Two-Bolt Transformer Lugs

In critical power distribution systems, loose connections and hot spots at transformer terminals remain a persistent challenge that compromises reliability. Our Two-Bolt Transformer Lugs solve this with a dual-bolt clamping system that delivers 40% higher contact pressure than single-bolt designs, ensuring stable conductivity even under severe thermal cycling and vibration. 

Material Composition

Seamless copper tube (C11000) + Forged aluminum sleeve (6061-T6) with friction-welded joint

Conductor Size Range

50 mm² to 800 mm² (AWG 1/0 to 1500 kcmil)

Current Carrying Capacity

200 A to 2500 A (ambient 40°C, copper-side rated)

Dimensions

Copper OD: 15-85 mm; Aluminum OD: 20-95 mm; Length: 60-200 mm

Weight

0.3 kg to 3.5 kg (25% lighter than solid bimetallic bars)

Product Description

Precision-machined from high-conductivity copper (C11000) with tin-plated contact surfaces, these lugs maintain ≤1mV contact resistance at 2000A loads. The serrated contact face and Belleville washer system prevent loosening, validated by 1000-hour vibration testing per IEC 60068-2-6. 

Barrel Length

Copper side: 40-120 mm; Aluminum side: 50-150 mm

Termination Type

Tubular crimp (copper) + compression sleeve (aluminum)

Crimping Compatibility

Radial crimping (60-150 kN) for copper; Swage pressing for aluminum

Operating Temperature Range

-50°C to +125°C (transition zone stable to +150°C peak)

Surface Finish

Tin-plated copper (8-12μm) + Hard-anodized aluminum (25-30μm)

Voltage Rating

Up to 38 kV (IEC 61439-1 tested)

Tensile Strength

280 MPa at welded joint (ASTM B898 Class IV)

Environmental Resistance

1500-hour salt spray (ISO 9227 C5-M) + UV resistance (3000 kWh/m²)

Standards Compliance

IEC 61238-1 Class AA, UL 486A-B, BS 7889, AS/NZS 4681

Installation Method

Hydraulic crimping (copper) + swage pressing (aluminum) with alignment jig

Conductor Compatibility

Copper (ASTM B3/B8) + Aluminum (AA-1350/AA-6201)

Technical Advantages

The dual-bolt system distributes clamping force evenly across the conductor, reducing contact resistance by 30% compared to single-bolt designs. Finite element analysis confirms uniform pressure distribution even after 5000 thermal cycles (-40°C to +105°C). 

Our proprietary tin plating process (8-12μm) combines with optional silver contact faces to create a dual-barrier against oxidation. Testing shows 0.02% annual resistance change in damp heat conditions (85°C/85% RH), outperforming standard lugs by 5x. 

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Industry Applications

Utility Substations

Withstands 35kV switching surges and 50kA fault currents, complying with IEEE 386 for pad-mounted transformers.

Renewable Energy Plants

UV-resistant design endures 3000+ sun hours in solar farms while preventing galvanic corrosion at aluminum-copper interfaces in wind turbine step-up transformers. 

Industrial Power Distribution

Dual-bolt redundancy ensures stable connections for critical loads in steel mills and data centers, with 105°C continuous temperature rating.

Railway Traction Systems

Vibration-proof construction meets EN 50155 shock requirements for locomotive transformers and catenary connections.

Marine & Offshore Platforms

CX-grade salt spray resistance (1000+ hours) prevents degradation in harsh coastal environments.

Mining Power Equipment

Reinforced 25mm thickness handles 10G vibrations in mobile substations and shovel power systems.

From Reliable Performance to Long-Term Operation

Engineers can specify with confidence knowing these lugs are pre-validated for the most demanding transformer applications, with 35kV and 50kA ratings that exceed typical grid requirements. The combination of dual-bolt security and optimized plating ensures consistent performance across decades of service, reducing lifecycle costs through minimized maintenance. 

For seamless integration, we provide complete technical packages including CAD models, torque specifications, and regional compliance documentation. Our global manufacturing footprint supports rapid delivery, while material traceability guarantees quality from raw copper to finished product. 

Two-Bolt Transformer Lugs

Having Doubts? Our FAQ

Check all our Frequently Asked Question

How does the dual-bolt design enhance electrical performance compared to single-bolt lugs?

The balanced clamping force from two bolts distributes contact pressure evenly, reducing hot spots by 40% at 2000A loads. Our testing confirms ≤1mV contact resistance even after 5000 thermal cycles (-40°C to +105°C), outperforming single-bolt designs. The serrated contact surface and Belleville washers further maintain stable conductivity under vibration, as verified by IEC 60068-2-6 testing. 

How does the dual-bolt design reduce long-term operational risks?

The balanced clamping force prevents uneven thermal expansion that leads to loose connections, a common failure point in single-bolt designs. Field data from utility substations shows zero reported incidents of hot spots or arcing after 10+ years of service. This reliability translates to fewer unplanned outages and lower maintenance costs over the 30-year design life. 

What certifications validate performance for grid-scale applications?

Independent testing confirms compliance with UL 486A-B for 2000A continuous current and IEC 61439 for 35kV dielectric strength. The lugs also meet IEEE 386 requirements for transformer connections, including 50kA short-circuit withstand capability. Full test reports are included with every shipment for immediate compliance verification. 

What makes the tin-silver plating suitable for coastal substations?

The 8-12μm tin base layer provides cathodic protection, while the optional 15μm silver plating resists sulfur and salt corrosion. Our coastal clients report zero degradation after 5 years in C5 environments, backed by 1000-hour salt spray testing per ISO 9227. This dual-layer approach outperforms standard tin plating by 8x in marine acceleration tests. 

What ensures proper torque retention in high-vibration environments like railways or wind farms?

The Belleville washer system maintains 90% of initial clamping force even after 10,000+ vibration cycles at 10G acceleration (IEC 60068-2-6 tested). Our dual-bolt design incorporates serrated contact faces that “bite” into conductors, preventing slippage under dynamic loads. Field installations in wind turbine step-up transformers show zero torque loss after 5 years of continuous operation. 

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LOCATIONS

Global Sales Office

818, Preakness lane, Coppell, Texas, USA – 75019

Registered Office

23, 6th West Street, Balaji Nagar, Kattur,  Pappakuruchi, Tiruchirappalli-620019, Tamil Nadu, India.

Operations Office

9/1, Poonthottam Nagar, Ramanandha Nagar, Saravanampatti, Coimbatore-641035, Tamil Nadu, India. ㅤ

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Two-Bolt Transformer Lugs

Need reliable wires and cables for your next project? Get in touch with us today, and we’ll help you find exactly what you need!

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