A Transformer board is a type of paperboard with high basis weight made from low conductive cellulose. Transformer board serves as an insulating layer for electrical transformers since 1940’s.
Since the invention of high voltage electrical transformers, there has always been a need for an insulating material that could withstand high electrical and physical stresses exerted on core and windings.
In the earlier times, Press board, a board made by compressing layers of recycled paper or cotton waste together and drying them, has been used for isolation applications. Nevertheless as electrical industry developed, the need for a higher density material that was able to insulating larger and higher voltage transformers grew. This requirement from industry made board manufacturers to search for alternatives, and enabled the manufacture of transformer board.
Unlike pressboard production, Transformer board is not based on used paper or cotton waste but is made with electrical grade sulfate cellulose. Transformer board is manufactured from pure cellulose (virgin fibers) without a resin or binder, improving electrical insulation capabilities and can be completely dried, degassed, and oil impregnated. Today, new methods of production replaced almost all insulating parts of transformers with parts made from transformer board.