High Voltage Transformer Bushing
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EN 24KV250 Transformer Bushing Type 3
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Standard: EN 50180 / EN 60137 (European norms for HV bushings)
Rated Voltage: 24 kV (system voltage)
Type Designation: Type 3
Current Rating: 250 A (continuous)
Basic Insulation Level (BIL): 125 kV
Material Options:
Outdoor: Porcelain
Internal Insulation: Oil-paper
Creepage Distance: ≥450 mm
Mounting: Flange or through-type (depends on transformer design)
Primary Applications
Oil-immersed distribution transformers (20/24 kV class)
Pad-mounted or substation transformers
Renewable energy systems (wind/solar farm step-up transformers)
Industrial power units (mining, steel plants)
Outdoor installations (weatherproof design)
Standards Compliance:EN 50386
Usage & Applications:
Primary Role:
Provides electrical insulation and mechanical support for conductors passing through a transformer tank.
Common Installations:
Power transformers (distribution/substation levels).
Switchgear, reactors, or capacitor banks.
Suitable for oil-immersed or dry-type transformers.
Key Functions:
Prevents short circuits between live conductors and grounded parts.
Seals transformer oil/gas (if applicable).
Withstands environmental stress (pollution, moisture, UV).
Variants & Alternatives:
Oil-impregnated paper bushings (for oil-filled transformers).
Dry-type or epoxy resin bushings (for maintenance-free applications).
SF₆-insulated bushings (for gas-insulated systems).
General Description
Application
Used primarily for outdoor installation on distribution transformers within 20 kV electrical systems in regions following EN standards. It's specifically chosen when the transformer design requires the larger Type 3 mounting interface.
Material
Commonly made from high-quality electrical porcelain (usually brown or grey glazed) or composite materials (like silicone rubber sheds over a fiberglass core).
Function
It reliably insulates the live conductor from the grounded tank, provides a sealed passage for the conductor, offers mechanical support, and serves as the external connection point. The Type 3 classification ensures it fits transformer tanks prepared with the corresponding larger mounting arrangement.
Creepage Distance
This parameter (e.g., 525 mm, 600 mm, 720 mm, etc.) must be selected based on the expected environmental pollution level where the bushing will be installed, following guidelines in EN/IEC standards.