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MPP meeting
MPP meeting (13 Feb 2008)
Present: Nuria Catalan Lasheras; Mari-Paz Casas-Lino; Lyn Evans; Sandor Feher; Carlos Fernandez Robles; Robert Henry Flora; Anne Funken; Thiesen Hugues; Mikko Karppinen; Mike Lamont; Sandrine Le Naour; Solfaroli Camillocci Matteo; Karl Hubert Mess; Mirko Pojer; R. Saban; Rüdiger Schmidt; Andrzej Siemko; Walter Venturini Delsolaro; Antonio Vergara Fernandez; Arjan Verweij; Rob Wolf
Chaired by: Dr. Siemko, Andrzej
To protect the circuit in case of quench of any magnet, additional paths for the current have been provided by adding free wheeling diodes and a thyristor. The current decay after a fast power abort in all three power converters ranges from 100 to 430 s making it the longest decay in the LHC (QF/QD are about 400s). The diodes and thyristor are water cooled but in the event of a water cooling fault, the heat during the discharge could damage the free wheeling diodes The present solution consist on firing the quench heaters when a water fault is detected. This is not acceptable from the point of view of the magnets. As a short term solution, It is proposed to fire the quench heaters only if one of the PC is above 3kA. A delay will also be added before the quench heaters are fired. In the long term (six months), a thermal couple will be installed in the leads and the heaters will only be fired if the temperature is too high. It is estimated that, after the implementation, the quench heaters will be fired due to a water fault once in the life time of the inner triplet. Both solutions do not imply any modification of the PIC. MPP endorsed the proposal and required that the short term solution is implemented before the first powering of the inner triplet. Action AB/PO
S. Feher presented in detail the magnets in the inner triplet and the relevant issues for the powering tests (see slides).
The cryogenic control of the power leads requires controlling the flow rate in the 600 A leads. This will be addressed in a future meeting. Action CPP.
The quench performance of these magnets implicates few or no training quenches up to nominal current. The polarity of the current leads in the DFBX has been recently found incorrect. Fermilab has worked together with the ElQA team to solve the problem and relabel the current leads but this numbering does not correspond to the one used by the QPS system. Action: Mr. Polarity and QPS team.
Quench signals as measured in KEK and Fermilab were shown. The parameters of the quench heaters tested in KEK are not knwon. Action: S. Feher
The reasons for the fragility of the quench heater wires in the LHC magnets and where we can found problems will be the subject of a future presentation. Action: G. Kirby.
The powering procedure for the inner triplet will be circulated for approval as soon as possible as powering could take place in week 12. Action: editors. The powering procedure for the correctors will be prepared separately. Action editors plus W. Venturini Delsolaro and R. Wolf.
For these tests the main circuits are defined as RB, RQD, RQF and the 6 kA individually powered quadrupoles (Q7-Q10 in both sides of the arc).
The remaining issues are postponed due to lack of time.
