1. Fault Recovery Time for C100 Modules Spring ‘16
Review of the Digital LLRF Algorithm and Software for the C100 Cryomodules
Fault Recovery Time for C100 Modules
Spring ‘16
Bob Legg
13 June 2016

2. C100 FSD Trip Rates Spring 2016 Before 3/9, there were
29.8 hrs lost in 48 events
over 5 minutes
After 3/26, there were
4.7 hrs lost in 6 events
over 5 minutes

3. Typical Recovery Time Plot

4. Details The recovery times presented are based on the Archiver.
Lengths of time are determined by the difference between a cavity switching to SEL and switching back to GDR modes.
The analysis tool is dumb. It does not correlate fault types (yet) so many of the trips do not have to do with the LLRF; e.g. Vacuum trips in SL often required hours to clear, but were not a LLRF feature.
The analysis tool is dumb. It does not correlate faults between cryomodules, so common faults appear in all data sets. Data from CHL, vacuum valves and burning magnet faults were hand removed.
The recovery times shown are averages, but the standard deviations for them as large as the average because of a few long recovery events. Again, these events do not necessarily have anything to do with the LLRF; e.g. He level goes unsteady as rf is switched off/on during fault and requires 45 minutes to settle.

5. Maximum Time to Recover C100, 25 Jan to 25 April

6. St.Dev=
3.51
St.Dev=
4.64
St.Dev=
3.88
St.Dev=
4.19
St.Dev=
4.34
St.Dev=
3.54
St.Dev=
3.63
St.Dev=
3.26
St.Dev=
3.12
St.Dev=
1.96

7. C100 Recovery Time vs. Time Ver. 71 Ver. 73 NL Update Ver. 74 Ver. 75
Ver. 73 SL

8. Summary Recovery times for the C100 cryomodules are improving.
Recovery times statistics continue to be driven by a few very long recovery events.
Beamline Vacuum valve closures
Helium liquid level and pressure instability
Poor heat management
Recovery times for C100s still are longer than for the C20 or C50 modules.
Please recommend a real Fault Logger be written.