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Entry  Sun Aug 5 13:45:00 2018, gautam, Update, SUS, ETMX tripped ETMX_tripped.pngETMX_tripped_zoom.png
    Reply  Thu Aug 9 12:40:14 2018, gautam, Update, SUS, ETMX trip follow-up ETMXglitch.png
       Reply  Mon Aug 13 09:56:23 2018, Steve, Update, SUS, ETMX trip follow-up ETMXglitch.pngETMXgltch.png
          Reply  Thu Aug 23 08:24:38 2018, Steve, Update, SUS, ETMX trip follow-up ETMX-UL_glitch.pngPEM_4d.png
             Reply  Fri Aug 24 14:58:30 2018, Steve, Update, SUS, ETMX trips again glitches.png
Message ID: 14156     Entry time: Mon Aug 13 09:56:23 2018     In reply to: 14150     Reply to this: 14178
Author: Steve 
Type: Update 
Category: SUS 
Subject: ETMX trip follow-up 

Here is an other big one


A brief follow-up on this since we discussed this at the meeting yesterday: the attached DV screenshot shows the full 2k data for a period of 2 seconds starting just before the watchdog tripped. It is clear that the timescale of the glitch in the UL channel is much faster (~50 ms) compared to the (presumably mechanical) timescale seen in the other channels of ~250 ms, with the step also being much smaller (a few counts as opposed to the few thousand counts seen in the UL channel, and I guess 1 OSEM count ~ 1 um). All this supports the hypothesis that the problem is electrical and not mechanical (i.e. I think we can rule out the Acromag sending a glitchy signal to the coil and kicking the optic). The watchdog itself gets tripped because the tripping condition is the RMS of the shadow sensor outputs, which presumably exceeds the set threshold when UL glitches by a few thousand counts.


Attachment 1: ETMXglitch.png  56 kB  | Hide | Hide all
Attachment 2: ETMXgltch.png  42 kB  Uploaded Mon Aug 13 11:45:44 2018  | Hide | Hide all
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