Issue of Silica Gel Turning Black

I don't know, but the following might lead you to additional information that could help the diagnosis.

1) Can you break open a crystal and see whether it's a surface effect or total thickness?

Surface effect would imply a particulate in the air exchange process

2) What happens when you try to regenerate the crystals? Do they change back, or stay black?

3) What happens to some of the same crystals left in the open in the same room?

4) Do you have a new service technician who replaces the crystals in the cannister. Maybe he/she has some contaminant on them.

5) Is this a "new" problem? (Like has it been satisfactory for a long time and then has changed.)

6) Does the transformer have the correct oil/coolant installed?

7) Is it possible to get a spectroscopic examination to determine what the contaminant is? For a transformer ofthat size, probably worthwhile.

Good luck.

Additional questions to those Just An Engineer posted:

8) Is the oil in the transformer at the proper level? Does the level gauge read correctly?

9) Has the transformer been running through any high temperature swings, which may cause the oil level to raise above maximum acceptable and enter the vent tube to the breather?

10) Were the proper silica gel crystals installed, or are these really not silica gel? Have they done their job in the past, by absorbing moisture and turning pink/orange? Have they been regenerated in the past and reused?

11) It looks like the change is only on part of the crystals. Is it located closest to the vent line from the transformer (suggesting the source of the issue is there) rather than closer to the external vent?

Send a sample to a chemical lab and have it analyzed.

Suggest that you investigate the ambient conditions and the internal condition of the transformer. You may have some internal flashover that generated heat, carbon, and other organic compounds that are contaminating the silica gel. While you're at it, draw some oil samples and have them tested for integrity and dissolved gases, then you'll have some clues what is being breathed out as an indication of what is going on internally. It would also be wise to do some 7x24 monitoring of the air quality around the breather to see what the transformer (and you) breathes in.

Dear All,

Sorry for delay as site was not opening since last 3 days.

Answers to the questions asked:

1) Can you break open a crystal and see whether it's a surface effect or total thickness? Surface effect would imply a particulate in the air exchange process

Ans: It is totally black. It turns to small pieces while minor hitting.

2) What happens when you try to regenerate the crystals? Do they change back, or stay black?

Ans: It stays black.

3) What happens to some of the same crystals left in the open in the same room?

Ans: It still stays black.

4) Do you have a new service technician who replaces the crystals in the cannister. Maybe he/she has some contaminant on them.

Ans: No.

5) Is this a "new" problem? (Like has it been satisfactory for a long time and then has changed.)

Ans: Problem occurred recently only.

6) Does the transformer have the correct oil/coolant installed?

Ans: Yes.

7) Is it possible to get a spectroscopic examination to determine what the contaminant is? For a transformer ofthat size, probably worthwhile.

Ans: I have to verify the possibility of examination.

8) Is the oil in the transformer at the proper level? Does the level gauge read correctly?

Ans: Oil level is Ok. Checked.

9) Has the transformer been running through any high temperature swings, which may cause the oil level to raise above maximum acceptable and enter the vent tube to the breather?

Ans: Maximum temp is 52 deg celcius only.

10) Were the proper silica gel crystals installed, or are these really not silica gel? Have they done their job in the past, by absorbing moisture and turning pink/orange? Have they been regenerated in the past and reused?

Ans: These silica gel is being used in 32 trafo, everywhere else these are fine.

11) It looks like the change is only on part of the crystals. Is it located closest to the vent line from the transformer (suggesting the source of the issue is there) rather than closer to the external vent?

Ans: It is close to both vents, I am not able to locate the starting point, whether it is at top or bottom of breather.

Reply of RAMconsult is a matter of serious concern and may be a possibility. I will check it accordingly and revert back the findings.

Regards,

Gaurav

I'm not sure why #5 is marked off topic since it contains the answers to the concerns raised in the prior posts.

Regarding the path that the vapors took; normally the discoloration takes place evenly from top to bottom, after all the breather is drying out the air that is being sucked into the transformer as it cools down, and there shouldn't be any moisture being expelled from the interior of the transformer. The paths through the silica gel indicate that something was forcibly ejected from the bottom to the top, taking the path of least resistance instead of meandering uniformly through the dessicant.

It will be interesting to see the oil and dissolved gas analyses.

Agreed on the OT.

Maybe the OP did it inadvertently, or the "auto-OT generator" has a bad moment.

Sorry to mark it off topic. It was done by mistake.

Yesterday I again opened breather to check whether there started any discoloration, from bottom or top. Found nothing.

I will check it after 1 week and update the same.

It does not become black till date. Just slightly light blue, which is normal in monsoon season. Shall update if some abnormality observed.