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Message ID: 101     Entry time: Thu Jun 9 21:41:25 2005
Author: Willy Andersson 
Operational Mode: Quench Recovery 
Subject: Trying to achieve stable cooling. 
From about 08:00 to 15:00

See Doug's previous entry for quench recovery details.
First the system had been set to // cold return mode because the solenoid 
temps seemed low enough. Temps started to rise instead of cooling so system 
was eventually set back to // warm return mode. With the system in // warm 
return mode the solenoid was still warming instead of cooling. Solenoid 
temps were rising to almost 50K and T1 shield heater was about 90%. T1 
inlet temp was below 75K and falling even with shield heat set so high. 
CV155 kept closed and // warm return flows were full flow. T1 brake valve 
seemed way too open at about 0.8 (compared to previous runs).

15:00 to 19:00

Tried opening CV155, didn't seem to help much. Temps still trending 
upwards. Decided to reduce flow to solenoid to see if the cold box would 
cool down. Started reducing the // warm return outlet valves. TI121 began 
to drop slowly. On graph plotting solenoid temps they started to trend 
downwards. Weird. A reduced flow seemed to produce more cooling ? Don't 
understand this but will continue. Flow temps returning from solenoid were 
about the same temp as TI121, about 35 K. Switching to // cold return mode 
to try to reduce TI121. Keeping CV155 as open as possible, just keeping 
CV204 from closing completely. After switching to // cold return TI121 
starts to slowly fall, T1 inlet temp rises over time so start to drop 
shield heater setting. Solenoid temps now trending downwards. Cracked open 
CV142 to get some flow going through powerleads. Raised compressor 
discharge press to about 11.2 barA. Shield heater down over time to about 
10%. Reduced CV155 down to the point where temps almost stop falling then 
open cv155 just enogh to keep temps falling.

19:30 Solenoid temps down to about 28K. Letting system continue cooling 
overnight.

Guessing the cause of the turbine overspeed quench was caused by 
contamination entering the spinning turbine, causing rapid speed changes or 
possibly the continued saga of the water damaged Jaquet turbine speed 
tachometer giving random false trips.
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