Phenolic Paper Tube Solutions for Transformer Insulation

1. Introduction to Phenolic Paper Tube Phenolic paper tube is a thermosetting insulating tube made of high-strength ...

1. Introduction to Phenolic Paper Tube

Phenolic paper tube is a thermosetting insulating tube made of high-strength electrical insulating paper impregnated with phenolic resin and cured under heat and pressure. It offers excellent electrical insulation, mechanical strength, and heat resistance, making it one of the most commonly used insulation components in transformers, motors, and other electrical equipment.

2. Main Applications in Transformers

Inside a transformer, phenolic paper tubes play crucial roles in electrical insulation, mechanical support, and lead protection. Common applications include:

Coil Insulation and Phase Separation
Phenolic paper tubes are used between high- and low-voltage windings or between coil layers to provide electrical isolation, prevent discharge or short circuits, and ensure operational safety.

Lead Protection Tubes
They serve as protective sleeves for internal transformer conductors, preventing abrasion and insulation damage when wires pass through the iron core or tank wall. Especially in oil-immersed transformers, the tubes can remain stable and non-degradable even after long-term oil immersion.

Structural Support and Positioning
At the winding ends or between clamping structures, phenolic paper tubes act as support and positioning components to maintain mechanical stability and prevent coil displacement.

Insulating Components in Oil-Immersed Transformers
With excellent oil resistance, moisture resistance, and heat endurance, phenolic paper tubes are widely used in oil-immersed power transformers, distribution transformers, and current transformers.

3. Product Performance Characteristics

4. Selection and Customization

ZTelec Electric offers phenolic paper tubes in various sizes, thicknesses, and thermal classes according to customer requirements.
Typical specifications:

Outer diameter: Φ10mm–Φ150mm

Length: 500mm–1000mm (customizable)

Thermal class: B / F
We also provide custom machining and complete insulation system solutions for transformer applications.

5. Conclusion

As a key insulating component in transformers, phenolic paper tubes combine electrical safety, mechanical reliability, and cost-effectiveness. Thanks to their excellent thermal and oil resistance, they are widely applied in both oil-immersed and dry-type transformers.
As a leading manufacturer of electrical insulation materials in China, ZTelec Electric provides a full range of products including phenolic paper tubes, epoxy glass cloth tubes, DMD insulation paper, and aramid paper, serving global transformer and electrical equipment manufacturers with high-quality insulation solutions.