How to calculate moisture content in oil?

[Quicksilver1]

Anyone know how to calculate the amount of water in transformer oil based on testing results? Is there a calculation based on paperweight and gallons of oil? I've done a search and did not find what I was looking for. If there is something already out there, please direct me to it. Thanks.

 

[electricpete]

As I recall most of the water resides in the paper.
There are some inferences that can be made under assumption of equilibrium conditions and knowing the temperature.
I recall the Piper chart was a useful one.
Lots of charts here:

https://www.ee.washington.edu/research/seal/pubfiles/00744585.pdf

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(2B)+(2B)' ?

 

[electricpete]

I guess I should back up and say that you can calculate the quantity of water directly in the oil simply by treating ppm as a fraction. Estimating the quantity of water in the paper is the trickier part which requires the chart above.

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(2B)+(2B)' ?

 

[oldfieldguy]

Electricpete correctly points out that the moisture of oil in a transformer is an ever-changing number. Your latest test results tell you how much water is in the oil at that time.

Simply put, water in a transformer will migrate from one medium, oil, to another medium, cellulosic insulation and back depending on temperature and time.

Also simplistic, warm oil absorbs moisture better than cold oil.

Given enough time between temperature changes water will migrate back and forth between the two. However, if the oil cools faster than the cellulosic insulation can absorb, water may drop out of solution.

old field guy