KAGRA Logbook

CRY (Cryostat EY)

shinji.miyoki - 20:05 Friday 28 February 2025 (32855)

Two EY Payload Cryocoolers started

Around 17:30, two EY Payload Cryocoolers started.

Because the power suppliers for EY IM heater seemed to be in error mode, I restarted them. Ushiba-kun checked the healthy status of the power supplier for the IM heater. According to Ikeda-san, the error reset seemed to be possible via LAN. So, we asked him to prepare the reset function for all power suppliers for all Type-A suspensions.

Comments to this report:

shinji.miyoki - 20:11 Friday 28 February 2025 (32856)

We found that one of the cryocooler's cooling performances was so strange.

Fig.1 shows the REF4 4K/50K HEAD cooling performance is not smooth,c compared with REF2 4K/50K HEAD.

I, Ushiba-kun, and Kimura-san discussed it, and we decided to monitor it until the next morning.

Images attached to this comment

32856_1740741045_Screenshot from 2025-02-28 20-10-05.png

satoru.ikeda - 10:23 Saturday 01 March 2025 (32858)

> Because the power suppliers for EY IM heater seemed to be in error mode, I restarted them.

This error is caused by a voltage drop in the input AC power supply.
Since a minimum of 85 Vac is available, this means that the voltage has dropped below this level.
I recommend that you first check the quality of the power supply and the environment.

Non-image files attached to this comment

japanese.txt

tomotada.akutsu - 11:17 Saturday 01 March 2025 (32859)

That should be a severe case...

takahiro.yamamoto - 18:28 Saturday 01 March 2025 (32860)

Which AC source is used for these power suppliers? A common outlet in DGS rack or dedicated one?

If a common outlet is used:
A common outlet was used for an AC source of IO chassis, an function generator for LVDT, etc. in the past and it was stably enough for driving them. If these power suppliers are particularly weak compared to IO chassis or function generators, then we should prepare a recovery method in addition to improvement of environment (only what we can do is installing an UPS? But from the view point of noise in DGS rack, UPS had better to be installed to a rack outside of VIS room). And also I wonder another devices connected to this common outlet (if remains) detected a voltage drop or not.

If dedicated one is used:
An environment should be already much better than the common outlet. In this case what we can do for improving is less than the case of using the common outlet.

shinji.miyoki - 10:27 Sunday 02 March 2025 (32861)

The cooling performance for the ARM side duct shield seemed to be recovered. Then the temps at Duct SHIELD ARM1/4 started decreasing before the critical temp of ~ 157K. The timing of the temp reverse at ARM4 seemed to be delayed by one day from ARM1.

No serious vacuum pressure level enhancement at the GV_eya position, etc has not been detected up to now.

Images attached to this comment

32861_1740878809_Screenshot from 2025-03-02 10-26-40.png

shinji.miyoki - 8:57 Monday 03 March 2025 (32868)

The temp at EYC1F and maybe 2F increased by 0.3C because of the two more cryocooler operations.

I adjusted the Sunrise and Delonghi heaters' power around 9:00 to reduce the temp at EYC area.