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Message ID: 26     Entry time: Thursday, January 24, 2013, 17:05
Author: Keith C Ng 
Category: Primary Beamlines 
Type: Repair 
Subject: 1A triplet repair (ground fault) 

Continued with work on finding ground fault on 1A triplet;

 

Uncovered Q15 & 16 to 1AS1 area. See photo below for setup.

20130124_tripletrepair_IMG_0040.JPG

  

Disconnected last years thermocouple cable (coil circuit #9) at connector, no effect on ground fault.

- Removed connector cable rad levels: 10 uSv @ 0.5m 100 uSv on contact. No removable contamination.

- Cable stored in hot block storage.

- Will re-connect in future date and left in 1A service chase.

 

Q15 ground fault appears to be in the cables running into the triplet service chase. Moving beam spill monitor cable (BMS #57) appeared to have most effect on resistance in ground fault.

- Chase and cables shown in photo.

20130124_tripletrepair_IMG_0047.JPG

 

- Wiggled beam monitor cable, resistance varied from 4800 ohm to infinity.

 

T. Moskven disconnected BMS #57 at control rack.

- No change to ground fault resistance, at 4800 ohm.

- T Moskven reconnected BSM control cables after days work was completed.

 

Compared Q16 power supply to ground for reference.

- Disconnected asymmetric steering power leads (1ASM 11A & B) to Q16 and disconnected Q16 power supply.

- Resistance measured at 0.470 M ohm from coil power lead to ground.

- Reconnected magnet power supplies after.

 

Discovered that the aymmetric steering leads (pyrotenax cable) on north side of triplet magnets feeding Q14 and Q16 are disconnected at Q16 power supply.

- D. Preddy recommends leads are unbolted at magnets. Leads appear above the four bus bars in photo.

20130122_tripletrepair_IMG_0011.JPG

 

Q14 resistance was at 250 ohm, Q15 resistance varied between 4800 ohm and infinity.

 

 

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