Last updated on 13 February by N. Catalan Lasheras
Present: Nuria Catalan Lasheras; Mari-Paz Casas-Lino; Lyn Evans; Sandor Feher; Carlos Fernandez Robles; Robert Henry Flora; Anne Funken; Thiesen Hugues; Mikko Karppinen; Mike Lamont; Sandrine Le Naour; Solfaroli Camillocci Matteo; Karl Hubert Mess; Mirko Pojer; R. Saban; Rüdiger Schmidt; Andrzej Siemko; Walter Venturini Delsolaro; Antonio Vergara Fernandez; Arjan Verweij; Rob Wolf
Chaired by: Dr. Siemko, Andrzej
General information
After finishing the powering of sector 4-5, there will be a series of reviews. A general hardware commissioning review will be held in two weeks. Before that, an internal review of MPP will be organized next week on Thursday or Friday morning. There will also be a review of electrical measurements together with the ElQA team. R. Schmidt added that the already existing safety procedures for powering stand alone magnets over 1kA may be re-discussed.Inner triplet powering
H. Thiesen presented the electrical circuit topology. There are three power converters (PC) in a single circuit. A single quadrant 7kA PC(1) feeding the external current leads and a single quadrant 5 kA PC(2) feeding only Q2. A third, four quadrant 0.6kA PC(3), is connected to the leads of Q1. The first conclusion from this configuration is that the voltage in the PC1 may become negative when decreasing the current in Q1 (PC3) and thus become unstable. The three power converters share a global current loop to avoid this. The current is not recorded in the magnet but in the power supplies. If needed for analysis, the current in each magnet can be computed on-line. Action: SACEC.To protect the circuit in case of quench of any magnet, additional paths for the current have been provided by adding free wheeling diodes and a thyristor. The current decay after a fast power abort in all three power converters ranges from 100 to 430 s making it the longest decay in the LHC (QF/QD are about 400s). The diodes and thyristor are water cooled but in the event of a water cooling fault, the heat during the discharge could damage the free wheeling diodes The present solution consist on firing the quench heaters when a water fault is detected. This is not acceptable from the point of view of the magnets. As a short term solution, It is proposed to fire the quench heaters only if one of the PC is above 3kA. A delay will also be added before the quench heaters are fired. In the long term (six months), a thermal couple will be installed in the leads and the heaters will only be fired if the temperature is too high. It is estimated that, after the implementation, the quench heaters will be fired due to a water fault once in the life time of the inner triplet. Both solutions do not imply any modification of the PIC. MPP endorsed the proposal and required that the short term solution is implemented before the first powering of the inner triplet. Action AB/PO
S. Feher presented in detail the magnets in the inner triplet and the relevant issues for the powering tests (see slides).
The cryogenic control of the power leads requires controlling the flow rate in the 600 A leads. This will be addressed in a future meeting. Action CPP.
The quench performance of these magnets implicates few or no training quenches up to nominal current. The polarity of the current leads in the DFBX has been recently found incorrect. Fermilab has worked together with the ElQA team to solve the problem and relabel the current leads but this numbering does not correspond to the one used by the QPS system. Action: Mr. Polarity and QPS team.
Quench signals as measured in KEK and Fermilab were shown. The parameters of the quench heaters tested in KEK are not knwon. Action: S. Feher
The reasons for the fragility of the quench heater wires in the LHC magnets and where we can found problems will be the subject of a future presentation. Action: G. Kirby.
The powering procedure for the inner triplet will be circulated for approval as soon as possible as powering could take place in week 12. Action: editors. The powering procedure for the correctors will be prepared separately. Action editors plus W. Venturini Delsolaro and R. Wolf.
Simultaneous powering of a group of circuits (PGC)
C. Robles presented the nominal tests and powering cycle for the arc PGC tests and the particular case of the sector 4-5. From the full series of tests and to match the tests with the time remaining a set of tests were retained by the panel (see slide).For these tests the main circuits are defined as RB, RQD, RQF and the 6 kA individually powered quadrupoles (Q7-Q10 in both sides of the arc).
- Check of the global protection system. This will allow to test the logic of the PIC once the global protection is connected. All circuits in the arc (main and correctors) will be powered at their injection currents. Correctors are powered to their nominal values as their injection value is defined as zero. A fast power abort is provoked in one of the main circuits. The fast power abort should propagate to the other main circuits. Non commissioned corrector circuits are closed to check if the switches open correctly. This test will be done three times using a different main circuit.
- Electromagnetic compatibility test. All circuits are brought up (2kA for main circuits and maximum commissioned current for the correctors). After reaching the flat top, all the 600 corrector circuits are tripped (FPA) one after the other. The main circuits should not react. If successful, the main circuits are ramped down slowly.
- DFB and current leads performance. All circuits are brought up together (9 kA for RB and RQF/D, the equivalent escalated value for the 6kA quadrupoles and the maximum reached current in the correctors). After a plateau of ten minutes all circuits are brought down to zero current and re-ramped up again. The second plateau becomes the heat run that will end by a FPA in the RB circuit.
The remaining issues are postponed due to lack of time.
Last updated on 13 February by N. Catalan Lasheras
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