220kV Composite Insulation Termination

CHARACTERISTICS

I. Basic Definitions and Applicable Standards

1. Voltage Level Correspondence

220kV: Domestic standard, phase voltage 64kV, maximum system operating voltage Um=230kV. Compatible with single-core XLPE high-voltage cables, cross-section 95～2500mm², models YJZWFY4 (oil-immersed composite outdoor terminal) and dry-type plug-in composite terminal.

II. Structural Composition and Material Characteristics
The core of the composite terminal consists of five parts: composite bushing, prefabricated stress cone, internal insulation medium, sealing structure, and hardware grounding system:

1. Internal Insulation Filling Medium

Oil-immersed type: Polyisobutylene insulating oil, insulation, heat dissipation, and buffering; optional pressure relief and oil level monitoring;

Dry-type plug-in type: Epoxy prefabricated solid insulation, oil-free and leak-proof, maintenance-free, GIS-specific.

2. Multi-layer Sealing System
Upper and lower flanges + tail pipe triple silicone rubber seal, resistant to high and low temperatures, waterproof, moisture-proof, and salt spray penetration-proof; flange rounded transition to prevent surface discharge.

3. Conductive and Grounding Fittings: Aluminum alloy equalizing cover, copper crimped terminal blocks, stainless steel fasteners; spring-loaded grounding ring for reliable discharge of induced charge and fault short-circuit current.

III. Electrical Performance Characteristics (Core Insulation Withstand Voltage Indicators)

Key Electrical Advantages: Silicone rubber bushings are highly hydrophobic, preventing the formation of a continuous water film in humid or polluted environments; flashover voltage is significantly higher than that of porcelain bushings; optimized creepage distances for both large and small bushings meet Class IV heavy pollution and coastal salt spray conditions.

IV. Mechanical Properties

1. Bending Strength: Minimum bending moment ≥2400 N·m, capable of withstanding conductor tension, strong winds, and seismic loads;

2. Pressure Resistance and Explosion-Proof: Internal pressure withstands 1.6 MPa, breaking pressure ≥2.0 MPa; fault internal pressure increases result in only slight deformation, with no shattering fragments;

3. Lightweight: Significantly reduced bushing weight for the same voltage, lower cost of supports and civil engineering foundations, and easier hoisting.

V. Additional Features of Dry-Type Composite Terminals (GIS Plug-in Type)

1. Completely dry and oil-free, completely eliminating the risk of oil leakage and fire;

2. Factory-prefabricated epoxy insulation components, requiring only plug-in connection on-site, resulting in extremely fast installation;

3. Can be pre-installed in separate parts, with matching conduits pre-installed at the GIS factory, requiring only cable connection on-site, reducing on-site testing;

4. No aging issues with the filling medium, resulting in stronger long-term insulation stability.