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Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits

                                                                                         Introduction




                                                   Superconducting Electrical Circuits




1
                                                                              Introduction


                                                                           Superconducting Electrical Circuits
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                            Hardware Commissioning started seriously in April 2007.

                                                                            It was interrupted many times for various reasons and lasted until
                                                                            th D d      in total      th
                                                                            the D-day, i t t l 18 months.
                                                   g




                                                                            The organization of the work was constantly improved and
                                                                            reached a very satisfactory level .
                                     S




                                                                            (except when I maximized the confusion)

                                                                            The work was done according to ever improving procedures,
                                                                            prepared and polished by MPP.




                                                                                                                                                 2
                                                                              Disclaimer


                                                                           Superconducting Electrical Circuits
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                            The work was done by numerous people from many groups.
                                                   g




                                                                            The results were obtained by the ELQA, QPS, OP, MPP, PO, Cryo,
                                                                            and the HC teams (somebody forgotten? Apologies!)
                                     S




                                                                            I’m just reporting other peoples observations, as I recall them. I
                                                                            added the mistakes.

                                                                            This talk is about surprises and mysteries.




                                                                                                                                                 3
                                     S             g
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits


                                                                           The greatest surprise!




                                                   It almost worked!




4
                                                                                Other surprises


                                                                           1.
                                                                           1             Non Conformities
                                                                                   Known Non-Conformities
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                          (fixed)
                                                                           2.      Discovered Non-Conformities
                                                   g




                                                                                          (now fixed ?)
                                                                           3.      Re-Discoveries
                                     S




                                                                           4.      Unexpected Discoveries




                                                                                                                 5
                                                                           Other surprises

                                                                           1.   Known Non-Conformities (fixed)
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           2.   Discovered Non-Conformities (now fixed ?)
                                                                           3.   Re-Discoveries
                                                                           4.
                                                                                Not treated here
                                                                                Unexpected Discoveries
                                     S             g




                                                                                                                            6
                                                                           Other surprises

                                                                           1.
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           2.    Discovered Non-Conformities (now fixed ?)


                                                                                     D3, Q4,
                                                                                •The D3 Q4 Q5 puzzle
                                                   g




                                                                                •The RQT12.R3 etc puzzle
                                                                                •The MQM5.L8 bus problem
                                                                                      Q           p
                                     S




                                                                                •The Russian #mas present (QF45)




                                                                                                                             7
                                                                           First Indication of Linkage between D2 & Q4        [1]




                                                                                           D2 Spontaneously
                                                                                            Quenches as it
                                                                                          approaches Nominal
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                    50 mS later Q5 Trips
                                                                                        due to QPS             500 mS later
                                                                                         Imbalance             Q4 Quenches
                                                                                                                    why???
                                                                                                                but why???
                                     S             g




                                                                                                                                    8
                                                                             The D2 Q4 puzzle


                                                                           The D2 was quenching when the Q4-B1 was at high value

                                                                           The Quench was likely in the part, where the power busses are in the
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           DFBM “side-by-side”
                                     S             g




                                                                                                                                                  9
                                                                               The D2 Q4 puzzle


                                                                           Once the cable where shaken into place, no quench occurred any more
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                     S             g




                                                                           The fault is still in the LHC and may show up again, here and elsewhere.
                                                                                                                                                      10
                                      S             g
 Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits

                                                                            The RQT12R3.B1 (etc) puzzle




11
                                                                               The RQT12R3.B1 (etc) puzzle
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                     S             g




                                                                           Ures (red) continues to rise while the current (green) is constant. A clear sign of a
                                                                           quench As this was the case for all correctors served by the outer layer of the
                                                                           quench.
                                                                           SCL cable, it was concluded that the link does not work properly. Problem was
                                                                           found in a cold bridge. Fixed (?)
                                                                                                                                                                   12
                                                                            Other surprises

                                                                            1.           Re-Discoveries
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           •The Q6.R4 (and similar) puzzle
                                                                                         p                         puzzle
                                                                           •The inner triplet current distribution p
                                                   g




                                                                           •The undulator puzzle
                                                                           •The inner triplet 600A lead problem
                                                                                                   re-start
                                                                           •The RB (and similar) re start problem after a quench
                                     S




                                                                                                                                   13
                                                                                                                   The Q6.R4 puzzle

                                                                               Negative Current ? Q6.R4 assymmetric quench
                                                                                                               2.00E-02

