour needs to be monitored.
Arjan reminded that splices are contained in insulating housings.
Gialuigi reminded that for D1-4, the nominal current for this run is 3.5 TeV equivalent and 5 TeV for the inner triplet with the exception of R1 where there is an issue with a quench heater.
Conclusion: MP3 do not judge that splice mapping on D1-45 and the IT during the commissioning for this run is mandatory.
Splice mapping in RB.A78 (Z Charifoulline)
A reduced "pyramid" with 9 flat tops of 10 min each (Ramp rate 10A/s) was applied on RB.A78.Some measurement are noisy. Zinur proposes to repeat with the second board.
The average resistance is 0.3 nanoOhm. 7 Splices with a possible excess resistance of 1 nanoOhm are identified.
[Out of the meeting, F Bertinelli made a cross check with excess segment measurements NC at 80K : no correspondence identified so far]
As a side subject, Howie P. explained that the difference between board A and B could be linked to the different taps used, with different wiring and position. The difference is not coming from the board itself. This was checked.
This could come from the current flowing through the 100 Ohm damping resistance present in the IFS.
Splice measurement of IPQs (R Mompo)
By optimising the parameters for the acquisition, the noise on the measurement was reduced sufficiently to be able to have useful measurements.It was tested in the DSL2. The average circuit resistance is about 5.5 nanoOhm.
This value is compatible with the 1 nanoOhm value for one splice, as each circuit contains at least 4 splices.
This type test has demonstrated the feasibility of the mesaurement.
Glyn K. asked what has to be done in terms of (re)commissioning after removal of the system
Knud answered that disconnection needs to be done in collaboration with QPS team and there will be a check by QPS during the relevant IST.
Conclusion: The measurement of IPQs splices was proved possible.
The decision to reduce I_PNO of IPQs (and IPDs) to a 3.5 TeV level is still valid.
Commissioning can proceed without splice mapping.
The system will be left in place DSL2 for reproducibility checks.
Side infrastructure problem: The VDSL connector are sometimes too high in the machine. Extension cables could be installed.
ELQA on Q4R2 and Q5R2 and their correctors (R Mompo)
Q5R2 120A correctors: they were presenting a too high resistance (> 40 microOhm).After lifting DFBMC by 20 mm, the problem was solved.
Q4R2 120A correctors:6 NCs were open because they were showing a too high resistance.
A first attempt to solve the problem by lifting the DFBMB of 15 mm was not resolutive;
Also, now the resistance of the Q4 itself is above the treshold of 6 microOhm.
The DFBMB was lifted by an additional 12 mm.
It has to be remeasured by ELQA.
To the question on why there is a change wrt last year, Antonio P. replied that it is likely to be due to small internal movements.
The update on the subject will be presented by ELQA at next MP3.
IT 120A correctors (C Darve)
Christine reminded some facts about these circuits:- I_PNO was reduced last year from 120 A to 80 A
- A step at 70A was added during this commissioning campaign
Values used for this year are at least 5 TeV equivalent
Sandor and Christine proposed to relax the acceptance range for the current lead voltage to : * 85 +/- 30 mV for a nominal current of 80A (5 TeV) and 120 +/- 30 mV for a nominal current of 100A (7 TeV).
The lead is OK up to 150 mV.
The proposal is endorsed by MP3.
The database will be updated and the PNO2 tool will be updated (Adriaan confirmed) with the new values.
Q1R1 quench heater (Richard Mompo)
NC 1017471: The warm connectors were checked (Richard and Sandor) and naked conductors were found in the connectors, possibly touching the body.It was temporarily repaired for R1. The other DFBXs have to be checked.
A Siemko concluded that this is critical for the magnet protection and so all powering has to be stopped on cold quadrupoles and dipoles of the triplets.
The ELQA team will inspect and eventually fix these connectors. Then the ELQA tests will be repeated.
The test voltage still needs to be defined
Reported by J. P. Tock
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