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zamanengineer001
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Join Date: Sep 2011
Posts: 26

Silica Gel in Power Transformer

09/04/2012 7:54 AM

Is there any criteria for the replacement period of silica gel, definitely depend upon the moisture in environment. I have observed 1st change after 10 days (color change) then after 14 days its color again has changed; opinion required.

Moreover criteria for OLTC breather and main tank should be same or different.
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PWSlack
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#1

Re: Silica Gel in Power Transformer

09/04/2012 9:12 AM

The criteria will certainly be stated in the User Manual for the equipment, and will also be made available during a telephone call to the transformer manufacturer's Technical Helpline.

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zamanengineer001
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#2
In reply to #1

Re: Silica Gel in Power Transformer

09/05/2012 6:00 AM

Thanks for the feedback,

OEM manual recomend weekly check but not define any normal period for the color change, actualy I want an estimated time period during normal operation from the people which has experience of it like you :)

please also share any possible reason for abrupt change beside high humidity in environment......

Thanks
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PeterT
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Location: Liverpool, NY
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#3

Re: Silica Gel in Power Transformer

09/05/2012 8:00 AM

The takeup of moisture by the silica gel varies depending on a number of factors, including how humid the ambient atmosphere is (e.g., tropical moisture vs. arid region), time of year, temperature, how much actual airflow there is through the breather, etc. There is no set "time" for changing. Color change is you main indicator. Usually the color changes from the outer vent end of the container toward the tank connection in a gradual range.

The common color of gel I have seen is blue, and changes to pink-orange as it absorbs moisture. When the gel is solidly orange, it is fairly saturated.

It is possible to recondition silica gel by baking out the moisture at low temperature. See the following link for example: http://www.apsnyc.com/uploads/Methods%20for%20Reconditioning%20Silica%20Gel.pdf

You may want to invest in some replacement silica gel, and swap out when needed. You put new gel in the unit, and bake what you take out to use the next time. That way you always have some on hand to put in when needed.

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zamanengineer001
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Join Date: Sep 2011
Posts: 26
#4
In reply to #3

Re: Silica Gel in Power Transformer

09/06/2012 1:20 AM

Peter Thanks for the feedback

If we have two transformer ay the same site, one breather gel changes its color after in 6 to 8 months and other in weeks as i siad previously. what does it indicate.....?
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PeterT
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#5
In reply to #4

Re: Silica Gel in Power Transformer

09/06/2012 11:49 AM

The second unit must be "breathing" faster / more deeply, so the volume of air flowing through it is more and thus more moisture needs to be absorbed. Are they identical transformers? Is it cycling in load or temperature more than the other? You have to compare their operating conditions. Every transformer will be different, so you can't predict one by the other.

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