A reinforcement liner for tubular busbars is an insulating and mechanical support layer, typically made from fiber-reinforced plastics or specialized polymers, designed to enhance electrical insulation, mechanical strength, and fire resistance.

Purpose of Reinforcement Liners

Reinforcement liners serve multiple functions in tubular busbars:

• Electrical insulation: They prevent short circuits and maintain safe voltage separation between the busbar and surrounding structures.
• Mechanical support: Liners provide structural integrity, reducing deformation under thermal expansion or mechanical stress.
• Fire and environmental protection: Many liners are self-extinguishing and resistant to moisture, dust, and pollution, ensuring reliable operation in harsh environments .

Common Materials

Reinforcement liners are typically made from fiber-reinforced plastics (FRP), including:

• Sheet Molding Compound (SMC) and Dough Molding Compound (DMC), which offer high tensile and flexural strength .
• Thermoplastics and polymers such as Nomex®, Tedlar®, Mylar®, Kapton®, Ultem®, and epoxy-glass composites, which provide excellent dielectric properties and thermal stability .
• Heat-shrink tubing or epoxy powder coatings may also be applied for additional insulation and protection .

Design Considerations

When selecting or designing a reinforcement liner for tubular busbars, engineers consider:

• Busbar dimensions and current rating, which influence liner thickness and material choice.
• Electrical characteristics, including dielectric strength, tracking resistance, and impedance.
• Mechanical requirements, such as compressive and impact strength to withstand installation and operational stresses .
• Standards compliance, including UL 94 V0 fire rating and DIN EN 61439-1 for busbar supports .

Application

Reinforcement liners are installed inside or around tubular busbars in substations, switchgear, and distribution panels. They are often combined with busbar supports and clamps to ensure secure mounting and alignment while maintaining electrical safety . Custom liners can be fabricated to fit specific busbar geometries and voltage levels, including 33kV, 66kV, and 132kV systems . In summary, reinforcement liners are critical components that enhance the safety, durability, and performance of tubular busbars, combining insulation, mechanical reinforcement, and environmental protection in one solution.