ANSI 1.2kV 250A Transformer Bushing

High Current Low Voltage Porcelain Bushing | 30kV Lightning Impulse Withstand | ANSI C76

Rated Voltage: 1.2 kV | Rated Current: 250 A | Creepage Distance: ≥25 mm | BIL: 30 kV

This ANSI standard low voltage transformer bushing is designed for the LV side of larger distribution transformers, pad-mounted transformers, and substation auxiliary transformers requiring higher current capacity. Rated at 1.2kV and 250A continuous current, it shares the same high insulation withstand characteristics as the 125A version: lightning impulse withstand of 30kV and dry power-frequency withstand of 10kV. The robust porcelain insulator and flange mount design ensure oil-tight installation, UV resistance, and long service life. Direct OEM replacement for standard 1.2kV 250A bushings.

Designed for compatibility and durability, this bushing is ideal for a wide range of transformers used in commercial buildings, industrial plants, and power distribution units. Its standard design facilitates easy installation and replacement, minimizing downtime.

As a professional manufacturer of porcelain insulator and porcelain bushing, we offer good quality and low price porcelain bushing for transformer and capacitor and switch.

Technical Specifications

Electrical Withstand Capability – Engineering Summary

Key Engineering Features

• ANSI C76 / IEEE C57.19.01 compliant – Full compliance for North American utility and industrial applications

• 250A continuous current – Suitable for larger LV windings and higher kVA transformers

• 30kV BIL – Standard impulse withstand for 1.2kV class exposed bushings (per ANSI C57.12.00)

• ≥25mm creepage distance – Meets minimum requirements for normal pollution environments

• 10kV dry withstand – Verified insulation strength under clean, dry conditions

• Wet-process porcelain – Non-porous, high tracking resistance, excellent outdoor durability

• Heavy-duty terminal – Pad connector standard (2-hole NEMA pattern) for secure high-current connection

• Flange mount with gasket groove – Oil-tight seal on transformer tank cover or wall

• -40°C to +55°C operation – Reliable performance across extreme temperature ranges

Dimensional Data (Typical – Confirm with Datasheet)

Note: The 250A bushing typically has a slightly larger flange and terminal pad than the 125A version. For certified dimensional drawings, request the product datasheet.

Features & Benefits:

• ANSI Standard Compliance: Guarantees interoperability, reliability, and adherence to recognized industry specifications for consistent performance.

• Optimized for 1.2KV / 250A: Precisely engineered for medium-voltage, mid-current applications, providing a perfect balance of safety and efficiency.

• High-Grade Porcelain Construction: Offers excellent dielectric properties, high mechanical strength, and outstanding resistance to environmental factors like moisture and pollution.

• Proven Durability: The ceramic material ensures thermal stability and a long service life with minimal maintenance requirements.

• Versatile Application: Suitable for power transformers, distribution transformers, and other electrical equipment requiring a reliable medium-voltage bushing solution.

Compliance & Testing

Each 1.2kV 250A transformer bushing is factory tested per ANSI C76. A Factory Acceptance Test Report (FAT) is included with each shipment, covering:

• Visual and mechanical inspection

• Dimensional verification (critical mounting and sealing dimensions)

• Power-frequency dry withstand test (10kV, 1 minute)

• Lightning impulse withstand test (30kV, 1.2/50μs, 3 positive and 3 negative impulses)

• Flange seal leak test (50kPa air pressure, 1 minute)

• Porcelain surface integrity check (dye penetrant on sample basis)

• Terminal connection resistance measurement (for pad connector version)

Third-party witness testing: SGS, TÜV, Bureau Veritas, or Intertek – available upon request.

Ordering Information

To place an order or request a quote, please specify:

Typical lead time: 15–30 days depending on quantity (stock units may be available)

Typical Applications

• Low voltage side of larger distribution transformers (500kVA – 2500kVA range, 1.2kV LV)

• Pad-mounted transformers requiring 250A LV termination

• Substation station service transformers with higher auxiliary loads

• Industrial control transformers (1.2kV primary or secondary)

• Transformer repair and maintenance – direct OEM replacement for 250A LV bushings

• Re-bushing projects upgrading from 125A to 250A (check flange compatibility)

Cross-Reference Information

This bushing is dimensionally compatible with standard 1.2kV 250A bushings originally supplied on:

• ABB / Cooper (formerly McGraw-Edison)

• ERMCO (larger pad-mounted units)

• Eaton (Cooper Power series – 250A LV)

• Siemens (medium distribution transformers)

• Delta Star

• Virginia Transformer (250A LV termination)

For cross-reference verification, please provide the OEM part number or a sample drawing.

Comparison Table – 125A vs 250A Models

Parameter	125A Model	250A Model
Rated Voltage	1.2 kV	1.2 kV
Rated Current	125 A	250 A
Creepage Distance	≥25 mm	≥25 mm
Lightning Impulse Withstand	30 kV	30 kV
Power-Frequency Dry Withstand	10 kV	10 kV
Typical Flange Diameter	75–85 mm	85–95 mm
Standard Terminal	Plain stud (M10 / 3/8″)	Pad connector (2-hole)
Typical Application	Smaller transformers (≤500kVA)	Larger transformers (500–2500kVA)

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