MPP meeting

Wednesday 17 Oct 2007, 10:00 → 12:10 Europe/Zurich

30/7-012 (CERN)

Andrzej SIEMKO (CERN AT-MTM)

MPP meeting 17 Oct 2007

General information

The cool-down of sector 4-5 restarted on Friday 12th and the liquid helium phase was reached yesterday 16th at midnight.

Hardware commissioning plan of sector 4-5 (R. Saban, R. Schmidt)

The hardware commissioning will start with the powering sub-sectors at 4.5 K in week 47 after the commissioning of the LSS DFBs. ElQA will take place sequentially in 4R and 5L and after that, the current leads will be connected. Testing of the Individual system tests, QPS setting-up, PCC, PIC and powering to nominal of the circuits will follow as time allows.

Cryo-ok for 1.9 K is expected by the end of week 48 and after that, priority will be given to the 13 kA circuits. PIC1 has been dropped in most circuits but it is kept for the main 13 kA circuits. From the other circuits at 1.9 K a list of priorities will be prepared by MPP. Action: MPP. Depending on a successful powering to nominal of the main arc circuits at the end of 2007, the heat run for all available circuits will be done in week 03/08

S. Russenschuck asked if the deadline to end the power tests in week 03/08 was a hard line. The limit time is coming from the planning so that the inner triplet can be connected, A. Siemko reminded that a second powering campaign is scheduled including the inner triplet. Of course a maximum of circuits need to be commissioned to avoid a second warm-up.

One of the main goals of this commissioning is to have a general quench of the dipole circuit at high current to verify the proper working of the cryogenics.

Report from editors on powering procedures for LHC circuits

• A. Verweij 13 kA circuits:
  
  • RB circut: PCC not yet included waiting from AB/PO. The definition of the MTF steps and the data to be saved needs to be re-discussed. A meeting will be called by Arjan and Mirco by Friday.
  • RQF and RQD circuits: The powering of both circuits can be done separately for PLI1 and PLI2 but has to be don simultaneously from PLI3 onwards. Both circuits are coupled by the QPS system. A failure of the powering in one circuit is possible but it will not harm the hardware. However, they will be some consequences in the magnets magnetization. PCC is completed for these circuit . MTF should be discussed together with RB.
  • G. Kirby asked if A. Ballarino had contributed to the preparation of the documents as she may have some requests on the test/checks to be done on the current leads,
• G. Kirby. Independently powered dipoles:
  • The powering cycle is finished. D. Nisbet is transforming the document to the same format as the 60-120 A circuits. The testing currents for every dipole are specified in the document. The integration of PCC and PIC2 is missing. It should be ready today.
    
• N. Catalan Lasheras Individually powered quadrupoles:
  • As for the previous case, the document is being transformed by HCC in a standard format. Integration of PCC and PIC2 is proceeding ans will be ready tomorrow October 18th. A separate document will provide the list of circuits, test currents and specificities of every sector.
    
• W. Venturini Delsolaro 600 A circuits:
  
  • The draft was circulated yesterday to the authors. PIC2 still need to be discussed in a meeting scheduled for next Friday. The engineering check could be done next week.
• G. D'Angelo 60 and 120 correctors:
  • The document for the 60 A corrector circuits is in engineering check A list of circuits for every sector will be published separately. The document for the 80 A and 120 A dipole correctors will follow.

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1)

Overall status of the Powering Procedures and approval process in EDMS (M. Modena)

A list of the working documents can be found in the AT EDMS tree. Only the 60 A procedure is under engineering check. A powering procedure is missing for the undulator. For the commissioning of sector 4-5, the undulator will not be powered.
The PSQ (squeeze) tests should not be added to the general powering procedures but they should be part of the PAC (Powering of all circuits) test.
R. Wolf suggested that the nested correctors should be tested together even if they have different current rating. A Siemko replied that this should be considered in the simultaneous powering of circuits.
M. Modena requested that the editors add a table of contents to the document.

ElQA issues (S. Russenschuck)

There is a general problem with the routing of the leads inside the DFBX. It can be solved by software.
There seems to be a recurrent problem with the polarity of the warm cables connecting to the 120 A dipole correctors. The extent of the problem is under investigation and may affect other circuits. Action: HCC
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1)

Request from QPS team to open the “30A window” for 600A circuits (W. Venturini)

Experiments were carried out in deliberately manufactured bad splices to state the consequences for the machine of such defaults. Three samples were done with 0.4, 1 and 3 µOhms using a steel layer. The quench limit of the first samples is above 600 A and no signs of overheating are seen.
A splice was done using indium to obtain a 1mOhm splice. When tested, the voltage across the splice increases rapidly with current and stabilizes around 50 A. Following tests showed lower voltages. After the test, the splice presented signs of molten Indium.
Simulations done by A. Werveij using a 100mV threshold showed that the peak temperature stays always bellow 200 K even when the normal zone does not propagate.
It is accepted to go use a 2 V threshold for I<50 A and a 100 mV threshold above this value. This will easy quench detection set-up and commissioning. A post mortem analysis of PCC tests should be done to detect high resistance splices before The PCS step should be kept in a simplified way and should last twenty minutes per circuit.

NCR of MCBY in Q5R4 (N. Catalan Lasheras)

A short -circuit to ground was found in May this year in the RCBYH5.R4B2 circuit (EDMS 842369). The fault was reported to MARIC and MPP in June. (See attached presentation). The short-circuit has been localized right outside the corrector. As it appeared after a serious displacement of the cryostat and the value of the resistance changed after pressure test, it is suspected that the leads of the MCBY have come in contact with the most rigid D4 bus-bars. The circuit has to be re-measured after cool-down but no powering is allowed in the affected aperture.
After warm-up of the sector, the interconnection should be opened and an endoscopy performed in the Q5 side. If the contact is confirmed, a repair in-situ is possible through the M line.
In case that the default can not be repaired, AB/PO is asked to investigate the possibility to run the machine with a floating power converter. Action: AB/PO.

N. Catalan Lasheras
17 October 2007

10:00 → 10:10 General information

Slides MPP_2007_10_17.pdf MPP_2007_10_17.ppt

10:10 → 10:30 Hardware commissioning plan of sector 4-5 (R. Saban/R. Schmidt)

Slides MARIC__071010_rsa.pdf MARIC__071010_rsa.pptx

10:30 → 10:50 Report from editors on Powering Procedures for LHC Circuits

10:50 → 11:00 Overall status of the Powering Procedures and approval process in EDMS (M. Modena)

11:10 → 11:20 ELQA issues (S. Russenschuck)

11:30 → 11:50 Request from QPS team to open the “30A window” for 600A circuits (W. Venturini)

document

• N-Line-Joints.pdf
• QPS_setting_for_600_A_bus.doc
• QPS_setting_for_600_A_bus.pdf

Slides Protection_of_600_A_bus_bars_follow.pdf Protection_of_600_A_bus_bars_follow.ppt

11:50 → 12:00 NCR of MCBY in Q5R4 (N. Catalan Lasheras)

Slides Q5R4_MPP_18062007.pdf Q5R4_MPP_18062007.ppt

12:00 → 12:10 A.O.B.