Compatibility studies of B-staged polyester film with insulating oil for application in transformer coils

In transformers, paper insulated coils are used. These coils are immersed in mineral insulating oil which acts both as an insulant and coolant. During a short-circuit in the system, these coils are subjected to large electro-dynamic stresses, resulting in misshaping of the coils because of poor bonding between the turns of paper and oil insulation. To overcome this difficulty a B-staged polyester film tape having a bond on both sides has been developed. Conductors wound with this adhesive polyester film tape can have better bonding between the turns and can also withstand electro-dynamic forces without becoming misshaped. Studies have revealed that the developed tape is perfectly compatible with the transformer oil. Hence, it is concluded that the double side bond B-staged adhesive polyester film tape can be used in transformers for their better withstandability against large electro-dynamic forces.