                                                                                                                          Corresponds to 2000 A
                                                                                                                                p                                                ?
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                                               1.50E-02
                                                                           Voltag drop ov current lead (~ to




                                                                                                               1.00E-02
                                                                                                                          Centre tap @ 1600 A
                                                                                                               5.00E-03
                                                   g




                                                                                                           0.00E+00                                                                           DFLCS.P1.Loc.LD1:U_RES
                                                                                        urrent)




                                                                                                                    0.00E+00 2.00E+00 4.00E+00 6.00E+00 8.00E+00 1.00E+01 1.20E+01 1.40E+01
                                                                                                                                                                                              DFLCS.P1.Loc.LD2:U_RES
                                                                                                          -5.00E-03
                                                                                                                                                                                              DFLCS.P1.Loc.LD3:U_RES
                                                                                        ver
                                                                                       cu
                                     S




                                                                                                          -1.00E-02


                                                                                                          -1.50E-02
                                                                                ge




                                                                                                          -2.00E-02
                                                                                                                          Corresponds to 3600 A
                                                                                                          -2.50E-02


                                                                                                          -3.00E-02                              Time [s]



                                                                                                                                                                                                                       14
                                                                                                                   The Q6.R4 puzzle

                                                                               Negative Current ? Q6.R4 assymmetric quench
                                                                                                               2.00E-02

                                                                                                                          Corresponds to 2000 A
                                                                                                                                p                                                ?
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                                               1.50E-02
                                                                           Voltag drop ov current lead (~ to




                                                                                                               1.00E-02
                                                                                                                          Centre tap @ 1600 A
                                                                                                               5.00E-03
                                                   g




                                                                                                           0.00E+00                                                                            DFLCS.P1.Loc.LD1:U_RES
                                                                                        urrent)




                                                                                                                    0.00E+00 2.00E+00 4.00E+00 6.00E+00 8.00E+00 1.00E+01 1.20E+01 1.40E+01
                                                                                                                                                                                               DFLCS.P1.Loc.LD2:U_RES
                                                                                                          -5.00E-03
                                                                                                                                                                                               DFLCS.P1.Loc.LD3:U_RES
                                                                                        ver
                                                                                       cu
                                     S




                                                                                                          -1.00E-02


                                                                                                          -1.50E-02                                                                           Lead resistance to
                                                                                ge




                                                                                                          -2.00E-02
                                                                                                                          Corresponds to 3600 A                                               be   incl ded
                                                                                                                                                                                                   included
                                                                                                          -2.50E-02


                                                                                                          -3.00E-02                              Time [s]
                                                                                                                                                                                              Similar but
                                                                                                                                                                                              Si il b t more
                                                                                                                                                                                              complicated for the
                                                                                                                                                                                              inner triplets            15
                                                                                   The Undulator Puzzle(s)                                                                                                 [2]


                                                                           Circuit diagram
                                                                                                                                                      And the other one is missing a
                                                                                                                                                      resistor.
                                                                                                                                                      Different transfer functions.
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                                                                                      Slow ramp rates!

                                                                            Ri= 0.15 Ω; L(i) function of current, 1.5 H at 450 A
                                                   g




                                                                                                                                   6


                                                                                                                                                       Gap field (T)
                                                                                                                                   5
                                                                                                                                                       Computed inductance (H)
                                     S




                                                                                                 RPMBB.UA47.RU.R4                  4             EE


                                                                                                                                   3



                                                                                                                                   2
                                                                                                            Rextr= 0.8 Ω

                                                                                                                                   1



                                                                                                                                   0
                                                                                                                                       0   50   100      150       200      250        300   350   400   450     500
                                                                                                                                                                         Current (A)
                                                                                                                                                                                                                   16
                                                                              Problems to re-start after a quench

                                                                           On Jan. 30th 08 the quench protection trips, while ramping up. It turned
                                                                           out that a “reference magnet” had quenched in the run before. (used as
                                                                           representative for the whole sector to calculate the L di/dt)
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           Quench Protection Reference Magnets

                                                                                   Dipoles                          Quadrupoles
                                                   g




