H1 was in OBSERVING for about 40min this afternoon (until a smaller aftershock knocked us out yet again!). But when we were at NLN, had a couple of SDF Diffs (see attached for channels) for:
- ISI ITMx TRamp (chose to NOT MONITOR)
- SEI PROC (ISI_DIFF was in ON state. This basically means we have the new CPS Diff in the ON state (I phoned Jim and he walked me through this new system). He suggested we NOT MONITOR this channel, but I think in a rush to get back to OBSERVING, I ACCEPTED instead.)
Note On CPS Diff
This had been OFF, but for some reason it was ON for my most recent lock. I called Jim and so he could help me out---this is a new system from Jenne, Chiari, & Jim. I mentioned that with all the EQs, I had tried to transition the SEI_CONF to EARTHQUAKE & Large EARTHQUAKE a few times. Thinking possibly this is how CPS Diff was turned ON, but that's a guess on my part. Anyway, it was ON according to SDF & Jim explained it to me.
For better performance in the wind/earthquake bands, we run with CPS DIFF---> ON (see alog). Jim suggested to leave CPS Diff ON. It is good to leave ON as long as the microseism is below 0.4um/s (we are currently at about 0.15um/s).
If microseism gets above 0.4um/s (and it looks like we are getting glitches in DARM), then we should transition CPS Diff to OFF. Jim suggested one can do this by going to the SEI_DIFF Guardian Node and taking it from FULL_DIFF_CPS state to the DOWN state. Alternatively, one can also turn the CPS Diff bit to the OFF state on the Output Limiters medm. The attached screenshot shows ISI_CONFIG, the SEI_DIFF guardian node, and the LSC Output Limiters medm (the ways to turn CPS Diff OFF are circled in green & have arrow pointing to them.).
Thank you, Corey and Jim.
Jim is right, and I should have used the guardian to turn off CPS DIFF. Because I had just turned off the DIFF control switch rather than using the guardian, the guardian was able to turn CPS DIFF back on by itself.
Jim and I implemented at the end of November a decorator in the SEI_DIFF guardian to turn off all SEI DIFF control if any ISI platforms are not in their nominal states. So, when the platforms tripped due to the recent earthquakes, the SEI DIFF guardian correctly went to its DOWN state. Since the request was still set to FULL_CPS_DIFF, once all the platforms were back online the guardian turned the CPS DIFF back on. If I had done the more correct thing, and used the guardian to turn off CPS DIFF when we had high microseism (which would have required a guardian code change to the nominal state), then the guardian would have just stayed in the DOWN state when the ISIs were back online.
Tagging OpsInfo.