How to choose the diamond size of Diamond Dotted Paper

What Is the Diamond Pattern Size in DDP? The “diamond pattern” refers to the heat-curable epoxy resin dots printed o...

What Is the Diamond Pattern Size in DDP?

The “diamond pattern” refers to the heat-curable epoxy resin dots printed on the surface of Diamond Dotted Paper in a diamond-shaped grid.
The diamond size typically refers to the side length or diagonal of a single diamond, such as 4mm, 6mm, 9mm, 12.5mm, or 20mm.

Performance Comparison of Different Diamond Sizes

Diamond Size	Dot Density	Bonding Strength	Air/Varnish Permeability	Typical Applications
Small (4mm~6mm)	High	Strong	Poor	Small dry-type transformers, high bonding areas
Medium (9mm~12.5mm)	Moderate	Medium	Fair	General transformer insulation
Large (20mm and above)	Low	Low	Excellent	Large oil-immersed transformers with better oil flow and cooling needs

How to Choose the Diamond Size?

1. Based on Transformer Type:

Transformer Type	Recommended Diamond Size
Dry-type transformer	9mm~12.5mm (medium)
Oil-immersed transformer	≥12.5mm (large)
Control transformer / low power coils	4mm~6mm (small)

2.Based on Performance Needs:

Application Focus	Suggested Diamond Size	Reason
Strong bonding strength	Small (4~6mm)	Dense dot distribution ensures solid structure
Better oil/air circulation	Large (12.5~20mm)	Sparse dots allow better oil/gas flow
General-purpose use	Medium (9~12.5mm)	Balanced performance, widely used

Common Diamond Size Examples

Diamond Size	Application
4×4 mm	Tight bonding for small coils
9×9 mm	Standard dry-type transformer insulation
12.5×12.5 mm	For oil-immersed transformers—balanced bonding and ventilation
20×20 mm	For large oil-immersed units—enhanced oil channeling and cooling

Summary of Selection Recommendations:

Dry-type transformer → 9mm or 12.5mm

Oil-immersed transformer → 12.5mm or larger

Compact space / high structural strength → 4mm or 6mm

To sum up:

If the structural requirements are high, choose small diamonds; if the thermal management and oil flow requirements are high, choose large diamonds; for general use, choose medium (such as 9mm) specifications.

XUJUE ELECTRICAL is a professional manufacturer of electrical insulation materials with 65 years of experience in insulation material production. If you tell me the specific transformer type, voltage level and use location, we can recommend more accurate specifications.