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Entry  Thu Jun 11 11:48:43 2020, gautam, Update, VAC, Vac failure vacFailure.png
    Reply  Thu Jun 11 16:14:03 2020, gautam, Update, VAC, Vac failure - probable cause is serial comm glitch TP2_tempGlitch.pngPSL_shutterClosed.pngTP2tempGlitches.pdf
       Reply  Thu Jun 11 17:35:34 2020, gautam, Update, VAC, Pumpspool UPS needs battery replacement 
          Reply  Fri Jun 12 01:23:32 2020, Koji, Update, VAC, Pumpspool UPS needs battery replacement 
             Reply  Fri Jun 12 17:32:40 2020, Koji, Update, VAC, Pumpspool UPS needs battery replacement Screen_Shot_2020-06-12_at_17.22.23.png
                Reply  Fri Jun 12 19:02:52 2020, gautam, Update, VAC, Pumpspool UPS needs battery replacement 
                   Reply  Fri Jun 12 19:23:56 2020, Koji, Update, VAC, Pumpspool UPS needs battery replacement 
                      Reply  Fri Jun 12 19:33:31 2020, gautam, Update, VAC, Pumpspool UPS needs battery replacement 
                         Reply  Tue Jun 16 13:35:03 2020, Jon, Update, VAC, Temporary vac fix / IFO usable again Pumpdown.png
                            Reply  Wed Jun 17 16:27:51 2020, gautam, Update, VAC, Questions/comments on vacuum 
                               Reply  Thu Jun 18 11:00:24 2020, Jon, Update, VAC, Questions/comments on vacuum 
                                  Reply  Thu Jun 18 12:00:36 2020, gautam, Update, VAC, Questions/comments on vacuum 
                                     Reply  Thu Jun 18 14:13:03 2020, Jon, Update, VAC, Questions/comments on vacuum 
                                        Reply  Thu Jun 18 15:46:34 2020, gautam, Update, VAC, Questions/comments on vacuum 
                                           Reply  Fri Jun 19 07:40:49 2020, Jon, Update, VAC, Questions/comments on vacuum 
                                              Reply  Fri Jun 19 09:57:35 2020, gautam, Update, VAC, Questions/comments on vacuum 
Message ID: 15407     Entry time: Thu Jun 18 12:00:36 2020     In reply to: 15406     Reply to this: 15408
Author: gautam 
Type: Update 
Category: VAC 
Subject: Questions/comments on vacuum 

I agree there were MEDM fields, but I can't find any record of these channels being recorded till 2018 December, so I don't agree that they were being digitally monitored. You can also look back in the elog (e.g. here and here) and see that the display fields are just blank. I would then assume that no interlocks were dependent on these channels, because otherwise the vacuum interlocks would be perpetually tripped.

Looking at images of the old vac screens, the TP2/3 rotation speed and status string were digitally monitored. However I don't know if there were software interlocks predicated on those.

Sorry but I'm having trouble imagining a scenario how the pressure gauges wouldn't register this before the IFO volume is compromised. Is there some back of the envelope calculations I can do to understand this? Since both the pressure gauges and the TP diagnostic channels are being monitored via EPICS, the refresh rate is similar, so I don't see how we can have a pump temperature / speed / current threshold tripped but NOT have this be registered on all the pressure gauges, seems like a bit of a contrived scenario to me. Our thresholds currently seem to be arbitrary numbers anyway, or are they based on some expected backstreaming rate? Isn't this scenario degenerate with a leak elsewhere in the vacuum envelope that would be caught by the differential pressure interlocks?

The temperature and current interlocks are implemented precisely because the pumps can shut themselves off. The concern is not about damaging the pumps (their internal logic protects against that); it's that a pump could automatically shut down and back-vent the IFO to atmosphere. Another interlock (e.g., the pressure differentials) might catch it, but it would depend on the back-vent rate and the scenario has never been tested. The temperature and current interlocks are set to trip just before the pump reaches its internal shut-down threshold.

For the email alert, can you expose a soft channel that is a flag - if this flag is not 1, then the service will send out an email.

That would be awesome if you're willing to volunteer. I agree this would be great to have.
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