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Crepe paper tubes are a critical insulating material used in oil-immersed transformers. They are mainly applied for insulating, protecting, and mechanically supporting bare conductors inside the transformer.Compared with traditional phenolic paper tubes, crepe paper tubes have become the mainstream solution in this field due to their superior flexibility, electrical performance, and reliability. Below is an overview of their core applications and technical advantages in oil-immersed transformers.
This is the most important application of crepe paper tubes. They are tightly wrapped around bare conductors inside transformers, such as leads and winding connection points, forming a reliable insulation layer that prevents electrical breakdown between conductors or between conductors and ground.
In addition to electrical insulation, crepe paper tubes provide mechanical support for conductors, preventing displacement or deformation caused by vibration, transportation, or electromagnetic forces during short circuits. Their flexibility also allows them to adapt to conductor bending during installation and operation.
The unique creped structure gives the tube exceptional flexibility, allowing it to bend easily and fit tightly within the complex internal structure of transformers without cracking during bending.
After impregnation with transformer oil, the dielectric constant of the crepe paper tube becomes very close to that of transformer oil, effectively optimizing electric field distribution and significantly improving the overall electrical strength of the insulation system.
High Dielectric Strength:
For example, when the wall thickness (T) is ≥ 2 mm, the oil breakdown voltage can reach 35 kV.
Good Thermal Stability:
Typically rated as Class A insulation (105°C), with some products capable of higher thermal ratings.
Strong Chemical Compatibility:
Compatible with mineral oils, natural esters, varnishes, and adhesives, while also offering resistance to acids and alkalis.
Environmental Resistance:
Resistant to moisture and not easily damaged by insects, fungi, or mold.
Compared with conventional phenolic paper tubes, crepe paper tubes offer clear advantages including easier handling, higher reliability, and potentially lower overall system costs.
Standard products are manufactured within specified dimensions and performance ranges, while customized solutions can also be produced according to customer requirements.
Crepe paper tubes are produced by precisely winding multiple layers of electrical insulating crepe paper onto a mandrel, bonding them with compatible adhesives, and curing them to ensure structural strength, dimensional stability, and consistent performance.
Appearance requirements include uniform creping, clean edges, and freedom from impurities or damage. Performance testing must comply with relevant international and domestic standards such as IEC 60554 and GB 1094.
Automated technologies such as CNC tube winding machines and machine vision inspection systems are increasingly used in production, enabling higher dimensional accuracy (tolerances up to ±0.05 mm) and improved manufacturing efficiency.
In recent years, Chinese-made crepe paper products have achieved major technological breakthroughs and are now successfully used in 110 kV and even 500 kV power equipment.
In addition to traditional power transformers, specialized crepe paper tubes are being developed for new applications such as EV charging systems and railway traction transformers.
Although crepe paper tubes have excellent compatibility with mineral oils, studies show that compatibility with natural esters (vegetable oils) may vary. In some cases, the breakdown voltage in ester oils may be lower, requiring additional evaluation when designing insulation systems for ester-filled transformers.
Unused crepe paper tubes should be stored in a dry, clean, and well-ventilated environment, protected from compression, moisture, fire sources, and direct sunlight.
Since crepe paper tubes are mainly made from cellulose materials, they offer better biodegradability and environmental sustainability compared with certain synthetic insulation materials, aligning with green energy and sustainable development trends.
Crepe paper tubes are precision-engineered components and an essential part of oil-immersed transformer insulation systems. Combining electrical insulation, mechanical support, flexibility, and thermal stability, their continuous material and manufacturing advancements play a vital role in ensuring the safety and reliability of modern power systems.
