Moisture in Transformer Fluid

[JBD]

We have just finished sampling R-Temp fluid filled substation style transformers. The transformers are from various manufacturers and range from 10-15 years old. Eight of the samples all moisture in them.

Does any one know if this is typical of R-Temp fluid from that time period? Any suggestions as to prevent this from happening again?

 

[Sargardani]

First of all... how much moisture did you find? For R-Temp Fluid I believe the max allowed moisture content is 35ppm.

Sarg

 

[JBD]

The lowest one was 65ppm.

 

[wfowfo]

What type of transformers are they? Gas blanketed, conservator, etc.?

 

[JBD]

They are a standard "plain jane" sealed construction. We are researching if they were originally built with a gas blanket. From what I have found R-Temp did not require a gas blanket.

 

[RRaghunath]

From what I remember, R-Temp is a synthetic fluid with high flash / fire point making it safer for use in indoor transformers.

The fluid is hygroscopic like the mineral transformer oil and requires protection against absorption from atmosphere just like the mineral counter part.

The difference lies in that the moisture coupled with oxygen in air cause rapid deterioration in the properties of the mineral oil whereas the same is not so much of a concern in case of R-Temp (though the moisture will cause reduction in the BDV and is important).