MP3 Meeting

Wednesday 17 Feb 2010, 10:00 → 12:00 Europe/Zurich

30/7-012 (CERN)

Nuria Catalan Lasheras

MP3 Meeting (17 Feb 2010)

Present: Nuria Catalan Lasheras; Zinur Charifoulline; Gert-Jan Coelingh; Laurent Deniau; Sandor Feher; Christian Giloux; Mike Koratzinos; Sandrine Le Naour; Edward Nowak; Antonio Perin; Vittorio Remondino; Rüdiger Schmidt; Andrzej SIEMKO; Matteo Solfaroli Camillocci; Jean-Philippe Tock; Marco Zanetti

General Information

Concerning the fault in the circuit RB.A78 mentioned last meeting, this circuit has been qualified only  to 1.6kV for the MBB line. This is deemed to be sufficient for 3.5TeV operation.

N. Catalan informed that a new structurewill take over the QPS diagnosticsbesides MP3 tasks in the CCC after the hardware commissioning. She is still waitig for the final confirmation of the mandate and the members of this team. A. Siemko added that the presence of this team in the CCC will be required at the beginning of beam commissionin a well as in hot periods like increase of luminosity or energy. This could mean the rest of the year.

N. Catalan informed that a test in Block 4 is being organized to investigate the behavior of "sick" RCBY circuits. (see las meeting). One of the eight spares available will be chosen trying to find the worst element. The fault could be reproduced by incresing dI/dt above the machine capabilities.

S12 discharge test on Saturday and implications for PGC.

S. Le Naour presented the event of last Saturday February 13th on which ten magnet quenched during PGC 1.4 test (see slides). The initial fault was provoked by the RSS circuit intentional FPA that was seen by a RQF BB local detectors as a quench. The switches of the RQF and all other main circuits were opened aftar the global protection mechanism was activated. During the EE of the RB circuit, a voltage disturbance was seen by the old  QPS detector of nine magnets in the same electrical line. The tenth magnat was quenched by the nQPS symetric after the other thwo magnets in the family were tripped. 

A large oscillation is seen in the energy extraction resistor voltage in RR17 but not in UA23. Oscillation is not only due to current oscilation times the resistance. Sandrine checked similar tests done during this and past harware commissioning campaigns including quenches on which the current was ramping. The oscillation iin the voltage across the resistance is increasing from 3V to 10V to reach 40V last Saturday. The circuit is now superlocked. A possible fault to graound mentioned by mail bu A. Verweij will be investigated  Action: EPC. he EE team should also go to the tunnel to investigate the current status of the switches.  Action: EE

The threshold of the nQPS will be raised to 500mV as already decided in MP3 last year. This should cure the original fault. Action: R. Denz

AOB

A trip in sector 67 was due to a non standard configuration on the global BB decetor for which only one reference magnet was available. N. Catalan inquired why don't we disconnect the global bus-bar detector. A. Siemko answered that there is the suspiction that two splices are not covered by the nQPS system.  Action: M. Koratzinos

 Nuria Catalan Lasheras and Jean Philippe Tock