1. Context at P8 Last slide presented at LMC early May 2012
In fact we just re-installed Cold Compressor No2 (one repaired in Japan and suspicious spare validated in Lab)
Tests resumed last Thursday, not yet completed.
24VDC down
heater down
=> Delicate operation, 12hrs before getting to the long 36 hrs recovery
09May'12
LMC

2. 21Sept’12 - 1.8K unit for sector 81(&78)
Faulty Heater % of flow generated stopped, getting below minimum tolerated by CCs
Impossible to re-connect at low pressure without it!
Decision to fill the pumping line to a pressure compatible with reconnection at higher pressure without the heater,
But higher pressure means as well higher temperature and long recovery!
09May'12
LMC

3. Milestones
During TS#3, several strange effects on some instrumentation for this sub-system. Team investigating in cavern Friday when complete stop of 1.8K unit at 16h. 24VDC power unit found down, exchanged (medium term situation since 2010 with 2-3 failures/year, type test ready, global upgrade >= LS1)
Restart on tracks with sectors connected when 400V heater failure stopped it again at 22h. As 2nd time in 1 year, decision to go slowly without it (investigation to be foreseen when possible)
12hrs of delicate operation with control algorythm not correctly described, well mastered Saturday noon
≈36hrs of recovery for 2 sectors left without cooling for ≈18hrs…
We will validate the 2nd refrigerator in the coming days, and get organised for diagnostic and repair of the heater (window t.b.d)
09May'12
LMC