                                                                           "1-2"   MB.C21R1      MB.C21L2           MQ.A21R1         MQ.A20L2
                                                                           "2-3"   MB.C21R2      MB.C18L3           MQ.A21R2         MQ.A17L3
                                                                           "3-4"   MB.C21R3      MB.C18L4           MQ.A20R3         MQ.A18L4
                                                                           "4 5"
                                                                           "4-5"   MB.C21R4
                                                                                   MB C21R4      MB.C21L5
                                                                                                 MB C21L5           MQ A20R4
                                                                                                                    MQ.A20R4         MQ.A20L5
                                                                                                                                     MQ A20L5
                                     S




                                                                           "5-6"   MB.C21R5      MB.C21L6           MQ.A20R5         MQ.A20L6
                                                                           "6-7"   MB.C21R6      MB.C21L7           MQ.A20R6         MQ.A20L7
                                                                              8
                                                                           "7-8"      C
                                                                                   MB.C21R7      MB.C21L8
                                                                                                    C   8            Q
                                                                                                                    MQ.A21R7          Q 0 8
                                                                                                                                     MQ.A20L8
                                                                           "8-1"   MB.C21R8      MB.C21L1           MQ.A20R8         MQ.A20L1

                                                                           If one of the above magnets has quenched, a special procedure for repowering has to
                                                                               applied                          recover     course
                                                                           be applied. This costs extra time to recover, of course.


                                                                                                                                                                 17
                                                                            Other surprises
                                                                                          Unexpected Discoveries

                                                                           •The symmetric quench problem (see Reiners talk)
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           •The transient spike problem
                                                                           •The coupling Q4-D2.L8 (and similar)
                                                                           •The quench back of correctors incl. coupling
                                                                            The
                                                   g




                                                                           •The RCO.A78B2 splice
                                                                           •The RQT13.L5B1 splice (or what)
                                                                                RCBCV10 L6B1
                                                                           •The RCBCV10.L6B1 threat
                                     S




                                                                           •The RD2.L2 and RD3.L4 limitations
                                                                           •The RCBY mystery
                                                                           •The extremely fast quench propagation mystery
                                                                           •….minor issues….


                                                                                                                              18
                                                                           The transient spike problem                                     [3]




                                                                           Quench detected in MB B30 (MB 1007) during fast discharge at
                                                                           7000A => dI/dt =-70A/s
                                                                                            quench.
                                                                           There is no real quench There is a voltage difference between the
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           two apertures which grows with dI/dt and exceeds 100mV.
                                                                           Magnetic measurement in SM18 during ramp had also shown a
                                                                           different dynamic behaviour of the aperture with a unusually high
                                                   g




                                                                           sextupole in one aperture. Also no particular asymmetry between
                                                                           upper and lower poles.
                                                                           The behaviour in the machine seems therefore identical to the
                                     S




                                                                           behaviour in SM18, where this magnet was trained to 12KA as
                                                                           usual.




                                                                                                                                                 19
                                                                           The transient spike problem                              [4]




                                                                           Quench detected in MB B30 (MB 1007) during fast discharge at
                                                                           7000A => dI/dt =-70A/s
                                                                                            quench.
                                                                           There is no real quench There is a voltage difference between the
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           two apertures which grows with dI/dt and exceeds 100mV.
                                                                           Magnetic measurement in SM18 during ramp had also shown a
                                                                           different dynamic behaviour of the aperture with a unusually high
                                                   g




                                                                           sextupole in one aperture. Also no particular asymmetry between
                                                                           upper and lower poles.
                                                                           The behaviour in the machine seems therefore identical to the
                                     S




                                                                           behaviour in SM18, where this magnet was trained to 12KA as
                                                                           usual.




                                                                                                                                               20
                                      S             g
 Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits

                                                                            Ua + Ub, Opening EE switch at 3 kA
                                                                               [5]




21
                                                                           Ua + Ub calculated from U1, U2, U3, U4




                                                                                         Reconstructed inter-aperture
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                         voltage difference
                                     S             g




                                                                                                                        22
                                      S             g
 Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                                                            Zinour’s snap-shot tool
                                                                              [6]




23
                                      S             g
 Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits

                                                                            Zinour’s snapshot tool




24
                                                                            Zinour’s snap shot tool
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                     S             g




                                                                           Changing the threshold is potentially dangerous!!!!

