KNAN is a transformer that uses less flammable non-mineral oil such as silicone oil, synthetic ester or natural ester (FR3) as the insulating fluid with natural air convection cooling. KNAF has same transformer oil as KNAN but with external forced air cooling.
Traditionally transformers have used mineral oils, but industry has now acknowledged the drawbacks of traditional mineral oil namely- flammability, poor biodegradability, low moisture tolerance and corrosive Sulphur.
Transformer ester oils (non-mineral oils) can be classified in to two groups- Synthetic and Natural.
Synthetic esters are manufactured from raw materials and additives are added to tailor its performance to a specific application (such as cold climates).
Natural esters are made from renewable materials such as canola, soybean etc.
A common non-mineral oil used in KNAN/KNAF transformers is FR3 which is formulated from edible vegetable oil along with performance enhancing materials. It does not contain petroleum, halogens or other harmful materials. FR3 has exceptionally high ignition point of 3600C and flash point of 3300C.
Advantages of using non-mineral oil
KNAN/KNAF transformers uses insulating non-mineral oil that has higher fire point (>3000C) compared to regular mineral oils (Symbol starts with ‘O’) used on typical oil filled transformers classified as ONAN/ONAF etc. Non-Mineral oil also increases insulation life of transformer, is more environmentally friendly, is non-toxic, less flammable. Transformers that are required to be installed in explosive areas uses non-mineral oil due to its high ignition point.
Disadvantages of using non-mineral oil
Non-mineral oil such as FR3 is more expensive compared to traditional transformer mineral insulating oil. Due to lower heat dissipation by non-mineral oil compared to traditional mineral oils, transformer of same kVA will have larger external tank dimensions in KNAN/KNAF design compared to ONAN/ONAF design.
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Click to read additional info on FR3 transformer insulating fluid.