EPGC203 G11 Epoxy Fiberglass Sheet Application in Dry Type Transformer Insulation Barrier

G11 epoxy fiberglass sheet is widely used as insulation barriers and support components in dry type transformers. Learn how G11 EPGC203 improves transformer insulation performan...

Application of G11 Epoxy Fiberglass Sheet in Dry Type Transformer Insulation Barriers

High-performance insulation materials improve the safety and reliability of dry type transformers

With the rapid development of renewable energy, power infrastructure, and smart grid systems, dry type transformers have become increasingly important in power distribution networks due to their advantages of fire safety, environmental friendliness, low maintenance requirements, and reliable operation.

In the manufacturing of dry type transformers, the insulation system is one of the most critical components determining the equipment’s service life and operational safety. Since transformers operate under the combined influence of electrical fields, heat, and mechanical stress for long periods, insulation materials must provide excellent electrical insulation performance, thermal resistance, mechanical strength, and dimensional stability.

As a high-performance electrical insulation material, EPGC203 G11 epoxy fiberglass sheet (G11 Epoxy Glass Laminate) is widely used in dry type transformers as insulation barriers, support components, and structural insulation parts, providing reliable protection for long-term transformer operation.

G11 Epoxy Fiberglass Sheet: A High-temperature Epoxy Glass Fabric Laminated Material

G11 epoxy fiberglass sheet is manufactured using high-strength alkali-free glass fiber cloth as the reinforcing material and high-temperature resistant epoxy resin as the bonding system. Through a high-temperature and high-pressure lamination process, it forms a rigid electrical insulation laminate with excellent mechanical and electrical properties.

Under international standards, G11 is commonly identified as:

NEMA G-11
EPGC203
IEC 60893 EPGC203
HGW2372.4

Among these standards, EPGC203 is the designation under the IEC 60893 standard system, while G11 is more commonly used in the NEMA standard system. Both materials have similar compositions and performance characteristics.

One of the most important advantages of G11 epoxy fiberglass sheet is its excellent thermal resistance. It can operate continuously at temperatures up to 155°C (Class F insulation grade).

Compared with standard G10 epoxy fiberglass sheet, G11 provides better mechanical strength retention and electrical stability under high-temperature conditions, making it more suitable for high-reliability electrical equipment such as dry type transformers.

The Important Role of G11 Epoxy Sheet as Insulation Barriers in Dry Type Transformers

A dry type transformer mainly consists of the iron core, high-voltage winding, low-voltage winding, insulation structures, and cooling system. During operation, the transformer generates heat while maintaining high electrical potential differences between windings. Therefore, reliable insulation structures are essential to ensure safe operation.

As an insulation barrier material, G11 epoxy fiberglass sheet is installed between transformer windings and critical insulation areas. Its main functions include improving insulation distance, reducing electric field concentration, and enhancing overall insulation reliability.

Improving insulation safety between windings

During transformer operation, sufficient insulation distance must be maintained between high-voltage and low-voltage windings to prevent electrical breakdown caused by excessive electric field stress.

G11 epoxy sheet has excellent dielectric properties and high insulation strength, allowing it to effectively separate windings with different voltage levels and improve the overall electrical safety of the transformer.

Reducing partial discharge risks

Partial discharge is one of the major factors affecting transformer service life. High-quality insulation materials must maintain stable dielectric performance under continuous electrical stress.

Due to its uniform structure and low water absorption, G11 epoxy fiberglass sheet maintains stable insulation performance during long-term operation, helping reduce the possibility of partial discharge and improving transformer reliability.

Providing mechanical support and structural protection

In addition to electrical insulation, transformer insulation components must also withstand mechanical stress.

During operation, transformer windings experience thermal expansion and contraction. In the event of short circuits, strong electromagnetic forces can also act on the winding structures. If insulation components lack sufficient mechanical strength, deformation or damage may occur.

G11 epoxy fiberglass sheet offers excellent bending strength and dimensional stability, making it suitable for:

• Coil support plates
• Insulation spacers
• End insulation components
• Structural support parts

These properties help maintain the stability of internal transformer structures.

Why Choose G11 Epoxy Fiberglass Sheet for Dry Type Transformers?

Compared with conventional insulation materials, dry type transformers require higher-performance insulation systems.

Although materials such as G10 epoxy fiberglass sheet provide good electrical insulation properties, their thermal resistance and mechanical retention at elevated temperatures are lower compared with G11.

The thermal performance comparison is shown below:

For Class F dry type transformer insulation systems, G11 provides better long-term performance and reliability.

Machining Forms of G11 Epoxy Sheet for Dry Type Transformers

According to different transformer designs, G11 epoxy fiberglass sheet can be processed into various insulation components, including:

Flat insulation barriers
Customized insulation plates
Coil support plates
Insulation spacers
End insulation components
CNC machined insulation parts

Through cutting, drilling, milling, and CNC machining processes, G11 can meet the customized structural requirements of different dry type transformers.

G11 Epoxy Fiberglass Sheet Supports the Development of High-reliability Insulation Systems

With the continuous growth of renewable energy, power electronics, and smart grid applications, dry type transformers are developing toward higher capacity, higher efficiency, and longer service life.

Future electrical equipment will require insulation materials with:

Higher thermal resistance
More stable electrical performance
Stronger mechanical reliability
Longer service life

Due to its excellent thermal resistance, electrical insulation properties, and machining performance, G11/EPGC203 epoxy fiberglass sheet will continue to play an important role in dry type transformers, high-voltage switchgear, motors, and renewable energy equipment