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Composite Hollow Insulator

Composite hollow insulator is a hollow-core insulation component used inside high-voltage equipment, not on overhead lines. Defined in IEC 61462:2023, it combines a resin-impregnated fiber load-bearing tube, an elastomeric housing such as silicone rubber, and metal end fittings, and it can be used in both unpressurized and gas-pressurized designs for indoor and outdoor apparatus above 1,000 V AC or 1,500 V DC. It is widely applied in circuit breakers, disconnectors, transformers, bushings, surge arresters, GIS, and related compact substation equipment, where it must provide both mechanical support and external insulation while allowing internal space. Buyers typically evaluate internal diameter, creepage distance, fitting design, sealing, and pollution performance, while modern products are valued for light weight, reliability, and easier handling than ceramic alternatives.

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Product Accessories

End flanges / metal fixing devices for secure attachment to apparatus housings and terminals are part of the hollow insulator design itself and are commonly supplied in aluminum alloy or other metal constructions.

Corona rings / grading rings are used on higher-voltage assemblies to control electric-field stress at the shed and flange transition areas; some utility specifications require them above 220 kV, and on both ends above 500 kV.

Sealing and interface hardware is used for pressurized or sealed equipment arrangements, including the parts needed to keep the hollow core integrated correctly with the apparatus enclosure. IEC 61462 explicitly recognizes pressurized and unpressurized use, so sealing is part of the practical system package.

Mounting and connection hardware such as support brackets, bolts, nuts, and coupling interfaces are typically selected to match the target equipment and flange pattern. Manufacturer catalogs emphasize that the exact end-fitting arrangement is tailored to the customer’s application.

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Product Specifications

Product type

Composite hollow insulator for high-voltage electrical equipment.

Standard

IEC 61462:2023 / EN IEC 61462 for definitions, test methods, acceptance criteria, and design recommendations.

Service type

Available in unpressurized and permanently gas-pressurized designs.

Voltage scope

Intended for equipment above 1,000 V AC and above 1,500 V DC.

Typical product range

Manufacturer portfolios for composite hollow core insulators extend up to 1,100 kV AC and 800 kV DC.

Core material

Load-bearing tube made of resin-impregnated fibres / glass-fiber reinforced resin.

Housing material

Elastomeric housing, commonly silicone rubber or ethylene-propylene.

End fittings

Metal fixing devices / aluminum alloy flanges at the ends of the insulating tube.

Published geometric range

Example series show internal cover diameters from 80 mm to 350 mm, cover heights from 433 mm to 4,790 mm, and creepage distances from 628 mm to 22,310 mm.

Application environment

Suitable for outdoor and indoor equipment; one published source also highlights use in pollution degree zones I–IV and in seismic hazard areas.

Product Applications

Economy is more affordable

where the hollow core supports the switching apparatus and helps keep the insulation system compact. IEC explicitly includes HV circuit-breakers and manufacturers list live tank breakers, dead tank breakers, and GIS among common applications.

GIS and compact substation breakers
in high-voltage bays, where the insulator must combine structural support with reliable external insulation.

Disconnectors, switch-disconnectors, and earthing switches
that need a hollow insulated support or enclosure section inside a high-voltage apparatus layout.

Instrument transformers and power transformers
where the hollow composite body serves as the external insulating cover or enclosure component.

Cable terminations, bushings, and surge arrester housings

Product Advantages

Lower weight and easier handling

Composite hollow designs are repeatedly described as lighter than ceramic alternatives, which helps with transport, installation, and structural loading.

Strong outdoor performance

Silicone-based housings provide hydrophobicity, UV resistance, and good behavior in polluted or wet environments, which is a major reason these products are chosen for exposed substations.

Application flexibility

The same core technology can be tailored for breakers, transformers, GIS, bushings, cable terminations, and surge arrester housings, with geometry and fittings matched to the project.

WellDone Composite hollow insulator Plan Drawing

FAQ

What is a Composite Hollow Insulator used for?

It is used in high-voltage equipment to provide insulation and mechanical support in a compact hollow-core design.
Where is it typically installed?

It is commonly used in circuit breakers, disconnectors, transformers, bushings, and GIS equipment.
Why choose a composite hollow design?

It is lighter than ceramic, easier to handle, and performs well in outdoor and polluted environments.