Wrap-up of hardware commissioning 2011
Andrea Musso
Arjan Verweij
Cedric Charrondiere
Edward Nowak
Giorgio D'Angelo
Grzegorz Seweryn
Hugues Thiesen
Jean-Philippe Tock
Jens Steckert
Kevin Priestnall
Knud Dahlerup-Petersen
Manuel Angel Dominguez Martinez
Markus Zerlauth
Matteo Solfaroli Camillocci
Michele Modena
Mike Koratzinos
Nuria Catalan Lasheras
Rüdiger Schmidt
Sandrine Le Naour
Stephen Pemberton
Zinur Charifoulline
Wrap-up of hardware commissioning 2011 (08 Mar 2011)
http://indico.cern.ch/conferenceDisplay.py?confId=129805
Present: Nuria Catalan Lasheras; Zinur Charifoulline; Cedric Charrondiere; Giorgio D'Angelo; Knud Dahlerup-Petersen; Manuel Angel Dominguez Martinez; Mike Koratzinos; Sandrine Le Naour; Michele Modena; Andrea Musso; Edward Nowak; Stephen Pemberton; Kevin Priestnall; Rüdiger Schmidt; Grzegorz Seweryn; Matteo Solfaroli Camillocci; Jens Steckert; Hugues Thiesen; Jean-Philippe Tock; Arjan Verweij; Markus Zerlauth
600 A circuits resistance measurements.
During the PCS analysis, the wrong value of resistance was sent to MTF (R45 instead of RPNO). Cedric will look at the bug. A list with all results can be generated later (Action: Cedric) and updated in MTF. MP3-CCC members are reminded that the PNO.a3 test has to be signed using the PCS tools so that the values are sent to MTF. We need to find a way to enforce that the test is signed properly. This should be the case for all tests. (Action: Markus and Cedric)
Once the data is cleaned, only MQTL11. R2B2 seems to remain as an outlier. The circuit was measured once in 2008 and once in 2011. Resistance from last campaign was inside tolerance. The test should be repeated at least once, and if the value is confirmed, a NC should be open and test should be carried in the tunnel. (Action: Edward and ELQA)
Mike noticed that the resistance is always positive. If it is indeed noise, it should have both signs. The calculation is done by taking absolute value.
The number of splices in a circuit used by he PCS tool is wrong due to the assumptions that the interconnection splices are identical for circuits for a given family. The tolerance per splice is currently the same for all kinds of circuits. It is proposed to put a tolerance only on the total voltage across the circuit and not in the individual splice resistance. (Action: Edward). The PCS tool will be modified accordingly and will also include the voltage across the current leads. It is proposed that the PNO.a3 is kept but its analysis will be adapted to the findings.(Action: Cedric)
RQT13.L7B1 NC and electrical measurements.
Excessive resistance was seen in MQT13.L7B1 after PNO.A3 test. The circuit was measured four times with both QPS cards. An ElQA team measured the circuit in the tunnel using PXIs. As a first observation, a high noise is produced by the converter. Knud suggested using another current source with low noiseeven at low current. ElQA is already using its own PC inside TP4 to do the ELQA resistance measurement but it does not seem to be enough.
The number of splices in the MQT typre circuits was recalculated and does not match the number in the PCS tool. This needs to be recalculated for each LHC and serve as an input also for the schematic drawings. (Action Markus, Mateusz, Jean Philippe, Stephen)
As a conclusion, QPS resolution does not alow for nOhm measurements. Udiff resolution seems to be 5mV from Timber but it is indeed better than that, Zinur added that U_res is calculated analogically. The resolution of U_diff and U_res signal for every circuit type needs to be clarified. (Action: Zinur)
It is proposed to measure all the 600A circuits once n the tunnel before the long shutdown. We need to evaluate the time and resources needed to measure all 600A circuits. (Action: Mateusz)
The type measurment done on the RCS.A45B1 was presented. The aim of the test was to measure the resistance of circuits segments. Very good results. Promising to even distinguish between internal and interconnection splices.
RCO.A45B1 NC and quench-like event.
The issue was presented to acquire knowledge about the signature of the default. Tightening of the screws has not been verified everywhere and may happen in other circuits. See Markus presentation
Current leads regulation during PGC
Sandrine has done an analysis of the heat runs of last campaign by looking at the maximum excursion f the TT891A temperature sensor. During the heat run of 18th Feb one type A, two type B and two types C leads were found not optimal even if the temperature stayed inside tolerances. There were no other cases found during the heat run of 19th Feb.
The temperatures swing in the DFBX is more important during transients but more stable during the flat-top.
In general, the regulation of temperature is now much better than in the past and it should improve in the near future when all 600A valves will be changed by the new mode.
As the analysis of this type of behavior may be necessary during operation, we need to verify if CRG is looking at the signals periodically and use the same kind of alarms we are using. (Action: Sandrine). After the meeting, CRG was contacted and confirmed that a similar monitoring is done by them and that the defective circuits had already been identified. The MP3 tests will be thus done only during hardware commissioning campaigns.
PNO analysis tool and NCs.
Analysis of the failing modes. In the rare case when U_lead values are over threshold, there is probably a problem with the converter. We should fail the test and forward the test to EPC.
If the fault comes from R_magnet magnets, measurements in the machine shal be done. The resistance of the warm cables has a large influence in the calculation and if wrong should be corrected in the database and the test re-anayzed. A large number of circuits were measured by EPC in the 2009 campaign. An updated list was presented by Giorgio on the next day with the suspected cases and actions. In most cases, verification in the tunnel is proposed for the next technical stop. (Action: EPC and ELQA) A NC will be open for every case and should be commented after the technical stop (Action: Giorgio)
The resistance of a magnet is calculated only from the positive plateau and again from the negative plateau. It is proposed to calculate the resistance using a fit of both plateaus. This will eliminate some of the magnets out of range (Action: Cedric)
Orbit correctors trips during PGC
The status of not clear all. A summary table should be presented the suspected magnets, resuming the resistance value their previous history, if measurements in the tunnel. (Action: Michele. done for the next meeting)
RSS.A78B1 quench-like events during PGC
This event, as for the RCO.A45B1 was seen as a QPS trip. It was indeed a connection issue inside teh power converter.
These kind of faults has not been seen during last years. It seems then to evolve with time. The signature is also similar to some of the orbit dipole correctors seen in the previous presentation, which could indicate a tightening problem.
A proposal exists done by Y. Thurel on testing this fault in all the machine by monitoring the V_meas and I_ERR after relaxing the control loop. Hugues suggested making the same check without modification of the loops. A procedure for test should be written by EPC in order to be implemented at the next technical stop. It should consider measuring also the dipole orbit correctors. (action: Hugues)
RQ6.L3B2 and RQ6.R7B2 quenches after commissioning
The magnet only quenches at high current while it is used at 150A. A NC should be open to remember its specificity during the next hardware commissioning. (Action: Andrea)
RQTL9.L7B1 quenches after commissioning
The magnet has indeed tripped four times in 2008, twce in 2009 and twice in 2011. The signature is very similar in all cases but in some of them, the number of points above QPS threshold does not justify the trigger. Board B is as usual blamed. A NC should be open (Action: Jean Philippe). As a preventive measure, the power module will be changed during the next technical stop (Action: Hugues) and the monitoring board changed to board B (Action; Knud) to try to catch the fault.