Heat-Resistant DDP Insulation Paper

Heat-resistant DDP insulation paper is one of the most widely used composite insulation materials in oil-immersed transformers and plays a vital role in ensuring the safe operation of power equipment. With the continuous development of power grid construction, the commissioning of new energy projects, and the upgrading of distribution systems, the performance, reliability, and stability requirements for heat-resistant DDP insulation paper continue to rise. This article analyzes its material structure, performance features, typical applications, and key selection considerations to help you better understand this insulation material.

What Is Heat-Resistant DDP Insulation Paper?

DDP stands for Diamond Dotted Paper. It is produced by coating one or both sides of electrical insulation paper with a thermosetting epoxy resin, followed by a high-temperature pre-curing process. Heat-resistant DDP insulation paper is an upgraded product with a temperature resistance rating of 105°C–120°C or higher. It is suitable for high-temperature and heavy-load working conditions in oil-immersed transformers.

Core Features and Advantages

1. Heat Resistance

Base paper made from high-temperature fibers such as aramid and polyimide mixed pulp

Enhanced thermal stability through special resin impregnation

Maintains high insulation resistance and dielectric strength under elevated temperatures

2. Electrical Insulation Performance

High dielectric strength

Low dielectric loss. This reduces energy loss during equipment operation.

Stable permittivity. This ensures operational stability of electrical equipment.

3. Mechanical Properties

High tensile strength and tear resistance

4. Good Flexibility and Processability

Excellent puncture resistance and wear resistance

Suitable for automatic winding processes

5. Environmental Adaptability

Excellent oil resistance for oil-immersed equipment

Moisture-resistant and chemically resistant

Compliant with environmental standards such as RoHS and REACH

Typical Applications of Heat-Resistant DDP Insulation Paper

Heat-resistant DDP insulation paper is mainly used for internal insulation in oil-immersed transformers and oil-immersed reactors. Specific application scenarios include:

Inter-layer insulation of coils

Turn-to-turn insulation

End insulation pads

Wire-wrapping insulation

Auxiliary insulation for core clamps and support components

This material is suitable for complex conditions involving high temperature, heavy load, and high humidity. Typical application scenarios include:

New energy power stations such as photovoltaic (PV) and wind power

Distribution systems in industrial and mining enterprises

Substations in high-altitude regions

Compact, high-load urban distribution networks

Key Selection Considerations for Heat-Resistant DDP Insulation Paper

When selecting heat-resistant DDP insulation paper, the following principles should be followed:

Confirm the Temperature Class

Match the product’s temperature rating with the transformer design, such as Class E, F, or H.

Check Resin Dot Quality

Inspect the uniformity and fullness of the diamond-shaped resin dots to prevent insufficient bonding or unstable performance due to uneven resin distribution.

Verify Base Material Performance

Prefer products using high-density electrical insulation paper with stable electrical properties as the base material.

Review Test Reports

Require suppliers to provide test reports including the following indicators, compliant with IEC, GB/T, and other industry standards:

Dielectric strength

Bonding strength

Moisture content

Thermal aging test data

Match the Application Environment

Allow sufficient insulation margin for high-altitude applications

Choose low-hygroscopicity products for high-humidity environments

Use high-bonding, high-heat-resistant models for large-capacity transformers

Installation and Usage Precautions

♦ Storage Conditions: Heat-resistant DDP insulation paper should be stored in a dry environment. And it is recommended that relative humidity be below 60% and direct sunlight be avoided.

♦ Processing: During cutting or punching, keep tools clean to prevent contamination of the material.

♦ Installation Process: Avoid excessive bending or stretching during installation to prevent mechanical damage.

♦ Compatibility Testing: Before use, conduct compatibility tests with varnish and insulating oil.

FAQs

Q1: What is the main difference between DDP insulation paper and ordinary insulation paper?

A1: DDP insulation paper undergoes densification treatment, giving it higher density than ordinary insulation paper. Its electrical performance and mechanical strength are significantly improved, making it suitable for high-voltage and high-frequency equipment.

Q2: How can I tell if the insulation paper needs to be replaced?

A2: Regularly measure insulation resistance and perform dielectric loss angle tests. If the measured values drop more than 30% from the initial values, or if the material shows signs of brittleness or discoloration, replacement should be considered.