corey.gray@LIGO.ORG - posted 10:52, Sunday 02 October 2016 - last comment - 10:50, Friday 07 October 2016(30150)
PSL Recovery From Flow Sensor Trip (and Being down/cold for 10+hrs)
(Corey, Jason on phone)
Last night, Nutsinee came in early for her OWL shift & just before midnight the PSL tripped. We opted to leave it tripped for the night to wait for Jason to walk us through recovery procedure. Atleast for now, we always want to run through this procedure with one of our PSL people (Jason or Peter K). Here are my rough notes:
- Control Room PSL card (in key box) just passed its 7-year expiration date on Fri
- Remote login (with Jason)
-
Went through a few steps in procedure and during a 5-min wait, I went out to Fill the low Crystal Chiller.
- Both Chillers were on (but not chilling). The Crystal Chiller (on top) had a "Flow sensor 1" error (but Jason says this is a generic error).
- The cap blew off and was on the floor
- Topped off with 375mL Laboratory Water
- Continued with procedure with Jason
- Once laser back, worked on restoring PSL systems via medm.
- Had to RESET the Noise Eater (toggle switch to OFF [for ~5sec], then ON). This switch is at the "NPRO box" which is the Innolight box on the right most elec cabinet outside of the PSL Room; has the sticker: "AdvLIGO observatory No3" on it.)
- Then brought everything back (actually the PMC, FSS & IMC came back on their own. Had minor actions to bring back the ISS).
- Last task is to wait 30min to hit the LRA button (can't remember what Jason said this stood for) & then ENABLE the Oscillator & Frontend WatchDogs.
- Closed out Remote Login interface.
- Time on phone with Jason: ~60min
Now on to "Aligning" on Observatory Mode!
PSL Status NOTE:
- Have a Warning Red light under the Laser's HPO (not sure what this means).
- ISS Autolock is RED (not sure what this means either since the Autolock is ON & GREEN on the ISS screen).
The Xtal chiller has tripped 3 times in the last week:
then 4 days later:
now 3 days later:
The last two events imply an overpressure condition. The problem seems more significant than replacing lost fluid from a slow leak.
Was the cap which "blew off" in today's event the "bleeding cap" (section 4.2.2), the "filter sleeve cap" (section 6.2) or the "filler pipe cap" (section 6.3 of T1100374-v1, "200 W Laser Crystal Chiller Manual")?
BTW, LRA = Long Range Actuator; see section 7.2 of T0900641-v5, "Under Manual 200 W Laser".
From my quick look through the alog I think the PSL has tripped more than this (for LHO to concur). From what I can see it has gone off 11 times in the last week (thats as far as I looked back).
I'm not sure if all the same problems, but alogs reporting the PSL laser off are LHO alogs:
10/2/2016
LHO alog 30160
LHO alog 30154
10/1/2016
LHO alog 30146
LHO alog 30143
9/30/2016
LHO alog 30118
LHO alog 30086 (due to power glitch)
9/29/2016
LHO alog 30076
LHO alog 30063 (this alog reports two different instances of the laser going off)
9/27/2016
LHO alog 30016
9/25/2016
LHO alog 29964
The filler pipe cap popping out is a known thing (happens all the time at LLO) when the chiller turns OFF. At LLO at least this has not shown to be due to any problem (just a consequence for whatever reason when the chiller is turned off). Its why we try to not turn these chillers OFF if can help it as they "burp" water over the floor and pop these fill caps even when trying to restart
I have as one of the main agenda items of this Wednesdays PSL meeting to discuss this problem and see if we can work out whats going on. Some statistics on how many times happened in say the last month or two, what the PSL trip was attributed to, and how many times happened before and after the chiller swap (to see if accelerating or at the same rate), would help this. Im not sure if FRS fault reports have been made for each laser trip to make this search easy for us remote to the site to do and work out how much lost observatory time we have had due to this issue.
Yes, Dennis, as Matt says it's the Filler Pipe Cap that pops off. We have had (3) trips since Friday evening (so Matt is probably right about there being more trips over the whole week). OH, and I should correct ourselves here because we just had a 4th Weekend PSL trip (this was just after I had H1 at NLN for 15min. This time the cap was blown off and there was a puddle on the floor.
Able to get back in 30min this time (vs 60min this morning).
OK, back to locking.
Another Note:
Something I wanted to add about the chiller was that when filling it, I noticed quite a bit of turbulence in the fill pipe. And you could see a air bubble vortex/tornado in there. Something we probably don't want if air bubbles are postulated as a trigger for flow sensor trips.
We see these bubbles as well in the chiller fill pipe at LLO with no chiller trips due to it (hopefully haven't jinxed myself). Perhaps post a movie of it so can see if looks the same as here
Jason & crew will be investigaing tomorrow. We should ask them to record a video of it.
Movie of the water turbulence of LLO's crystal chiller fill tube posted at LLO alog 28397
I took a video, but I can't post it; my phone only takes video in .mp4 format, which is apparently not a valid file type for upload to the alog. Huh.
I attached a still from the video to give you some idea of what we've been seeing here for the last few weeks. It's appearing to fluctuate though; the video was taken on Monday, 10/3/2016, but this morning our fill port looks very similar to what's seen in Matt's video of the LLO crystal chiller fill port.