40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  ATF eLog  Not logged in ELOG logo
Message ID: 2737     Entry time: Sat Mar 26 12:49:18 2022
Author: Stephen 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: Warmup started, issue with steady state heating 

25 March 2022 (Friday) at 21:00, went to QIL to start warmup.

 - Cryocooler was turned off at 21:21

 - Heater output was disabled - it seemed there was an issue, and therefore I opted for passive warmup only.

 

Heater Issue Troubleshooting

Symptom: Heater Output was enabled but reporting only .35 W and "Err" indicator.

Symptom: When output was disabled, a fan noise was terminated. When output was reenabled, the same fan kicked back on. The fan was driving much harder than I had ever heard it before.

Symptom: The output indicated .35 W but the test mass temperature was 66 K. Past heater power for steady state at 120 K was on the order of 1 W.

Per CTC 100 manual:

   - pg 9 (100W heater outputs) indicates: "If the temperature of either PCB exceeds 60°C, the CTC100 automatically shuts off the corresponding output" which was not the case.

   --> Apparently not an overtemperature situation.

   - pg 9 (Hardware faults) indicates a list of error conditions which are accompanied by pop up windows.

   --> This error had no pop up window, not quite sure what to make of that except that the controller doesn't think our issue is something it can identify.

   - pg 29 (The system fan) notes that "The main system processor reads the desired fan speed from each I/O card and sets the fan to the fastest requested speed".

   --> Suggests that the louder fan noise may have indicated higher temperature condition, even if not an over tempearature condition.

   - pg 41 (Numeric) describes that in the typical numerical view of the data channels, the message "Err" that I saw on the heater channel indicates "an internal error has occurred".

   --> No explanation of what an "internal error" is, but in this case I suspect it could reflect that the heater output is not coupled the input Workpiece temperature.

Best Guess: the symptoms and the lack of any apparent controller-identified fault suggests that the heater may have debonded. I didn't look at temperature history, so I'm not sure if there was a point where the heater was bonded to the test mass during this run.

Next Steps: We should open up and investigate.

ELOG V3.1.3-