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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: 15413     Entry time: Fri Jun 19 07:40:49 2020     In reply to: 15410     Reply to this: 15415
Author: Jon 
Type: Update 
Category: VAC 
Subject: Questions/comments on vacuum 

I think we should discuss interlock possibilities at a 40m meeting. I'm reluctant to make the system more complicated, but perhaps we can find ways to reduce the reliance on the turbo pump readbacks. I agree they've proven to be the least reliable.

While we may be able to improve the tolerance to certain kinds of hardware malfunctions (and if so, we should), I don't see interlocks triggering on abnormal behavior of critical equipment as the root problem. As I see it, our bigger problem is with all the malfunctioning, mostly end-of-lifetime pieces of vacuum equipment still in use. If we can address the hardware problems, as I'm trying to do with replacements [ELOG 15412], I think that in itself will make the interlocking much less of an issue.

Quote:

So why not just have a special mode for the interlock code during pumpdown and venting, and during normal operation we expect the main volume pressure to be <100uTorr so the interlock trips if this condition is violated? These can just be EPICS buttons on the Vac control MEDM screen. Both of these procedures are not "business as usual", and even if we script them in the future, it's likely to have some operator supervising, so I don't think it's unreasonable to have to switch between these modes. I just think the pressure gauges have demonstrated themselves to be much more reliable than these TP serial readbacks (as you say, they worked once upon a time, but that is already evidence of its flakiness?). The Pirani gauges are not ultra-reliable, they have failed in the past, but at least less frequently than this serial comm glitching. In fact, if these readbacks are so flaky, it's not impossible that they don't signal a TP shutdown? I just think the real power of having these multi-channel diagnostics is lost without some AND logic - a turbopump failure is likely to result in an increase in pump current and temperature increase and pump speed decrease, so it's not the individual channel values that should be determining if an interlock is tripped.

Ok, this can be added pretty easily. Its value will just be toggled between 1 and 0 every time the interlock server raises/clears the existing string channel. Adding the channel will require restarting the whole vac IOC, so I'll do it at a time when Jordan is on hand in case something fails to come back up.

Quote:

It would be better to have a flag channel, might be useful for the summary pages too. I will make it if it is too much trouble.

ELOG V3.1.3-