                                                                                                                                 25
                                                                            Zinour’s snap shot tool
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                                   g




                                                                           The same tool is also used to measure the
                                                                           Difference in resistance in the two
                                     S




                                                                           apertures of the main magnets to a precision of
                                                                             10nΩ.
                                                                           ~ 10 Ω



                                                                                                                             26
                                                                                                  EM Coupling between standalone magnets

                                                                           Coupling between Q4 and D2 (not powered)
                                                                              4.00E+03                                                                   0.3

                                                                                                                                The common cabling path induces a signal
                                                                                              3.50E+03                          in the neighbors' quench detector, which is
                                                                                                                                                       0.25
                                                                                                                                               Quench.
                                                                                                                                considered as Quench In this case the D2
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                              3.00E+03                          was not powered.
                                                                                                                                This phenomenon has 0.2been observed in
                                                                                              2.50E+03                          several cases. Mainly a problem for
                                                                            Curre in Q4 [A]




                                                                                                                                cryogenics and recovery.
                                                   g




                                                                                                                                                         0.15    I_A : RQ4.L8B2
                                                                                              2.00E+03
                                                                                                                                                                 I_A : RQ4.L8B1
                                                                                                                                                                 Loc:U_RES_B1 : RD2.L8
                                                                                ent




                                                                                              1.50E+03
                                                                                                50 03
                                     S




                                                                                                                                                         01
                                                                                                                                                         0.1


                                                                                              1.00E+03
                                                                                                                                                         0.05

                                                                                              5.00E+02


                                                                                                                                                         0
                                                                                              0.00E+00
                                                                                                          0   1   2   3   4     5    6     7    8    9

                                                                                              -5.00E+02                   Time [s]                       -0.05



                                                                                                                                                                                         27
                                                                           The quench back of correctors leads to coupling                    [7]



                                                                                   RSD2_A45B2
                                                                           Dump of RSD2 A45B2 @ 550 A
                                                                                                        In the beginning the current decay is
                                                                                                        given by the external resistor. After 50 ms
                                                                                                        the quench back due to the internal by-by
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                                        pass resistors sets in.
                                                                                                        The decay is very fast and is easily
                                                                                                        picked up on channels, which are “close
                                                                                                        by”, inducing current
                                                                                                        b ” ind cing c rrent changes or
                                                   g




                                                                                di/dt~ 10 kA/s
                                                                                                        quenches.

                                                                                                                y                 g
                                                                                                        Basically a nuisance during
                                     S




                                                                                                        commissioning but probably also a
                                                                                                        danger for extended dipole/quadr.
                                                                                                        Quenches at high excitation. Run away?

                                                                                                        Also other transients talk to neighbors,
                                                                                                        which can lead to sudden, unforeseen
                                                                                                        current excursions. Danger for beam
                                                                                                        loss?

                                                                                                                                                      28
                                                                                 The RCO.A78B2 splice                                                     [8]
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                     S             g




                                                                                       (red
                                                                           The voltage (red, orange) rises with the current (green) and explodes (quench) after ~4
                                                                           minutes. Bad splice. How to find that one?
                                                                           Out of operation.
                                                                                                                                                                     29
                                                                           RQT13.L5B1, RQTF.A45B2, ?                                             [7]



                                                                           549.9 A                                   Quench
                                                                           550 A     28 S after FT                   Quench
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           550 A     90 S after FT   Trip Reason? (not quench or ground fault)
                                     S             g




                                                                                                                                                       30
                                                                           RQT13.L5B1, RQTF.A45B2, ?

                                                                           549.9 A                                   Quench
                                                                           550 A     28 S after FT                   Quench
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           550 A     90 S after FT   Trip Reason? (not quench or ground fault)
                                     S             g




                                                                                                                                                 31
                                                                                  RQT13.L5B1, RQTF.A45B2, ?

                                                                                 549.9 A                                     Quench
                                                                                  550 A    28 S after FT*)                   Quench
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                  550 A    90 S after FT     Trip Reason? (not quench or ground fault)


                                                                                 525 A                                       Quench
                                                   g




                                                                                 362 A                                       Quench
                                                                                  454A                                       Quench
                                     S




                                                                                 550 A     32 S after FT                     Quench
                                                                                 550 A      2 S after FT                     Quench
                                                                                 550 A     24 S after FT                     Quench
                                                                                 500 A     26 S after FT                    EE Dump

                                                                                           p
                                                                           Is there a bad splice hidden somewhere?
                                                                           Is reducing the nominal current enough???
                                                                           *) Flat Top
                                                                                                                                                         32
                                                                             The RCBCV10.L6B1 (etc) threat




                                                                           On 11/03/2008, RCBCV10.L6B1 circuit was successfully qualified by ELQA team.
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                            On 14/04/2008             t       this i it they have a f lt on th PC
                                                                            O 14/04/2008, AB/PO can not power thi circuit, th h     fault   the PC.
                                                                            On 16/04/2008, EE811 (cold voltage tap) is found open, directly from the feed
                                                                            through pin coming from the cover flange => NC 908215 opened.
                                                   g




                                                                           On 05/05/2008:
                                                                           Intervention to perform a time domain reflectrometry to localize precisely the
                                                                           defect. It is repairable if it is at the level of the cover flange.
                                     S




                                                                           Surprise! The voltage tap EE811 is back!




