Diamond Dotted Insulation Paper cable paper

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Product Details

It is also known as DDP. The use of this B-stage resin coated paper increases the short circuit strength of distribution transformer coils. 

It is produced by coating modified epoxy resin in diamond dot patterns on electrical insulating paper. The size of the dots are carefully designed to avoid interfering with vacuum drying and oil impregnation. 

This type of presspaper is treated chemically and included nitrogen content to get a upgraded thermo performance.

Product Introduction

DDP elecrical insulation paper in oil transformer hecheng

Product Parameters


• Insulation class A (105 °C) 
• Presspaper (in rolls), 100 % sulphate wood pulp
• High purity and mechanical strength
• Thermosetting coating of expoxi-phenolic resin (B-stage), put in rhombic pattern on one or both sides.
• Good compatibility with transformer impregnants after curing of the coating.
Note: The surfaces to be bonded must remain tightly pressed together during curing


• Layer insulation in liquid-immersed transformers


• In rolls. 1000 mm, 1220mm, 1320mm, 1500mm, 1700mm, 1900mm

• In strips minimum width 4 mm
• Available thickness: 0.05 - 1.0 mm (presspaper thickness)


Nominal Thicknessmm0.
Thickness Tolerancemm±0.005±0.007±0.01±0.01
Norminal Grammageg/㎡80±8115±11160±16240±24
Standard Widthmm1000mm

Tensile StrengthLengthwiseMpa≥75


Tear Strengthg≥50≥100≥150≥300
Breakdown VoltageKV≥0.8≥1.1≥1.4≥1.6
Bond StrengthKpa≥450

Moisture Content%4-8

Curing Temperature and Time90℃±5℃/3h or 130℃±5℃/6h

Storage Lifemonth6 months, room temperature, dry and well-ventilated environment

diamond dotted paper for transformer hecheng