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Diamond Dotted Paper

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Senapathy Whiteley is a key supplier of high performance insulation materials, base and impregnated filter media to energy, automotive and industrial sectors globally.

Senapathy Whiteley is the flagship enterprise of the Senapathy Group and a pioneer manufacturer of insulation materials that are essential for the power supply and transformer industries.

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Symodot Diamond Dotted Presspaper

Electrical grade diamond dotted insulating press paper with thermostable 'B' stage epoxy resin on one side or both sides using a special process

Special Features of Symodot

SYMODOT can be used to electrically insulate and mechanically bond winding layers. Conductors, Laminations and Insulation layers.

The thermostable ‘B’ stage resin dots are applied in such way that enough space exists between them for Oil Impregnation. Normal coating of the Resin is about 10 Micron


Through the use of SYMODOT. the winding layers are stuck together and the complete windings become one solid block with considerable improvements in the short circuit strength of such windings.


SYMODOT is available in thicknesses of 0.08mm, and 0.175mm. 0.25mm and 0.325mm in rolls of width 914mm or 1000mm, and can also be supplied in any width. in multiples of 1000mm/914mm. SYMCDOT is normally wound on cardboard cores with a 76mm internal diameter.

Shelf Life

Shelf life-about one year, when stored at room temperature of 20°C and relative humidity 50%.

Distinguishing Factor

SYMODOT is distinguished by being a corona tree. This can be used in highly stressed areas in transformers.

The diamond squares are 9.5mm x 9.5mm and spaced 6.5 mm apart. These squares are arranged such that their diagonals lie parallel and perpendicular to the machine direction of the press paper and the diagonal of epoxy diamond coatings lie along a straight line. SYMODOT is track free at room temperature and curing after the process. provides rigid bonding.

Tensile Shear Strength Test

Tensile shear strength is determined on lapped bonded specimen. The test Specimen is prepared using two cleaned Aluminium or Copper sheet of thickness 0.5 to 1.0 mm, 150 mm long and 50 mm wide. Cut specimen of 50 mm X 50 mm size and place one over another carefully to form an overlap. Place the metal sheets over four layers of Epoxy Coated Paper so that the specimen shall form of size 50 mm X 50 mm as shown in the figures.

Sample specimen is then bonded at a pressure of 0.0138 Mpa (2PSI) and a temperature of 120°C for one hour. The bonded sample is tested for the shear strength with a pull rate of 150 mm/min(6 inches/min) at 100°C. The separation must occur in the paper layer and not due to the adhesion i.e.. the separation shall be of cohesive failure only.