corey.gray@LIGO.ORG - posted 13:39, Tuesday 17 August 2010 - last comment - 14:19, Tuesday 17 August 2010(132)
Unit#2 Collocated Undamped Plant (Transfer Function) Via Matlab
This is the first set of Matlab transfer functions run on Unit#2. This was run via Fabrice's measurement files made for Unit#1. This is a collocated measurement (i.e. H1 to H1, H2 to H2...V1 to V1, etc. versus X to X, ...RX to RX, etc.). This measurement was run WITHOUT DAMPING. Something Amiss At a first glance, something looks wrong with the GS13's. H3 & V3 look noticeably different from H1H2 & V1V2. But as Hugh noticed, when you look at the same measurement for Unit#1 (seen in this document), the H3 & V3 plants on Unit#2 look like all the plants on Unit#1. So not really sure what's the issue here. The Capacitive Position Sensors look fine at a first glance.Will continue making more plant (transfer function) measurements and keep an eye on the GS13's. Have attached pdfs of the plants to this elog.(sorry, they're in portrait...I don't know how to print things in landscape on matlab). ****Below are the locations of the measurement files (they've been svn-added & committed)*** All files are at [seiteststand svn]: /opt/svncommon/seisvn/seismic/HAM-ISI/X1/ MEASUREMENT FILE LOCATION: [seiteststand svn]/Scripts/DataCollection/unit_2/ FILE NAMES: TFcollect_100816_L2L_0p05to0p5Hz.m TFcollect_100816_L2L_0p05to5Hz.m TFcollect_100816_L2L_5to200p5Hz.m TFcollect_100816_L2L_200to800Hz.m DATA FILE LOCATION: [seiteststand svn]/Data/unit_2/TransferFunctionData/ FILE NAMES: TFcollect_100816_L2L_0p05to0p5Hz_test1mat.mat TFcollect_100816_L2L_0p05to5Hz_test1.mat TFcollect_100816_L2L_5to200p5Hz_test1.mat TFcollect_100816_L2L_200to800Hz_test1.mat PLOTTING/DATA-CONCACENATING FILE LOCATION: [seiteststand svn]/Scripts/DataAnalysis/unit_2/ FILE NAME: TFanalyze_100816_L2L.m .pdf & .fig FILE LOCATION: [seiteststand svn]/Data/unit_2/Figures
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It should be mentioned that the 200-800Hz part of this measurement was run last night (Monday 8/16). The 5-200Hz, 0.5-5Hz, and 0.05-0.5Hz measurements were run today (Tuesday) during the day when there was noisy assembly work going on at Unit#3 (but the Watchdog never tripped for these measurements).
There is definitely something wrong on H1,H2,V1,V2 seismometers. Don't they share the same interface chassis? Can we check if everything is ok with the chassis (power supply, current limit...) This explains why the damping loop was unstable; on the attached document: - First page, I follow up on Corey's filter measurement from yesterday. I compare it to the design. It matches. No problem here. - On the second page, I plot the open loop using the measurements Corey has just posted. It cross over at 1.4Hz with negative phase margin. Everything should work once we find out what is wrong with these 4 GS13s.
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