                                                                                                                                                            33
                                                                            RCBCV10.L6B1 – EE811 voltage tap missing



                                                                           Measurements on the external « sick » orbit dipole:
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                                   g




                                                                                  p                                       p
                                                                           For comparison, measurements on the internal dipole:
                                     S




                                                                                *: Measurement performed with a portable multimeter.   34
                                                                            RCBCV10.L6B1 – EE811 voltage tap missing



                                                                           Measurements on the external « sick » orbit dipole:
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                                   g




                                                                           Avoid the use,
                                                                           it may switch off at any time!
                                                                                  p                                       p
                                                                           For comparison, measurements on the internal dipole:
                                     S




                                                                                *: Measurement performed with a portable multimeter.   35
                                                                               The RD2.L2 and RD3.L4 limitation
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                     S             g




                                                                                      re/de-training.
                                                                           Looks like re/de training
                                                                           What to do?




                                                                                                                  36
                                                                              The RD2.L2 and RD3.L4 limitation
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                     S             g




                                                                                                     150 ms !!!




                                                                           What to do? Are there more? Quadrupoles?

                                                                                                                      37
                                      S             g
 Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                                                            So far, most of what I said is understood, now comes




38
                                      S             g
 Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits
                                                                            So far most of what I said is understood, now come




                                                            The Mysteries




39
                                                                           The RCBY mystery and other strange 120 A magnets
                                                                           Transp. prepared by Mirko




                                                                            Some 120 A magnets quench (?) at a critical di/dt,
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                                    nominal,
                                                                            sometimes very close to nominal during discharge

                                                                              It is ALWAYS when current goes towards 0 A
                                                   g




                                                                              Some magnets, which show this strange behavior also have a
                                                                            different transfer function, and have to be specifically trimmed for
                                                                            control
                                     S




                                                                              High inductances (2.84 - 5.27 H)




                                                                                                                                                   40
                                                                                     The RCBY mystery and other strange 120 A magnets                    [9]



                                                                                                                     TFM @ cold in Q4 and Q5 R8

                                                                           100000
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           10000                      RCBYH4.R8B1

                                                                                                      RCBYV4.R8B2 to compare

                                                                                                      RCBYHS5.R8B1

                                                                                                       C   S
                                                                                                      RCBYHS5.R8B2 to compare
                                                   g




                                                                                  1000
                                                                           Module [Ohm]




                                                                                          100
                                                                           M
                                     S




                                                                                           10




                                                                                           1
                                                                                                1           10                            100     1000
                                                                                                                       Freqency [ ]
                                                                                                                          q   y [Hz]




                                                                                                                                                               41
                                                                                             The RCBY mystery and other strange 120 A magnets

                                                                                                                         TFM @ cold in Q4 and Q5 R8
                                                                           120
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           100
                                                                                                          RCBYH4.R8B1
                                                                                                          RCBYV4.R8B2 to compare
                                                                                                          RCBYHS5.R8B1
                                                                               80                         RCBYHS5.R8B2 to compare
                                                   g


                                                                           Phase [deg]




                                                                               60
                                     S




                                                                               40




                                                                               20




                                                                                         0
                                                                                             1                10                           100        1000
                                                                                                                           Freqency [Hz]



                                                                                                                                                             42
                                                                                             The RCBY mystery and other strange 120 A magnets

                                                                                                                         TFM @ cold in Q4 and Q5 R8
                                                                           120
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           100
                                                                                                          RCBYH4.R8B1
                                                                                                          RCBYV4.R8B2 to compare
                                                                                                          RCBYHS5.R8B1
                                                                               80                         RCBYHS5.R8B2 to compare
                                                   g


                                                                           Phase [deg]




