FRP Core
E-glass or ECR glass fiber pultruded with epoxy resin. The core carries tensile and bending loads. ECR glass can be specified where electrical corrosion resistance is a priority.
Custom Silicone Composite Insulators
Fecision manufactures composite insulators with an HTV silicone rubber housing, a load-bearing FRP core, and crimped galvanized steel end fittings for outdoor power systems.
- One-piece silicone housing and shed molding
- FRP core and crimped fittings for mechanical load transfer
- Profiles developed around voltage, creepage, load, and pollution requirements
Polymer Insulator Basics
What Is a Silicone Composite Insulator?
A silicone composite insulator is an electrical insulator built from three bonded parts: a fiberglass-reinforced plastic (FRP) core that carries the mechanical load, a silicone rubber housing with sheds that protects the core and provides creepage distance, and metal end fittings that connect the insulator to the line hardware.
Also called polymer insulators or composite line insulators, they support the conductor and keep current on the line like porcelain or glass insulators. Their non-brittle construction, hydrophobic surface, and low weight are especially useful where pollution, coastal exposure, difficult access, or installation handling affect the project.
Suspension, tension, line post, station post, and railway catenary formats can be reviewed against the specified voltage class, mechanical load, and installation geometry.
Silicone Composite Insulator Structures
Interface quality is central to long-term reliability. Moisture entering between the silicone housing and FRP core can damage the interface and increase brittle-fracture risk, so bonding and sealing are treated as part of the primary design.
Housing and Sheds
HTV silicone rubber injection molded directly onto the primed core. The housing protects against weather, UV, and pollution while establishing the required creepage path.
End Fittings
Ductile iron or forged steel with hot-dip galvanizing. Hydraulically crimped fittings connect to line hardware and transfer mechanical load into the FRP rod.
Sealing System
RTV silicone sealant with an elastomeric sealing element at the fitting mouth. This interface forms the moisture barrier at each end of the housing.
Materials We Use in Composite Insulators
Material selection is tied to electrical, mechanical, environmental, and project-documentation requirements. Material certificates for the silicone compound, rod, and metal components can be included when specified in the order.
| Material | Typical Specification | Why It Is Selected |
|---|---|---|
| Silicone Rubber | HTV polydimethylsiloxane with ATH filler and fumed-silica reinforcement | Hydrophobic surface behavior; ATH supports tracking and erosion resistance. |
| FRP Rod | E-glass fiber and epoxy, with ECR glass available by project requirement | High tensile strength at low weight; ECR grades support applications with elevated brittle-fracture risk. |
| End Fittings | Ductile iron or forged steel, hot-dip galvanized to the specified coating standard | Transfers mechanical load and provides corrosion-resistant connection points. |
| Sealing System | RTV silicone sealant with a project-specified elastomeric sealing element | Maintains a flexible moisture barrier through outdoor exposure and thermal cycling. |
How Silicone Composite Insulators Are Made？
The process is simple to describe but sensitive to execution. Rod preparation, controlled priming, one-piece molding, crimping, and end sealing determine whether the interfaces remain stable in service.
- PrepareRod and Fitting PreparationFRP rods are cut to length, rod ends and metal fittings are prepared, and incoming surfaces are inspected.
- BondCleaning and PrimingThe rod is cleaned and coated with a compatible primer inside a controlled process window to establish reliable bonding.
- MoldHousing Injection and VulcanizationHTV silicone is injected around the primed rod under heat and pressure, curing the housing and sheds as one bonded body.
- InspectFinishing and Visual InspectionFlash is trimmed before checking the housing for bubbles, inclusions, thin areas, surface defects, and shed damage.
- AssembleCrimping and End SealingMetal fittings are hydraulically crimped to the approved parameters, then each fitting mouth is sealed against moisture entry.
- ReleaseMarking, Routine Tests and PackingIdentification and traceability are applied, agreed routine inspections are completed, and released units are protected for shipment.
Advantages of Silicone Composite Insulators
Composite construction separates the mechanical core from the external insulation surface, creating practical advantages for transport, installation, polluted environments, and custom line design.
Lower Weight
A composite unit can weigh substantially less than an equivalent porcelain string, reducing tower load, transport effort, and handling requirements.
Hydrophobic Surface
Silicone repels water and can transfer hydrophobic behavior to surface contamination, limiting formation of a continuous conductive water film.
Non-Brittle Construction
The polymer housing does not shatter like porcelain or glass, reducing impact-related breakage during transport, installation, and service.
Reduced Cleaning Demand
In suitable pollution classes, hydrophobic silicone can reduce reliance on routine washing. Maintenance planning still follows the utility's environment and inspection policy.
Profile Design Freedom
Shed diameter, spacing, profile, and overall length can be developed around creepage, voltage, pollution, and dimensional requirements without ceramic kiln constraints.
Composite Insulator Applications
Configuration and material details are selected around the system voltage, installation load, pollution severity, altitude, corrosion exposure, and project standard.
Overhead Transmission Lines
Suspension and tension insulators for overhead line structures at the project's specified voltage and mechanical rating.
Distribution Networks
Dead-end, line post, and pin-type formats for urban and rural feeder systems.
Substations
Station post and application-specific composite insulation for switchgear, bus support, and transformer assemblies.
Railway Catenary
Composite insulators developed for overhead contact systems and railway electrification hardware.
Wind and Solar Farms
Lightweight outdoor insulation for remote terrain and coastal renewable-energy installations.
Heavy Pollution Environments
Housing profiles for coastal salt fog, cement dust, petrochemical zones, and other high-contamination service conditions.
How We Check Every Silicone Insulator
A complete quality plan distinguishes tests that qualify a design family from routine checks applied to production units. The exact plan is agreed against the insulator type, customer specification, and applicable standard.
Type and Material Tests
Depending on the product type and market, the qualification plan may reference IEC 61109, IEC 60587, IEC 61952, or applicable ANSI C29 requirements.
- Electrical withstand, impulse, tracking, erosion, and pollution-aging tests as specified
- Mechanical design-load and fitting-interface verification
- FRP core water-diffusion and material-characterization tests
- Third-party witnessing or laboratory testing when required by the project
Routine and Batch Inspection
- Dimensions, creepage distance, shed profile, marking, and appearance
- Specified mechanical proof-load testing and batch sampling
- Hydrophobicity classification and silicone housing inspection
- Galvanizing-thickness and end-fitting assembly checks
- Interface-integrity checks using the approved sampling method
- Routine electrical testing when included in the control plan
Get a Quote for Your Silicone Composite Insulators
Send the voltage class and project drawing for an engineering review.