betsy.weaver@LIGO.ORG - posted 19:51, Tuesday 06 December 2016 - last comment - 04:13, Wednesday 07 December 2016(32282)
CP4 1 day trend - currently in alarm
CP4 LTY250 pump level went into high alarm 20 mins ago. Cell phones have received alarms. Waiting to talk to Chandra or someone VE...
The current alarm is not the normal "glitchiness" that has been ongoing for the last few days - 20 mins ago this signal jumped from ~95 to 100 and is riding up there. See attached.
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Got a hold of Kyle. He is looking into it from home and will call back to advise if any action is required.
This is mostly a nuisance that we don't yet understand. Chandra reduced the "smoothing factor" (I love it!) from ~99.9 to 0.00 a day or so ago at John's suggestion but this doesn't seemed to have changed the behavior. We are mostly concerned with low pump levels as opposed to high pump levels these days. We have opened the exhaust check-valve bypasses on all 80K pumps on site. This eliminates any over "pressure" situations that could have been a threat in the past during rapid pump fillings or too high LN2 pump levels. For tonight, OPERATORS please post 4 hour trends (thanks Betsy) twice per shift. The Vacuum members will monitor from home.
It's on the bounce again...
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I instructed Travis to put CP4 in manual mode with the LLCV at 35% open overnight. The software limit of 25% is great when the pump level is too high but nothing prevents it from going too open if the PID gets a pump level signal of too low. At least in Manual mode the crazy swings will stop. We can deal with it in the morning.
A couple hours in now on MANUAL at 35% open. Not alarming high anymore.
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Seems to still be stable.
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Level has been slowly dropping for the last 3 hours. If this continues, I may have to give VE and early wake up call.
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