Got a call at about 10:00 this morning, the whole system had tripped off. 
No power bumps or other disturbances. When I arrived the only fault 
indications were "ColdBox Trip" light on the compressor panel and on the 
QRL panel the red "ColdBox" LED was ON. On the SULZER panel the 
yellow "Cryostat Quench" light was ON. On the First Trip logger #1 and #15 
LED's were ON. But no indication about what the actual fault was. Cooling 
water OK, compressed air OK, compressor ventilation OK. Outside ambient 
temperature was cooler than we had last week. BIG1 was off but when I 
turned it back on the vacuum looked good but was slowly rising as the 
solenoid warmed. I put the jumper on the vacuum controller. Prepared system 
for re-start.

Started compressor. Started flow thru coldbox. Raised discharge pressure.
Started turbine flow. Didn't get any freezing but it seemed that T1 speed 
wandered slowly +/-0.1k rev/sec when it got up to about 3.6k revs/sec, but 
this only lasted for a second or two. Not sure if I was just seeing things.
Got turbines up to speed and started // warm return flow. Solenoid had been 
running at 500 Amps and when it quenched and sat warming it had warmed to 
about 40 K. Switched it to //cold return too soon and solenoid started to 
warm slightly. Back to // warm return mode. Had to throttle flow thru 
solenoid with warm return valves to get effective cooling. If had return 
valves wide open TI121 would warm up too much. Discovered that if I 
throttle the flow out of the solenoid slightly then TI121 would fall and 
solenoid would start to cool. Less flow gave more cooling. Don't quite 
understand that one. Switched to // cold return mode when solenoid temps 
falling below 20K.

About 15:00 stable // cold return cooling. Going home for a while.

19:30 solenoid temps bottomed out at about 11K. Switch to series mode. 
Something strange about the first trip detect. I reset it once and when I 
checked it an hour or two later it showed a trip on #1 and #15 LED's even 
though nothing had happened. Something must be causing false indications.

20:15 series cooling, solenoid temps at about 6K, LHe level rising slowly 
at about 10%. Removed jumper on vacuum controller.