INSULATING PAPER – A CORE MATERMINING TRANSFORMER SAFETY

In the structure of a transformer, there are materials that are not easily visible but play a vital role in the performance and service life of the equipment. Insulating paper is one of the most critical components, responsible for electrical insulation, thermal insulation, and protection of the winding system throughout operation.

What Is Insulating Paper?

Insulating paper is an electrical insulating material made from high-purity cellulose fibers, typically derived from natural wood. It undergoes a strict manufacturing and processing process to ensure:

High purity
High dielectric strength
Stable mechanical and thermal performance

In transformers, insulating paper is commonly impregnated with insulating oil, forming an oil–paper insulation system that significantly enhances dielectric strength and heat dissipation.

The Role of Insulating Paper in Transformers

Insulating paper is not merely an auxiliary material; it plays a decisive role in the entire transformer system:

Insulation Between Windings

Prevents electrical discharge and short circuits between high-voltage and low-voltage windings, ensuring safe operation.

Insulation Between Windings and the Core

Maintains a stable electric field inside the transformer and minimizes energy losses.

Improved Mechanical Strength

Helps secure the windings, reducing vibration during heavy load operation or short-circuit events.

Extended Transformer Service Life

The quality of insulating paper directly affects the overall insulation lifespan, a key factor in determining the transformer’s durability.

Common Types of Transformer Insulating Paper

Several types of insulating paper are widely used in transformer manufacturing:

Kraft Insulating Paper

Most commonly used in oil-immersed transformers
Excellent oil absorption capability
Cost-effective and highly efficient

Pressboard Insulation

Greater thickness and high mechanical strength
Used for insulating tubes, barriers, spacers, and winding supports

High-Temperature Resistant Insulating Paper

Suitable for high-capacity transformers
Designed to operate reliably under high temperatures and heavy loads

Technical Standards for Transformer Insulating Paper

Insulating paper used in transformers must comply with strict international standards, such as:

IEC 60554
IEC 60641
Equivalent ISO / ASTM standards

Key technical parameters include:

Dielectric strength
Tensile strength
Ash content
Moisture content
Long-term thermal endurance

Using non-standard or low-quality insulating paper can lead to insulation degradation, partial discharge, and serious transformer failures.

Impact of Insulating Paper on Transformer Quality

In practice, many transformer failures after long-term operation are closely related to aging of the insulation system. Therefore:

High-quality insulating paper helps reduce the risk of failures
Ensures stable performance during continuous operation
Lowers long-term maintenance and repair costs

CTC – A Strong Focus on Insulating Materials in Every Transformer

At Hanoi Electrical Equipment and Transformer Manufacturing Joint Stock Company (CTC), insulating paper is:

Carefully selected from reputable suppliers
Strictly controlled in terms of origin and quality standards
Processed and installed according to rigorous technical procedures

We believe that transformer quality lies not only in visible components, but also in every layer of insulation inside.

Conclusion

Insulating paper is the foundation of transformer safety, playing a crucial role in determining performance, reliability, and service life. Selecting the right type of insulating paper that meets technical standards is a fundamental requirement to ensure stable and long-lasting transformer operation.