Composite or Porcelain Hollow Insulator: Selection Checks
Compare pressure, cantilever load, weight, creepage, flange interface and the model-specific tests under IEC 61462 or IEC 62155.
Selection note: use this guide to compare technical requirements. Confirm catalog ranges, typical values and standard clauses against the model, edition and agreed test conditions; project acceptance follows the approved drawings and technical agreement.
On this page
- 01How do IEC 61462 composite and IEC 62155 porcelain hollow insulators differ in structure?
- 02How are pressurized hollow insulators tested for SF6 containment and mechanical safety?
- 03Why do composite hollow insulators outperform porcelain in high seismic zones?
- 04How should gas-tight flange sealing be checked over the service life?
- 05Frequently asked questions
- 06Standards & sources
In short
Compare composite and porcelain hollow insulators by the specified dimensions, materials, pressure and tests; use IEC 61462 and IEC 62155 for their respective product types.
- Composite hollow insulators (CHI) combine a multi-axis filament-wound FRP load-bearing tube with an HTV/LSR silicone housing; porcelain hollow insulators (PHI) use a vitrified C-130 aluminous ceramic body.
- Composite and porcelain hollow units can fail differently under internal arc or overpressure; compare the complete assembly failure test and protection design.
- Composite units may reduce assembly mass; compare actual weights and seismic loads for the specified designs.
- For pressurized SF6 applications, agree the leak-test method and project acceptance limit.
- Use IEC 61462 for a composite hollow unit and IEC 62155 for a porcelain hollow unit; compare the proposed design and test reports.
Choose between composite and porcelain by checking pressure, cantilever load, mass, creepage and flange drawings for the actual unit.
01How do IEC 61462 composite and IEC 62155 porcelain hollow insulators differ in structure?
A porcelain hollow insulator (IEC 62155) is a single-piece C-130 aluminous ceramic cylinder with extruded ribs, vitrified at about 1300 degrees C and cemented into cast iron or aluminum flanges. A composite hollow insulator (IEC 61462) separates mechanical and environmental duties: an epoxy-impregnated E-glass filament-wound tube carries internal pressure and cantilever loads, while a molecularly bonded HTV or LSR silicone rubber sheath provides hydrophobicity and creepage.
Compare the load-bearing tube or ceramic body, housing and flange joint separately; request the assembly drawing and material schedule.
02How are pressurized hollow insulators tested for SF6 containment and mechanical safety?
For a pressurized hollow insulator, specify the operating and test pressures, complete assembly geometry and agreed pressure, leakage and failure tests. FRP and porcelain bodies have different fracture behaviour, but neither material alone guarantees a fragment-free result; review the tested assembly and surrounding protection.
Specify maximum service pressure, pressure-test method, leakage limit and the assembly failure criteria before comparing designs.
- Maximum Service Pressure (MSP): specified by the switchgear OEM, typically 0.40 MPa to 0.70 MPa gauge for SF6 or eco-gas mixtures.
- SF6 decomposition resistance: inner FRP bore is formulated with cycloaliphatic epoxy or protective liner to resist HF and SO2 byproducts.
| Engineering Parameter | Composite hollow insulator | Porcelain hollow insulator |
|---|---|---|
| Governing IEC Standard | IEC 61462 / GB/T 21429 | IEC 62155 / IEC 60168 / GB/T 8287.1 |
| Voltage Coverage | 11 kV to 800 kV (up to 1200 kV UHV HCI) | 11 kV to 1100 kV AC/DC |
| Structural Body & Housing | Filament-wound E-glass FRP + HTV/LSR silicone | Vitrified C-130 aluminous electrical porcelain |
| Relative Mass | Compare actual design mass | Compare actual design mass |
| Cantilever Breaking Load | 10 kN to 60 kN (custom fiber layup) | High stiffness, limited by brittle tensile limit |
| Overpressure Failure Mode | Review assembly failure test and fragments | Review brittle-fracture protection |
| Gas Tightness Verification | Helium leak test to agreed limit | Hydraulic / pneumatic pressure test |
| Project references | Request supplier- and model-specific references | Request supplier- and model-specific references |
03Why do composite hollow insulators outperform porcelain in high seismic zones?
Composite construction can reduce mass and change failure behaviour, but seismic suitability depends on the actual cantilever rating, flange and support structure.
Compare model-specific mass and cantilever results together with the equipment support and seismic calculation; material choice alone does not establish seismic performance.
“Buyer check: compare actual mass, pressure and cantilever ratings, creepage and flange geometry by model.”
04How should gas-tight flange sealing be checked over the service life?
During service, review flange-seal condition and gas-loss records against the agreed maintenance and leak-test plan.
Furthermore, the external silicone rubber sheath is extended over the triple-junction point (where metal flange, FRP tube and outside air meet) and sealed with a weather-resistant silicone bead. This prevents moisture ingress into the mechanical joint during 1000-hour salt-fog and thermal-mechanical load cycling tests under IEC 61462.
Applicable EONOVA Equipment
Conclusion
Request the proposed unit drawings and pressure, cantilever and leak-test evidence before choosing a composite or porcelain hollow insulator.
Talk to an EONOVA engineerFrequently Asked Questions
When should a switchgear OEM choose HTV vs LSR silicone rubber on a composite hollow insulator?
+
HTV and LSR are different processing routes for a silicone housing. Select by the proposed shed geometry, bond process and the model-specific material and interface test evidence.
What inputs are needed to quote a custom composite or porcelain hollow insulator?
+
Please provide the 2D/3D assembly drawing showing overall height, inner bore diameter, top and bottom flange bolt circle (PCD), O-ring groove geometry, rated system voltage, required creepage distance, maximum service gas pressure (MSP) and cantilever breaking load (SML/MML).
Can the quoted supplier supply drop-in composite replacements for broken porcelain hollow insulators?
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Do not assume drop-in fit. Compare the old and proposed drawings for bore, overall height, flange bolt circle, sealing groove, pressure and cantilever duty, then approve a replacement drawing.
Standards & Sources
- [1]IEC 61462: Composite hollow insulators: Pressurized and unpressurized insulators for use in electrical equipment with rated voltage greater than 1000 V
International Electrotechnical Commission (TC 36)
Supports: Design, pressure rating, thermal-mechanical load testing and routine testing of composite hollow insulators.
- [2]IEC 62155: Hollow pressurized and unpressurized ceramic and glass insulators for use in electrical equipment with rated voltages greater than 1000 V
International Electrotechnical Commission (TC 36)
Supports: Dimensional, flexural strength and pressure withstand requirements for porcelain hollow insulators.
- [3]IEC 60672-3: Ceramic and glass insulating materials: Specifications for individual materials
International Electrotechnical Commission (TC 15)
Supports: Material classification and mechanical properties of C-130 high-strength aluminous porcelain.
- [4]CIGRE TB 506: Application of Composite Insulators to Switching Equipment
CIGRE Working Group A3.21
Supports: Application experience and mechanical safety considerations for composite switchgear insulators.
Selection guidance for buyers. Confirm specifications and test evidence for the quoted model and supplying entity.
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