Epoxy Fiberglass Filament-Wound Tubes for Transformer Core Winding Insulation

Fiberglass Filament-Wound Tubes for Transformer Insulat […]

Fiberglass Filament-Wound Tubes for Transformer Insulation

In the design and manufacture of transformers, especially dry-type transformers, special-purpose transformers, and reactors, fiberglass filament-wound tubes (typically epoxy fiberglass wound tubes) are used as electrical insulation between the iron core and copper windings. They serve as insulation cylinders while also providing structural support and electrical isolation.

1. Insulation Structural Design

From the innermost to the outermost layer, the insulation structure is typically arranged as follows:

Iron Core (Grounded Body):
The silicon steel sheet core is located at the center of the magnetic circuit and is normally grounded at a designated point according to the transformer design.

Air Ducts and Insulation Spacers (Optional):
Insulation spacers, such as laminated fiberglass sheets or epoxy blocks, may be placed adjacent to the core to create cooling air ducts and maintain the required clearances.

Fiberglass Filament-Wound Tube (Main Insulation Cylinder):
Installed around the core or its supporting structure, the tube provides solid electrical insulation between the core and the windings, as specified by the transformer insulation design.

Copper Windings (Energized Components):
The copper windings are arranged around the insulation tube, with additional insulation or cooling ducts where required by the design.

2. Key Advantages of Fiberglass Wound Tubes for Transformer Insulation

High Dielectric Strength:
Epoxy resin reinforced with E-glass fibers provides excellent dielectric properties. The actual dielectric strength depends on the resin system, fiber architecture, wall thickness, manufacturing quality, and test conditions. The material can be designed to withstand the electrical stresses specified for the transformer.

Excellent Thermal Resistance:
Depending on the resin system and material qualification, fiberglass wound tubes can be designed for applications associated with Class F (155°C) or Class H (180°C) insulation systems. The suitability of the tube should be verified against the required thermal performance and operating conditions.

High Mechanical Strength:
Fiberglass-reinforced epoxy tubes provide mechanical strength and dimensional stability. They can support winding structures and help resist the mechanical forces generated during operation and short-circuit events when properly designed and installed.

3. Key Technical Considerations for Electrical Insulation

Partial Discharge Control:
The manufacturing process should minimize voids, delamination, and impurities within the insulation. Air voids in solid insulation can cause localized electrical stress and partial discharge, potentially leading to insulation deterioration and eventual failure.

Electrical Clearance and Creepage Distance:
In addition to the radial wall thickness of the tube, the extension of the tube beyond the winding ends and the required creepage distances must be determined according to the operating voltage, insulation coordination, environmental conditions, and applicable standards. These factors help prevent surface discharge and flashover.

Core Grounding and Potential Control:
The transformer core grounding arrangement must follow the approved electrical design. Insulation tubes should be protected from sharp edges, burrs, and contaminants during assembly. The insulation structure must also maintain the required dielectric separation and prevent unintended conductive paths.

Moisture Resistance and Surface Protection:
Fiberglass-reinforced epoxy tubes generally offer good moisture resistance. However, surface contamination and moisture can reduce surface insulation resistance under humid conditions. Where required by the application, a compatible insulating varnish or other approved surface treatment may be applied.

Contact Fiberglass Filament-Wound Tubes Manufacturer

Xujue Electrical is a professional manufacturer of electrical insulation materials for transformers, with over 65 years of manufacturing experience. We specialize in providing reliable insulation material solutions for transformers and other electrical equipment.

We supply high-quality fiberglass filament-wound tubes and can also manufacture customized tubes and precision-machined insulation components according to different transformer applications, voltage requirements, dimensions, and mechanical performance specifications. Our flexible customization services help meet the specific requirements of different customers and applications.

We offer free samples for testing , allowing customers to evaluate material properties and verify product suitability for their applications. Our goal is to provide reliable insulation solutions that support transformer design and manufacturing.

Contact us today for technical data, customized solutions, and free sample inquiries.