Transformer ester oil vs mineral differences?

[JamesM]

I'm looking at a transformer assembly job, the transformer is from Siemens and is insulated with Ester oil. I've only worked with Mineral oil before, are there any differences in the way we should handle the Ester oil?

My initial thoughts would be new pump and hoses so as not to contaminate with the mineral oil residue in our existing equipment.

I've read that the ester oil is not affected by moisture/water ingress, does that mean a nitrogen blanket is not required? I feel like Nitrogen or dry air still makes sense but just wanting to clarify if any one has some experience with this product.

Thanks

[Kalbi_Rob]

I'm looking at a transformer assembly job, the transformer is from Siemens and is insulated with Ester oil. I've only worked with Mineral oil before, are there any differences in the way we should handle the Ester oil?

My initial thoughts would be new pump and hoses so as not to contaminate with the mineral oil residue in our existing equipment.

I've read that the ester oil is not affected by moisture/water ingress, does that mean a nitrogen blanket is not required? I feel like Nitrogen or dry air still makes sense but just wanting to clarify if any one has some experience with this product.

Thanks

First question would be is it Synthetic or Natural Ester Fluid?

https://www.midel.com/blog/about-esters/

Synthetic esters are manufactured from carefully selected raw materials to give a finished product that is tailored to the specific application. In the case of MIDEL 7131 it has been developed specifically to be used as a transformer dielectric; hence it is a high performance fluid which is suitable for use in all types of application. Crucially, MIDEL 7131 has a very low pour point and excellent oxidation stability, making it suitable for cold climates and breathing systems where the fluid is exposed to oxygen from the air.

Natural esters are made from renewable natural sources, for example MIDEL eN 1204 (rapeseed/canola) and MIDEL eN 1215 (soybean). The base oil is chosen to give the best possible fit to the application; however unlike synthetic esters the properties of these base oils cannot be significantly altered. Therefore in order to get a natural ester dielectric fluid that remains liquid at low temperatures a compromise has to be made, and a base oil with reduced oxidation stability is usually chosen. This means that natural esters are only suitable for sealed equipment. Natural esters also have high pour points when compared to synthetic esters, and so are best suited to temperate locations or indoor applications.

FR3 would also be a form of Natural Esters.

https://www.cargill.com/bioindustrial/envirotemp/fr3

[mbaxter1]

I'm looking at a transformer assembly job, the transformer is from Siemens and is insulated with Ester oil. I've only worked with Mineral oil before, are there any differences in the way we should handle the Ester oil?

My initial thoughts would be new pump and hoses so as not to contaminate with the mineral oil residue in our existing equipment.

I've read that the ester oil is not affected by moisture/water ingress, does that mean a nitrogen blanket is not required? I feel like Nitrogen or dry air still makes sense but just wanting to clarify if any one has some experience with this product.

Thanks

i like to use new hoses when working with different oil. i would put a nitrogen blanket for good practice.

[Nick1234]

I'm looking at a transformer assembly job, the transformer is from Siemens and is insulated with Ester oil. I've only worked with Mineral oil before, are there any differences in the way we should handle the Ester oil?

My initial thoughts would be new pump and hoses so as not to contaminate with the mineral oil residue in our existing equipment.

I've read that the ester oil is not affected by moisture/water ingress, does that mean a nitrogen blanket is not required? I feel like Nitrogen or dry air still makes sense but just wanting to clarify if any one has some experience with this product.

Thanks

Ester oil is still affected by moisture/water ingress it just has a much higher tolerance for moisture ~100x higher then that of mineral oil. It also seems to not be effected by stratification if mixed with other transformer insulation oils.
In general the difference between the 2 transformers design wise is that ester oil requires more cooling fins and they need a different type of gaskets over mineral oil as ester oil tens to suck the moisture out of the air more readily then mineral oil.

[bbryant]

I'm looking at a transformer assembly job, the transformer is from Siemens and is insulated with Ester oil. I've only worked with Mineral oil before, are there any differences in the way we should handle the Ester oil?

My initial thoughts would be new pump and hoses so as not to contaminate with the mineral oil residue in our existing equipment.

I've read that the ester oil is not affected by moisture/water ingress, does that mean a nitrogen blanket is not required? I feel like Nitrogen or dry air still makes sense but just wanting to clarify if any one has some experience with this product.

Thanks

As a general practice we use different hoses and pumps for each type of oil we work with. I also apply a nitrogen blanket to every transformer when possible.