Ester or synthetic oil transformers

Ester or synthetic oil transformers are becoming popular at lower MVA and voltages• Quite common at 132 kV. Have been manufactured as high as 220kV and 400 kV in Europe.• Dielectric properties are not as good as mineral oil therefore larger clearance need inside tank.• Heat transfer characteristics is not as good as mineral oil therefore larger cooler required• The Ester or synthetic oil itself is significantly more expensive than mineral oil , usually 3~4 times• Transformers designed for mineral oil should not really be retrofitted with synthetic oil, for ester oil,transformer active part, such as, structures of winding assembly shall be special considered.• In general, the higher permissible operating temperatures are not being taken advantage of on largetransformers. The same winding/oil rises are still used.• Oil optional for natural ester and synthetic is more environment friendly than mineral oil