Transcript MPP_Orbit_07052008-part_2

MPP
Result of the investigation in the orbit
correctors faults.
 RCBV27.L6B2 – High value of
magnet resistance during PNO.a1
 RCBCV10.L6B1 – EE811 voltage
tap missing
MPP Meeting 07/05/2008
G. D’Angelo – R. Mompo
RCBCV10.L6B1 – EE811 voltage tap missing
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Chronology of events:
On 11/03/2008, RCBCV10.L6B1 circuit was successfully qualified
by ELQA team.
On 14/04/2008, AB/PO can not power this circuit, they have a
fault on 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.
MPP Meeting 07/05/2008
G.D’Angelo – R. Mompo
RCBCV10.L6B1 – EE811 voltage tap missing
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On 05/05/2008:
Intervention to perform a time domain reflectometry to localize
precisely the defect. It is repairable if it is at the level of the cover
flange.
Surprise! The voltage tap EE811 is back!
Impossible to make a reflectometry as there is no defect
anymore, so I did a few ohmic measurements to check all the
voltage taps.
MPP Meeting 07/05/2008
G.D’Angelo – R. Mompo
RCBCV10.L6B1 – EE811 voltage tap missing
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Measurements on the external « sick » orbit dipole:
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For comparison, measurements on the internal dipole:
*: Measurement performed with a portable multimeter.
MPP Meeting 07/05/2008
G.D’Angelo – R. Mompo
RCBCV10.L6B1 – EE811 voltage tap missing
 Conclusion:
AB/PO have no more interlocks, they can now power the magnet
to qualify the circuit (checked with V. Montabonnet) with the
circuit as is.
Proposal:
We could try to reproduce the defect, by feeding a current of 2
Amps through the voltage taps.
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If the voltage tap remains connected, we close the NC.
If we manage to open the vtap, we perform a time domain reflectometry.
MPP Meeting 07/05/2008
G.D’Angelo – R. Mompo