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fabian.arellano - 21:52 Tuesday 20 April 2021 (16520) Print this report
Thermistor installation

With Hirata-san.

See pictures in album PR3 Remedying Work.

We installed the thermistor. It is held by an assembly attached to a security structure pillar above IRM. See this picture.

  • Each terminal of the thermistor has two cables and all of them are connected to pins in a D-sub 9 connector.
  • Cables connected to one of the terminals go to pins 1 and 2.
  • The cables of the other terminals go to pins 6 and 7.
  • The resistance of the thermistor is 110.8 Ω measured before installation.
  • After installation we measured 112.3 Ω from the outside of the chamber at the feedthrough.
  • See this notebook page.
Comments to this report:
fabian.arellano - 17:47 Wednesday 21 April 2021 (16533) Print this report

With Hirata-san.

Pictures at SR3 remedying work after O3.

Hirata-san re-assembled the thermistor compond with a few changes:

  • He added kapton sheet 12.5 µm thick between the thermistor and the aluminium holder.
  • He covered the legs of the thermistor with PEEK tube.
  • Then he measured the resistance at the in-vacuum male connector between pins 1 and 6: 111.0 Ω which is similar to previously measured values.
  • He re-installed the assembly in the security structure of the suspension.
satoru.ikeda - 20:13 Thursday 27 May 2021 (16864) Print this report

We checked the operation of the thermistors (PT100) in the chambers of PRM, PR2, and PR3.
We connected a temperature control device (KT4R) via a cable from the feedthrough and compared the internal temperature and the temperature with another thermocouple.
The thermocouple was temporarily installed near the thermistor.

optic PT100(°C) Thermocouple(°C) memo
PR3 20.8 23.8 (-3.0)
PRM 21.3 23.2 (-1.9)
PR2 20.9 22.6 (-1.7)

After some time had passed, we checked the temperatures and found that they varied quite a bit.
The temperature of the thermocouple was almost the same as the nearby thermometer.

When I measured again after losing the Dsub extension cable with PR3, the temperature varied considerably.
This was a bit strange since the resistance of a resistance thermometer should not depend on the resistance of the cable.
A little more investigation is needed.

  PT100(°C)  Thermocouple(°C) memo
PR3 22.4 23.8 (-1.4)

Apart from the above, we found a poor contact on the cable of the vacuum chamber side of PR3, which was remedied by Hirata-san.
He used the cable that was to be used for SR, so he did not have a spare.


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satoru.ikeda - 13:12 Friday 28 May 2021 (16877) Print this report

Ikeda, Fabian-san, Hirata-san

We used PR2 to study the difference in temperature between PT100 and thermocouple.
In conclusion, the problem was solved by changing the method of connecting 4 wires to 3 wires.
NG: Connect one side of the four wires (A1, A2, B1, B2) to one side.
  1: A1 2: A2 3: B1+B2
OK: Use only three of the four wires.
  1:A1 2:A2 3:B1 (B2 is empty)

The measured temperatures are as follows.
The difference between the two is so slight that it is considered to be within the error range. 

optic PT100 (°C)  Thermocouple (°C) memo
PR3 23.2 23.4 (-0.2)
BS 22.7 22.8 (-0.1)

However, when the cable in the vacuum chamber of BS was shaken, the temperature values changed significantly.
(It went back and forth from -20.x to about 24.x.)
The same phenomenon was observed in PR3, and it was improved by replacing the cable.
(The change was 0.1°C).
Therefore, I think BS needs to be improved.

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