Silicone Rubber Composite Substaion Insulator
Composite substation post insulators (also called composite post insulators) are composite insulating components used in substations to support high-voltage busbars/equipment and provide electrical insulation. They replace traditional porcelain posts and are widely used in 10kV and above substations.
I. Core Structure (Three-Layer Integrated)
* Core Rod (Inner Insulation + Main Load Bearing): Fiberglass epoxy resin pultruded rod, solid cylinder, with tensile/bending strength far exceeding that of steel, providing mechanical support and internal insulation.
* Umbrella Sheath (Outer Insulation + Protection): Silicone rubber (mainstream) or EPDM rubber, one-piece molded skirt, increasing creepage distance, preventing flashover, resisting aging, and possessing strong hydrophobicity.
* End Fittings: Upper and lower metal flanges/joints, hot-dip galvanized for corrosion protection, reliably connected to the core rod, used for fixing to the frame/equipment.
II. Main Applications (Substation Specific)
* Supports high-voltage busbars, disconnecting switches, circuit breakers, instrument transformers, etc.
* Withstands mechanical loads such as bending, compression, torsion, and tension.
Achieve electrical isolation between live conductors and the grounding structure.
III. Key Advantages (Comparison with Porcelain Posts)
Lightweight: Only 1/5–1/10 the weight of comparable porcelain posts, making installation and transportation easier.
Strong Anti-pollution Flashover: Silicone rubber has good hydrophobicity, and its pollution withstand voltage is 30%–50% higher than porcelain, making it suitable for heavily polluted areas.
Impact/Shock Resistance: Not easily broken, its shock resistance is superior to porcelain.
Cleaning-Free and Low-Maintenance: Good self-cleaning properties, making long-term operation more worry-free.
Compact Size: Shorter length for the same insulation level, saving substation space.
Our factory & quipment
Customized Size Available
The Drawing
500kV Transmission Line
500kV power lines form the backbone of the ultra-high voltage AC transmission network. Their core function is for large-capacity, long-distance power transmission across provinces and regions, serving as a crucial channel connecting large power sources and load centers, and enabling grid interconnection.
I. Core Positioning and Advantages
Voltage Level: AC 500kV (belonging to EHV, 330–765kV range)
Main Applications
Inter-provincial/inter-regional power transmission (e.g., West-to-East Power Transmission)
Provincial power grid backbone, large power plant transmission
Regional power grid interconnection, hub substation connection
Core Advantages
Large Capacity: Single-circuit natural power approximately 850–950MW, with a maximum of 2000–3000MW
Low Loss: At the same power, the current is approximately 1/2.27 of 220kV, significantly reducing losses
Provincial Corridor: The transmission capacity per unit corridor is 4–5 times that of 220kV, saving land resources
Strong Stability: Supports the safe and stable operation of large power grids, reducing short-circuit current levels.
II. Typical Technical Parameters (Domestic Mainstream)
1. Electrical Parameters
Rated Voltage: 500kV (maximum operating voltage 550kV)
Number of Phases/Frequency: Three-phase, 50Hz
Conductor Configuration: 4 Mainly split type (4×400, 4×630, 4×720mm²), large capacity uses 6-split type
Surge impedance: approx. 270–290Ω
Saturated power transmission (SIL): approx. 860–920MW
Limited transmission capacity: approx. 2000–3000MW per circuit (depending on system conditions)
Insulators: disc suspension type, 25–30 discs/string (300kN class)
Safe distance: minimum 14m from ground (residential area), 7.5m from building
2. Mechanical and Environmental Specifications
Towers: Goblet-shaped, cat-head-shaped, drum-shaped, etc., height 30–60m
Span: 400–800m on flat ground, large spans up to 1000–1500m
Permissible conductor temperature: Steel-cored aluminum stranded wire 90℃, heat-resistant type 150℃
Environmental control: Strict control of corona, audible noise, and radio interference
III. Main Components
Conductors: Multi-split steel-cored aluminum stranded wire (JL/G1A), reducing corona and reactance
Towers: Steel structure/concrete, supporting conductors and ground wires
Insulators: Disc-type or composite insulators, providing electrical insulation
Hardware: Various connectors connecting conductors, insulators, and towers
Ground wires: Two, for lightning protection and also serving as communication channels
Foundations: Base of the tower, bearing vertical and horizontal loads
Auxiliary facilities: Surge arresters, vibration dampers, spacers, grounding devices, online monitoring
IV. Typical Application Scenarios
West-to-East Power Transmission: e.g., Tianshengqiao-Guangdong, Three Gorges- Inter-regional transmission channels including Shanghai
Large-scale power transmission: Centralized transmission of hydropower, thermal power, nuclear power, and wind power from bases
Regional main grid: 500kV ring network/chain structure in each province to ensure power supply reliability
Grid interconnection: Enables inter-provincial/inter-regional power exchange and emergency support
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