At 13:47 UTC, Corey put in an alog noting that H1 was unlocked and the PSL was down. I checked the control room screenshots page and saw that DIAG_MAIN was reporting the PMC high voltage was off, and Richard reported that there were two site power glitches early this morning, so I was immediately reminded of a very similar situation in early August where the high voltage supply for PMC locking was tripped off during a power glitch. I got in contact with Corey and Richard (who was on-site) and we coordinated turning the 375V power supply in the CER mezzanine back on. Richard also checked other HV supplies and reported they were on. Once the PMC HV was back on, I proceeded with recovering the PSL from home and ran into no issues. Corey is now relocking H1.
Since the PSL had just turned on, I needed to adjust the ISS RefSignal from -2.00V to -2.06V to keep the diffracted power between 2.0% and 2.5%. This will need to be adjusted again as the PSL thermalizes to keep the diffracted power where we want it; I'll check on this when I'm on-site later this morning.
Attached is a trend of the site power glitch at 10:42 UTC this morning and the PMC HV going down as a result.
Just FYI, here at LLO the PMC HV power supply was the most sensitive to a power glitch (it is what would trip off first, even if the PSL stayed up)
This after a couple attempts we have swapped into the UPS talked about in LLO alog 66808. To date we have had no issues since this particular UPS was installed. We even simulated power outages/power glitches and the PMC HV supply stayed on.
Created FRS 29181 to track PMC HV trips and noted LLO's implementation of an online UPS.