NLL Aluminum Alloy Strain Clamp Bolt Type
Product Overview
The NLL Aluminum Alloy Strain Clamp Bolt Type is a specialized strain clamp designed for fixing and tensioning of ACSR, AABC, and stranded aluminum conductors on distribution lines. Widely recognized in the industry under alternative names including bolt-type strain clamp, dead-end grip, tension clamp, this product serves as a critical component in 10 kV and below overhead lines systems. Note: When used on overhead insulated conductors, strip the insulation layer before use.
Advantages
- “Bolt-type compression design” — uniform clamping pressure distributes stress evenly across the conductor, preventing deformation
- “Non-magnetic aluminum body” — cast aluminum alloy eliminates hysteresis and eddy current losses under power frequency
- “Corrosion-resistant finish” — all exposed steel hardware is hot-dip galvanized for long outdoor service life
- “Wide conductor compatibility” — multiple models cover conductor cross-sections from 16 mm² to 400 mm²
- “Easy field installation” — wrench-tightened bolt mechanism requires no special tools or compression equipment
Technical Parameters
| Model | Applicable Conductor Diameter (Including Wrapping) (mm) | Main Dimensions (mm) | U-Bolt | Nominal Failure Load (kN) | ||
|---|---|---|---|---|---|---|
| C | M | M | Qty | |||
| NLL-1 | 8.0~12.0 | 18 | 16 | 12 | 2 | 40 |
| NLL-2 | 11.0~16.0 | 18 | 16 | 12 | 2 | 40 |
| NLL-2 (Reinforced) | 11.0~16.0 | 18 | 16 | 12 | 2 | 60 |
| NLL-3 | 15.0~20.0 | 27 | 16 | 14 | 3 | 70 |
| NLL-4 | 19.0~24.0 | 30 | 18 | 14 | 3 | 90 |
| NLL-5 | 23.0~29.0 | 36 | 22 | 16 | 4 | 120 |
| NLL-6 | 25.9~32.7 | 42 | 22 | 18 | 4 | 120 |
Note: Dimensions may vary slightly based on manufacturing tolerances. Contact our engineering team for custom sizes or special requirements.
Material & Manufacturing
- Material: high-strength cast aluminum alloy
- Secondary components: hot-dip galvanized steel bolts and hardware
- Surface treatment: Hot-dip galvanizing in accordance with ISO 1461 / ASTM A153 / IEC 61589, minimum zinc coating thickness 65 μm
- Manufacturing process: Precision forging, casting, or CNC machining of critical dimensions, followed by full galvanizing immersion. Dimensional accuracy controlled within ±0.5 mm tolerance on mounting interfaces
- Quality assurance: Every batch undergoes dimensional inspection, galvanizing thickness testing (magnetic or gravimetric method per ISO 2178), and visual surface examination. Mill test certificates (MTC) available upon request
Application Scope
- Fixing and tensioning of acsr, aabc, and stranded aluminum conductors on distribution lines
- 10 kV and below distribution lines for ACSR, AABC, and aluminum stranded conductors
- Overhead line terminal and tension tower dead-end connections
- Pole-top and crossarm conductor termination points
Frequently Asked Questions
Q: What is the difference between NLL and NXLH? A: NLL is standard bolt-type strain clamp for ACSR/ABC conductors. NXLH series is designed specifically for aluminum-clad steel conductors with enhanced mechanical grip.
Q: Can NLL clamps be reused? A: NLL clamps can be reused if the bolt and conductor groove are undamaged. Inspect for groove deformation or corrosion before reinstallation.
Q: What torque should be applied to the bolts? A: Refer to the manufacturer torque specification (typically 25-45 N·m depending on model). Over-tightening may deform the conductor.
Industry Standards & Compliance
| Standard | Scope |
|---|---|
| IEC 61589 | Galvanizing requirements for overhead line hardware |
| ISO 1461 | Hot-dip galvanized coatings on iron and steel articles |
| ASTM A153 | Zinc coating (hot-dip) on iron and steel hardware |
| GB/T 2314 | General requirements for overhead line fittings |
| GB/T 2317 | Mechanical testing methods for overhead line hardware |
| DL/T 765.2 | Suspension and strain hardware for overhead power lines |