KAGRA Logbook

DGS (General)

satoru.ikeda - 10:20 Thursday 27 August 2026 (37420)

Momentary Power Outage and Computer Reboots at Both End

At approximately 08:22:44 JST on August 27, 2026, a momentary power outage occurred at both end, causing four computers k1ex1, k1ex0, k1ey1, and k1ey0 to reboot. All four computers were back online by 08:25:19 JST.
The ADC and DAC cards were recognized normally, indicating that the I/O chassis likely continued operating without interruption.
Only k1ey0 showed an unusually high IRIGB_TIME value of 27, compared with the normal value of approximately 11. To restore it to normal, all real-time models on k1ey0 were restarted.

Regarding systems other than the real-time models, the Picomotor controller cannot be reached by ping from k1ex1. This issue may be unrelated to the power outage, but it appears to require an on-site inspection and will be checked during the next visit.

Images attached to this report

37420_1787794859_Screenshot from 2026-08-27 09-33-44.png

Non-image files attached to this report

japanese.txt

Comments to this report:

satoru.ikeda - 12:23 Friday 28 August 2026 (37426)

Nakagaki-san, ikeda

The ETMX Picomotor controller had remained powered off.

The Picomotor controller had not been turned back on following the electrical equipment inspection with a blackout in March.

This issue was unrelated to the cause of the real-time PC reboot.

Corrective action:
We powered on the controller and confirmed that it could be accessed via MEDM.

Non-image files attached to this comment

japanese.txt

satoru.ikeda - 12:55 Friday 28 August 2026 (37427)

Included for informational purposes

A follow-up investigation found that, according to information from Hokuriku Electric Power Company, a power outage occurred in Kamioka at around the same time (08:22 on August 27, 2026), and power was automatically restored.
Although it isn't included in the town's name, so I can't say for sure, it may have been related.

Images attached to this comment

Non-image files attached to this comment

japanese.txt

satoru.ikeda - 12:00 Tuesday 01 September 2026 (37439)

Based on the information in K-Log #37433, an additional investigation was conducted to determine whether any AC alarms had occurred.
The IM Heater and CRY Stepper were checked, and AC input undervoltage protection (AC-FAIL) errors were found. After the inspection, all alarms were cleared.

For details about AC-FAIL, please refer to the following website: link

Based on these results, it is presumed that a momentary voltage drop occurred throughout, including the center area, rather than only at both ends, although the extent of the impact varied depending on each device’s threshold.

IM HEATER
EX: AC-FAIL error
EY: AC-FAIL error
IX: No error
IY: AC-FAIL error

CRY Stepper
EX: AC-FAIL error
EY: AC-FAIL error
IX: No error
IY: AC-FAIL error

For reference:

The equipment that can be controlled via the web interface uses the following two regulated DC power supplies.
The PWR401MH is equipped with AC input undervoltage protection (AC-FAIL).
The PMX70-1A does not have this function; therefore, it is assumed to have recovered automatically after the momentary power interruption.

A list of the equipment used is available on the following page:
https://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA/Subgroups/DGS/Projects/IMHeater

Images attached to this comment