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User name Ewing/Fansler
Log entry time 13:59:42 on May 25, 2007
Entry number 203202
keyword=Cryo problems
Last night at approximately 11 PM right Q2 tripped on liquid level. The
shift leader called to report the problem. We troubleshot over the phone
checking temperatures and valve activity. The magnet recovered and we
were able to reset the faults and run again. We were unable to determine
if we had a liquid level meter problem, or a cryogenics problem. This
morning we investigated the problem further, and determined that the 16
valve card on the right Q1 failed open, causing the Q2 trip we
experienced Thursday night. After closer examination, we determined that
the liquid level meter for right Q2 was also not giving us an accurate
indication of liquid level. We replaced the valve card for the 16 valve
on right Q1 and replaced the liquid level meter for right Q2. Both
problems were resolved. Q2 ramped normally, but the Q1 displayed
multiple faults, and would not respond to a reset command. We cycled
power on the Saclay rack and the power supply with no joy. We
disconnected the communications cable from the control panel and
re-installed…no joy. Mark noticed that the Saclay rack was giving us an
indication of a cryogenics fault. The liquid level meter was set to trip
at 60%, and the current liquid level was 68%????? We disconnected the
analog/relay out cable and the contactor cycled normally. This fixed the
problem. We reset the Saclay rack, and power supply. The power supply
ramped normally and the cryogenics appear to be stabilizing. We will
continue to monitor the cryogenics.
A copy of this log entry has been emailed to: fansler@jlab.org, stevensm@jlab.org