Insulation Paper

Why Transformer Insulation Matters？

Transformer insulation paper is not just a material — it is a critical part of the insulation system that:

 

● Ensures high dielectric strength between windings and core

 

● Maintains thermal stability under load/temperature cycling

 

● Works with oil to prevent partial discharge and breakdown

 

● Affects transformer service life & reliability

 

AHA Insulation paper

AMA Insulation paper

DDP Insulation paper

DMD insulation paper

Electrical insulating paper

Epoxy prepreg DMD

Insulating crepe paper

Insulation crepe paper tube

Insulation fish paper

NHN insulation paper

NMN insulation paper

Oil duct strips

Transformer insulation paper performance varies by material type, thickness and application area.

Instead of one fixed value, engineers evaluate insulation paper based on performance ranges and system matching.

Key performance dimensions include:

Dielectric Strength

Depends on paper grade, thickness and oil impregnation condition

Thermal Endurance Class

Available for Class A / E / B / F applications depending on material selection

Oil Compatibility

Designed for stable oil absorption and low gas generation in oil-immersed systems

Moisture Control

Controlled moisture absorption to maintain dielectric stability during operation

Dimensional Consistency

Thickness tolerance and surface uniformity ensured by process control

Our engineers recommend suitable grades based on transformer design drawings and operating conditions.

Insulation System Integration

 

Insulation Paper in the Transformer Insulation System

Transformer insulation system consists of:

Insulation Paper

Pressboard / Composite materials

Slot liners / Wedges

End-turn insulation

Barrier insulation

Choosing the right combination ensures:

 Optimal dielectric field distribution

 Low partial discharge risk

 Long operating life

● Wide range of thickness & material types   ● High dielectric & thermal performance   ● Excellent oil absorption & compatibility

● IEC / ASTM / International standards support   ● Customizable based on drawings & specs   ● Stable batch supply for project delivery

● Engineering support & documentation

● Incoming Raw Material Inspection  ● Thickness & Dielectric Tests

● Oil Compatibility & Absorption Test   ● Thermal Aging & Dimensional Stability   ● Batch Final Inspection & Traceabilit

About Weshare

 

 

Who are we?
Weshare is a professional manufacturing vendor with 20 vears of experience. Weshare is a leading Chinese manufacturer and exporter of transformer components, electrical insulation materials and consulting company.

 

Why should you buy from us not from other suppliers?
- We have vertical setup，so we can ensure price, quality and leadtime.
- We are manufacturing vendor and we invest 12% profit into R&D.
- We can make Time and Action Calendar 1 day after PO.
- We can give out CAP with 12 hours.
- We supply wide range of transformer components and insulation materials.
- We have a team with 20 years of experience to serve our customers.

Why should you buy from us not from other suppliers?

Electrical Insulation Paper

Insulation Crepe Paper

Composite Insulation Paper

Insulation Pressboard

The products are exported to East of Asia, North of Europe ,The Mid East, South of American, Egypt and East of Africa，and are matched by more than

600 domestic transformer and transformer manufacturers, and are well received by users at home and abroad

Electrical insulation paper
Electrical insulation paper is an electrical insulation material made by adding an insulating coating to paper pulp. It has good insulation properties, mechanical strength, and temperature resistance. Paper insulation material is a thin sheet-like insulating material made of plant fibers, mineral fibers, synthetic fibers, and mixtures as raw materials, and the fibers are deposited on a paper machine through a medium

 

Electrical insulation paper advantages
Protection from shocks:：
Electrical insulation paper protects you from shocks and other electrical conductivity

 

Reduced risk of short circuits:
Electrical insulation paper helps ensure equipment functions safely and reliably by reducing the risk of short circuits and leakage

 

Resistant to extreme temperatures:
Some electrical insulation paper can withstand temperatures up to 3,000°F (1,600°C)

 

Chemical resistant:
Some electrical insulation paper can resist hostile environments and corrosive substances

Process of electrical insulation paper

01

 

Pulp preparation

First, the raw wood is processed to peel off impurities such as bark, branches, and leaves, and then the wood is cut into small pieces and put into the processing machine. After a series of processes such as beating and screening, the pulp is obtained.

02

 

Pulp conditioning

Send the pulp into a large vat for stirring, and control the humidity, PH value, screening, and other parameters of the pulp to make the pulp quality more stable.

03

 

Mechanical sizing

The pulp is made into paper form through mechanical devices such as gauze and rollers, and glue is added during the production process to make the surface of the insulating paper have better flatness and mechanical strength.

04

 

Drying processing

Send paper with high humidity into a high-temperature drying chamber for dehydration and drying processing to control the moisture content of the paper within a reasonable range and avoid deformation and damage of the paper due to excessive moisture.

