Shutdown raith SNF 2008-03-19 14:06:47: vacuum controller board failure

jwc at snf.stanford.edu jwc at snf.stanford.edu
Wed Mar 19 16:28:17 PDT 2008


We had a very unusual event in the lab today. The event occurred at 13:14 hours and I was in the SNF Ebeam lab at the time.
LEO server indicated a vacuum connection failure to sensors in the vacuum control card. Raith was called for further phone and troubleshooting support at 13:57 hours.
Upon checking sub-systems interlocked to the vacuum controler board it was determined that water flow had been interupted sourced from the NESLAB chiller.  Appears to be a manual trip of the power switch on the neslab chiller unit. It is unlikely that this was a overcurrent breaker trip as it was found not to need to be reset just repowered to 'on'.  
I could not reproduce this failure this afternoon.
System is now up -- pumped down and I just brought the gun back up.  Available for the next user in the Coral queue at this time.
System load lock, mechanical and turbo pumps, switch and relay interlocks to the E/O and Vacuum controler cards have been tested.
Chiller flow is well below specification at 0.2 lpm (spec is 2 lpm)  I will request that raith engage this problem and find a longer term solution.
James Conway




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