                                                                               60
                                     S




                                                                               40
                                                                                                                                           Why do identical
                                                                               20
                                                                                                                                           magnets have different
                                                                                                                                           transfer functions?
                                                                                         0
                                                                                                                                           What is going on?
                                                                                             1                10                              100             1000
                                                                                                                           Freqency [Hz]



                                                                                                                                                                     43
                                                                           The RCBY mystery and other strange 120 A magnets
                                                                           Transp. prepared by Mirko


                                                                                               RCBYHS4.L5B1
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                                                    I_ref
                                     S             g




                                                                                                                              I_meas




                                                                                                                                       44
                                                                           The RCBY mystery and other strange 120 A magnets
                                                                           Transp. prepared by Mirko
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                                      IDC = 72A
                                                   g




                                                                                      Converter Stops, firing
                                                                                      crowbar, then developing 7V
                                                                                      across Magnet, then dI/dt >
                                                                                      1.3A/s
                                                                                      => Quench
                                     S




                                                                                                                    IDC = -68A   dI/dt = ±1.25A/s




                                                                                                                                                    45
                                                                              The RCBY mystery and other strange 120 A magnets
                                                                              Transp. prepared by Mirko


                                                                           Electrical circuit             Fault                     Critical ramp rate
                                                                           RPLB.RR53.RCBYHS4.L5B1         Cannot handle LHC di/dt   0.6 A/s (LHC: 0.66A/s)
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           RPLB.UA87.RCBYHS5.R8B1 Cannot handle LHC di/dt           0.46 A/s (LHC: 0.66A/s)

                                                                           RPLB.UA87.RCBYH4.R8B1          Cannot handle LHC di/dt   0.6 A/s (LHC: 0.66A/s)
                                                   g




                                                                           RPLB.UJ83.RCBCH7.L8B1          Quench @ discharge        > 2.5 A/s (LHC: 1A/s)
                                     S




                                                                           RPLB.UA23.RCBYH4.L2B2
                                                                           RPLB UA23 RCBYH4 L2B2          Q    h   di h
                                                                                                          Quench @ discharge          1.25 A/ (LHC 0.66A/s)
                                                                                                                                    > 1 25 A/s (LHC: 0 66A/ )

                                                                           RPLB.RR13.RCBCV8.L1B2          Quench @ discharge        1.2 A/s (LHC: 1A/s)

                                                                           RPLB.UJ23.RCBCV7.L2B2          Quench @ discharge        > 2.5A/s (LHC: 1A/s)

                                                                           RPLB.UA43.RCBYV5.L4B2          Cannot reach nominal          Rated 72 A, it
                                                                                                                                            t   higher
                                                                                                                                      cannot go hi h
                                                                                                          current
                                                                                                                                         than 65 A

                                                                                                                                                                46
                                                                             The next mystery: very fast quench propagation


                                                                           Observations:

                                                                           We have em transmission ~ 150 μs/dipole. This includes the spike problems.
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           We h             heat
                                                                           W have 30 … 40 s h t wave t        i i
                                                                                                       transmission.

                                                                           We observed in a few cases times of ~ 100 … 200 ms.
                                     S             g




                                                                                                                                                        47
                                                                             The next mystery: very fast quench propagation


                                                                           Observations:

                                                                           We have em transmission ~ 150 μs/dipole. This includes the spike problems.
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           We h             heat
                                                                           W have 30 … 40 s h t wave t        i i
                                                                                                       transmission

                                                                           We observed in a few cases times of some 100 ms.
                                                   g




                                                                                                                      100 ms scale
                                                                                                                      Induced quench @ 7500 A
                                     S




                                                                                                                                                        48
                                                                             The next mystery: very fast quench propagation


                                                                           Observations:

                                                                           We have em transmission ~ 150 μs/dipole. This includes the spike problems.
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           We h             heat
                                                                           W have 30 … 40 s h t wave t        i i
                                                                                                       transmission

                                                                           We [12] observed in 4 cases times of some 100 ms.
                                                   g




                                                                                                                              Fast Quench Propagation
                                                                                                                                   4 cases found
                                                                                                          600
                                                                                                    ms]
                                                                                Difference in Time [m




                                                                                                          500
                                     S




                                                                                                          400
                                                                                                          300
                                                                                                                                                               to Neighbour Quench Start [mS]
                                                                                                          200                                                  to Neighbour Heater Fire [mS]

                                                                                                          100
                                                                                                            0
                                                                                D