05

 

Reeling and packaging

The insulating paper will be rolled, cut and other processes, then packaged and stored for use.

Application

Insulation Crepe Paper

Electrical Grade Insulation Crepe is a type of insulating paper, which is reprocessed from cable paper made of sulfate pulp. It has very good electrical properties in oil, showing a high average breakdown voltage and a small tangent value of the dielectric loss angle. Crepe paper is mainly used for wrapping the outgoing wires of transformers.

Electrical Insulating Crepe Paper Tube

The crepe paper tube is crafted from imported Miki crepe paper, and primarily serving as flexible crepe paper bushings for high-voltage and low-voltage taps within the body of oil-immersed transformers, as well as for the external insulation of screw connections. It exhibits remarkable flexibility, ensuring it does not break even when bent in any direction.

Composite Insulation Paper

The main products include 6520 green composite insulating paper, 6630DMD insulating paper, 6641DMD insulating paper, 6640NMN insulating paper,6650NHN insulation paper and other flexible insulation papers

DDP Application

Insulation Pressboard

nsulation pressboard is produced from pure unbleached cellulose taken from long-fibered coniferous wood and manufactured by Weshare. Due to the high chemical purity, mechanical strength, and optimum oil impregnability, the pressboard is primarily used in oil-filled power transformers and distribution transformers and is suited as an insulation material for electric machines and capacitors.

During the use of insulating paper, under the long-term influence of external environmental factors, a series of chemical and physical changes will occur, resulting in a gradual decrease in mechanical and electrical properties. This process is called insulation aging of insulating paper. The main forms of insulation aging of insulating paper are: Electrical aging, thermal aging, mechanical aging, moisture-induced aging, etc.
Electrical aging
Electrical aging is an inevitable form of aging for all high-voltage equipment. The insulating paper used in transformers is bound to be affected by electrical aging. In the oil-paper structure, the pores between the fibers of the insulating paper are impregnated with oil, but during the manufacturing process, the internal There will be more or less air gap defects at micro scale or even macro scale. When the external electric field reaches the initial discharge voltage of the air gap, partial discharge will occur, destroying the structure of the insulating paper and gradually reducing its insulation performance.
Heat aging
High-voltage equipment will generate a certain amount of heat during operation. At such higher temperatures, the insulating paper will undergo chemical reactions such as thermal cracking and oxidative cracking, resulting in a decrease in its mechanical and electrical properties.
Mechanical aging
The mechanical stress on insulating paper comes from mechanical forces, temperature changes, electric field forces, etc. When the insulating paper is subjected to mechanical stress, its mechanical properties will be irreversibly reduced until cracks or air gaps occur, leading to partial discharge. This phenomenon is called mechanical aging. During the production and operation of transformers, insulating paper will be subjected to various stresses at the same time, so the mechanical aging of insulating paper is an aspect of insulation aging that cannot be ignored.
Moisture promotes aging
The influence of moisture on insulating paper is that it can directly participate in the degradation reaction of cellulose, accelerating the degradation and aging of insulating paper. When the cellulose molecular chain degrades, it also produces a part of water, which in turn accelerates the degradation of cellulose, thus producing more Too much moisture will create a vicious cycle and accelerate the degradation of cellulose; at the same time, moisture will increase the conductivity of the insulating paper, increase the dielectric loss, and the breakdown strength of the insulating paper will drop sharply. This accelerates the insulation aging of the insulation paper.
The presence of moisture in the oil-paper insulation structure of the transformer is caused by poor vacuum drying during the manufacturing process, moisture absorption by the insulation paper during assembly, or moisture caused by improper maintenance during transportation and storage. Therefore, the presence of moisture will pose a threat to the operation of the transformer and may cause accidents in severe cases.

Insulating paper fiber material is the most important insulating component material in oil-immersed transformers. Paper fiber is the basic solid tissue component of plants. The atoms that make up material molecules have positively charged nuclei and negatively charged electrons orbiting the nuclei. They are similar to metals. The difference between conductors is that there are almost no free electrons in insulating materials. The very small conductivity current in insulators mainly comes from ionic conductance. Cellulose is composed of carbon, hydrogen and oxygen. Due to the presence of hydroxyl radicals in the molecular structure of cellulose, there is the potential to form water, making the paper fiber water-containing. In addition, these hydroxyl radicals can be considered as centers surrounded by various polar molecules (such as acids and water). They are combined with hydrogen bonds, making the fiber susceptible to damage: at the same time, the fiber often contains a certain proportion (about 7% (left and right) impurities, these impurities include a certain amount of moisture. Due to the colloidal nature of the fiber, this moisture cannot be completely removed. This also affects the performance of paper fiber

As one of the leading insulation paper suppliers in China, we warmly welcome you to wholesale high-grade insulation paper made in China here from our factory. All our products are with high quality and competitive price.