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MP3 meeting
Participants
Adriaan Rijllart
Andrea Musso
Antonio Perin
Bernhard Auchmann
Christian Giloux
Christine Darve
Francesco Bertinelli
Gianluigi Arduini
Howard Pfeffer
Hugues Thiesen
Jim Strait
Markus Zerlauth
Mike Koratzinos
Nuria Catalan Lasheras
Robert Henry Flora
Sandor Feher
Sandrine Le Naour
Scheuerlein Christian
Vittorio Remondino
Walter Venturini Delsolaro
Zinur Charifoulline
MP3 meeting 28 October 2009
The voltage drifts and then suddenly recovers, initially it had been supposed due to valve opening or closing on the current lead
in some cases the two were indeed correlated, but not always
Bob asked whether the voltage changes were real
Yves said yes, as they give I_ERR
Walter suggested it may be a malfunctioning of the power converter, as it was the case for RCBH3.L2
Nuria said it might be easier to change the PC
It was pointed out that this is not for the moment an operational issue and that if we change the pc it will be necessary to recommission the circuit.
In general the situation is good, but there was a discussion concerning the missing channels and the noisy channels
So far the QPS team has accepted pyramids if at least 95% of the channels were present
However this had never been discussed in MP3 and was based on informal communications
Nuria said that all the channels should be present
Walter asked how noisy a channel must be to be considered a missing channel
Zinur said that noisy channels still allow to give upper estimates of the resistance in the nano Ohm range
Howard Pfeffer said that for 2000 A it shoud be enough to get one board
Mike Koratzinos said that one pyramid was not sufficient to achieve the accuracy requested
Bob remarked that we take two sets of data, one for each board
Howard reminded that both boards will have to be operational before connecting to the interlock
Mike said that there are splices not covered by the new QPS
Sandrine asked what should be the criterion for the MP3 signature
It was recalled that the procedure states 50 nOhm for "intra" splices and 10 nOhm for "inter"splices
Nuria suggested that MP3 should not sign in case of missing channels
After some discussion it was agreed that MP3 recommends to acquire at least one measurement for each splice before handing over the circuits to operations
In the case of RQX.R5 for example, the temperature diverged after one hour
RQTL9.L7B1 needs valve replacement
In general, Antonio Perin commented that last year the whole LHC was operated with on off regulation on the current leads
PID regulation currently adopted is more sensitive to valve malfunctioning due to friction
If necessary we can roll back to on off.
Nuria remarked that the current leads will have to be thoroughly checked during PGC
After discussion it was decided to maintain the heater induced quench.
It was however noted that in a previous meeting it had been agreed that some of the cryogenics experts members of MP3 would provide the list of magnets with the highest quench propagation to the neighbours
It was not clear at the time of the meeting whether this had been done
Noise on RCO (Yves Thurel)
Yves showed plots of voltage "noise" in RCO circuits, not fully understoodThe voltage drifts and then suddenly recovers, initially it had been supposed due to valve opening or closing on the current lead
in some cases the two were indeed correlated, but not always
Bob asked whether the voltage changes were real
Yves said yes, as they give I_ERR
Walter suggested it may be a malfunctioning of the power converter, as it was the case for RCBH3.L2
Nuria said it might be easier to change the PC
It was pointed out that this is not for the moment an operational issue and that if we change the pc it will be necessary to recommission the circuit.
Status of splice mapping (Zinur Charifoulline)
Zinur presented the status of splice mapping in the various sectorsIn general the situation is good, but there was a discussion concerning the missing channels and the noisy channels
So far the QPS team has accepted pyramids if at least 95% of the channels were present
However this had never been discussed in MP3 and was based on informal communications
Nuria said that all the channels should be present
Walter asked how noisy a channel must be to be considered a missing channel
Zinur said that noisy channels still allow to give upper estimates of the resistance in the nano Ohm range
Howard Pfeffer said that for 2000 A it shoud be enough to get one board
Mike Koratzinos said that one pyramid was not sufficient to achieve the accuracy requested
Bob remarked that we take two sets of data, one for each board
Howard reminded that both boards will have to be operational before connecting to the interlock
Mike said that there are splices not covered by the new QPS
Sandrine asked what should be the criterion for the MP3 signature
It was recalled that the procedure states 50 nOhm for "intra" splices and 10 nOhm for "inter"splices
Nuria suggested that MP3 should not sign in case of missing channels
After some discussion it was agreed that MP3 recommends to acquire at least one measurement for each splice before handing over the circuits to operations
Current leads regulation issues (Sandrine Le Naour)
Sandrine showed several plots of current lead regulation, which have been submitted to her by the ccc crew.In the case of RQX.R5 for example, the temperature diverged after one hour
RQTL9.L7B1 needs valve replacement
In general, Antonio Perin commented that last year the whole LHC was operated with on off regulation on the current leads
PID regulation currently adopted is more sensitive to valve malfunctioning due to friction
If necessary we can roll back to on off.
Nuria remarked that the current leads will have to be thoroughly checked during PGC
AOB
Gianluigi Arduini asked what modifications should be made to the PGC procedure, given the reduced IPNO of the main circuitsAfter discussion it was decided to maintain the heater induced quench.
It was however noted that in a previous meeting it had been agreed that some of the cryogenics experts members of MP3 would provide the list of magnets with the highest quench propagation to the neighbours
It was not clear at the time of the meeting whether this had been done
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The agenda of this meeting is empty