                                                                                                                0   2000     4000     6000      8000   10000
                                                                                                                           Magnet Current [A]
                                                                                                                                                                                                49
                                                                             The next mystery: very fast quench propagation


                                                                           Observations:

                                                                              have em transmission ~ 150 μs/dipole. This includes the spike problems.
                                                                           We The observed current dependence is, at least partially, due to the
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           We have 30 field s h t wave transmission
                                                                              h               heat             i i
                                                                           W current &… 40 dependence t the critical current & temperature.
                                                                                                         of
                                                                              The data are compatible with a constant time delay between
                                                                              observed in current times of some 100 development/ detection.
                                                                           We magnets + a4 cases dependent quench ms.
                                                   g




                                                                                                        Fast Quench Propagation
                                                                              Note that also in the event of the 19. a similar (not the same)
                                                                                                               4 cases found
                                                                              behavior can be found. [13]
                                                                                                          600
                                                                                                    ms]
                                                                                Difference in Time [m




                                                                              Th observation was unexpected and may contain physics.
                                                                                   b
                                                                              The 500   ti              t d d          t i h i
                                     S




                                                                                                          400
                                                                              If the phenomenon is more likely at higher peak temperatures, we
                                                                                    300
                                                                                   y p     p              quench p p g
                                                                              may expect spectacular fast q                         g   tog
                                                                                                                   propagation at high magnet Quench Start [mS]
                                                                                                                                           Neighbour
                                                                                    200
                                                                              currents.                                                 to Neighbour Heater Fire [mS]

                                                                                                          100
                                                                              Interesting times ahead!
                                                                                     0
                                                                                D




                                                                                                                0   2000     4000     6000      8000   10000
                                                                                                                           Magnet Current [A]
                                                                                                                                                                        50
                                                                            Summary


                                                                           •We rediscovered Ohms law.

                                                                           •We rediscovered that superconductivity happens at low
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           temperatures.

                                                                           •We rediscovered Faradays law.
                                                   g




                                                                           •We rediscovered Kirchhoffs law.

                                                                                                                     complications.
                                                                           •We discovered shortcomings & operational complications
                                     S




                                                                           •We discovered that we have not understood everything.
                                                                             There are more things in heaven and earth, Horatio,
                                                                             Than are dreamt of in your philosophy.

                                                                           •The re-commissioning will be very exciting!


                                                                                                                                      51
                                                                                 Summary

                                                                                                 law.
                                                                           •We rediscovered Ohms law

                                                                           •We rediscovered that superconductivity happens at low
                                                                           temperatures.
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           •We rediscovered Faradays law.
                                                   g




                                                                           •We rediscovered Kirchhoffs law.

                                                                           •We discovered shortcomings & operational complications.
                                     S




                                                                           •We discovered that we have not understood everything.

                                                                            The re-commissioning
                                                                           •The re commissioning will be very exciting!

                                                                           •A challenge again! Good luck!



                                                                                                                                      52
                                                                             References


                                                                           [
                                                                           [1] G. Kirby, Commissioning Review of Q4 D2 & Q5
                                                                           [2] W. Venturini Delsolara
                                                                           [3] ] Rob Wolf, MPP Minutes 18.6.08
                                                                           [4] EDMS No: 357674. HCLBBR_000-CR001007, Magnetic Measurement Test Report, S. Sanfilippo, L. Bottura, V. Granata, R.K. Mishra /
Chamonix 2009, K. H. Meß, DG-PRJ-LHU Superconducting Electrical Circuits




                                                                           LHC-MTA
                                                                           LHC MTA
                                                                           [5] Mateusz Bednarek & Jaromir Ludwin (ELQA AT/MEI-FP) MPP Minutes 2.7.08
                                                                           [6] Zinour Charifouline, MPP Minutes 16.7.08
                                                                           [7] K. H. Mess, G.-J. Coelingh, K. Dahlerup-Petersen, EPAC 08, TUPC134
                                                                           [8] S.LeNour, private communication
                                                                           [9] R. H. Flora, private communication
                                                                           [10] G. d’Angelo, private communication
                                                                           [ ]          g     p
                                                   g




                                                                           [11] G. d’Angelo, private communication
                                                                           [12] R. H. Flora, private communication
                                                                           [13] S. LeNaour, Taskforce Report, to be published
                                     S




                                                                                                                                                                                                              53

				
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