Selecting the right stringing block is a critical decision that directly impacts the safety and efficiency of your project. As a leading manufacturer, we recommend considering three key factors:

1. Conductor Type & Size: Match the sheave groove and size to the specific conductor or cable you are stringing. Our blocks are designed to accommodate a wide range of ACSR and other conductors.

2. Application: The block type depends on your project. Single sheave blocks are used for single conductors, while three-sheave or five-sheave blocks are specifically designed for stringing bundled conductors.

3. Working Load: The rated load (KN) of the stringing block must exceed the maximum pulling tension anticipated during the stringing operation.

At Ningbo Changshi, we provide a variety of high-quality blocks to meet every project requirement, with options for different materials and configurations.

The material of the sheave is a crucial factor, as it is the point of contact with the conductor. Neoprene-lined aluminum alloy sheaves and high-strength nylon sheaves are preferred for several reasons:

• Conductor Protection: These materials provide a cushioned surface that protects the conductor's outer strands and jacketing from damage, especially during high-tension pulling.

• Reduced Friction: They help to minimize friction, ensuring a smoother stringing process.

• Lightweight Durability: Aluminum alloy and nylon offer a combination of lightweight construction for easy handling with the necessary strength and durability for demanding overhead line projects.

Safety is our top priority. We manufacture our equipment to strict international standards such as ISO 9001 and provide detailed technical specifications. Best practices for safe operation include:

• Pre-Installation Inspection: Always inspect blocks for any damage, wear, or defects before each use. The frame, sheave, bearings, and attachment points should be in perfect condition.

• Correct Bending Radius: Use a block with a sheave diameter that ensures the conductor's bending radius is not compromised during installation, as bending too tightly can damage the cable.

• Working Load Limit (WLL): Never exceed the specified WLL of the block.

• Proper Attachment: Ensure the stringing blocks are securely attached to the pole or tower structure, with fittings that are appropriate for the application.

Conductor stringing blocks are essential for the safe and efficient installation of overhead power lines. The type of block you need depends on the project's specific requirements.

• Single Sheave Blocks: Ideal for pulling a single conductor, guide wire, or OPGW (Optical Ground Wire) on tangent structures.

• Multi-Sheave Blocks: These blocks, with three or five sheaves, are specifically designed for stringing bundled conductors. Bundled conductors are used to increase the capacity of a transmission line and reduce corona losses.

• Universal & Angle Blocks: Universal blocks are versatile and can be used on tangent or light-angle structures. Angle blocks are specially designed for structures where the conductor changes direction.

• Helicopter Stringing Blocks: These are lightweight blocks designed for installation with a helicopter for large-scale or difficult-to-access projects.

At Ningbo Changshi, we offer a full range of blocks for every type of conductor stringing need.

The sheave is the part of the block that comes into direct contact with the conductor. Its material is critical for protecting the conductor and ensuring a smooth pull.

• Aluminum Alloy Sheaves: Known for their lightweight design and high strength, these are the industry standard. We offer them with a neoprene lining to provide extra protection against damage and surface abrasion on the conductor.

• High-Strength Nylon Sheaves: A popular choice for their superior properties in preventing damage to the conductor's surface and reducing friction. They are also non-conductive, which adds a layer of safety during installation.

• Steel Sheaves: While durable, they are generally used in the central part of multi-sheave blocks or in applications where the conductor's surface is not as sensitive.

Safety is paramount in all electrical construction work. To ensure the reliability and longevity of your stringing blocks, follow these best practices:

• Pre-use Inspection: Always perform a thorough inspection before each use. Check for any signs of wear, cracks, or deformation on the frame, sheave, and hook fittings. Ensure the bearings spin freely.

• Proper Sizing: The block's sheave groove must match the conductor diameter precisely to prevent slipping and damage.

• Working Load Limit (WLL): Never exceed the rated WLL of the block. All our products are clearly marked with their WLL to ensure compliance with international safety standards.

• Regular Lubrication: The bearings must be regularly greased to maintain smooth operation and extend the life of the block.

• Proper Storage: Store blocks in a dry, clean environment to prevent corrosion and damage when not in use.

The choice of sheave material is crucial for the safety and integrity of your wire or conductor.

• Nylon Sheaves: High-strength MC nylon sheaves are prized for their non-conductive properties, making them an excellent safety choice, especially when working near live lines. They also offer a low-friction surface, which is gentle on the wire's surface, preventing damage and minimizing wear.

• Aluminum Alloy Sheaves: Aluminum sheaves are a classic industry choice, offering a great combination of strength and lightweight design. Our aluminum sheaves can be lined with neoprene for extra protection, creating a cushioned surface that further reduces friction and prevents abrasion on the conductor during the stringing process.

Selecting the right size is critical to prevent damage to the conductor and ensure efficient stringing. The key factors to consider are:

• Conductor Diameter: The sheave groove of the block must be correctly sized to fit the wire. A groove that is too tight can pinch and damage the conductor, while one that is too loose can cause the wire to jump out of the sheave.

• Working Load: The block's Working Load Limit (WLL) must be greater than the maximum tension the wire will be under during the stringing operation.

• Number of Conductors: For bundled conductor projects, you must use blocks with multiple sheaves (e.g., three or five sheaves) to accommodate all wires simultaneously.

Preventing mechanical damage is a primary concern. It can be achieved by:

• Proper Equipment Selection: Use stringing blocks and rollers with sheaves made from high-strength, low-friction materials like MC nylon or neoprene-lined aluminum, sized correctly for the conductor.

• Controlled Tension: Employ hydraulic tensioners and pullers to maintain a constant, controlled tension throughout the process, preventing the conductor from dragging on the ground or rubbing against objects.

• Pulling Grips: Utilize conductor pulling grips that provide a secure, uniform hold on the cable, distributing the load evenly and avoiding point pressure that can cause damage.

Underground cable laying presents unique challenges, including excessive pulling tension, cable twisting, and mechanical damage from friction. These can be mitigated by:

• Using Lubricants: Applying a high-quality cable lubricant to reduce friction as the cable is pulled through ducts or conduits.

• Cable Rollers: Using strategically placed cable rollers and corner pulleys to guide the cable smoothly around bends and through trenches, preventing kinking or damage.

• Traction Control: Employing a cable pulling winch with precise traction control to prevent over-tensioning, which can stretch or damage the cable's insulation and sheath. Regular inspections of the cable before, during, and after laying are also crucial.

While we do not manufacture nylon braided power cables, we leverage the exceptional properties of a material called MC nylon (cast nylon) in key components of our equipment.

• For Overhead Transmission: Our stringing blocks and rollers often feature MC nylon sheaves. This material is lightweight yet incredibly strong, providing a smooth surface that reduces friction and prevents damage to the expensive conductors during the stringing process. It also offers excellent wear resistance and a longer service life compared to other materials.

• For Underground Cable Laying: We use durable nylon and other synthetic fibers in pulling ropes and accessories because they are lighter and more flexible than steel, offering high tensile strength for pulling cables through conduits and trenches without causing damage.

The primary purpose of a conductor stringing clamp is to provide a secure and non-damaging grip on the conductor during the stringing process. Our clamps, such as our Suspension Clamps, are engineered to support the weight of the conductor and maintain proper tension while preventing abrasion or damage to its surface. Safety is paramount, and our clamps are designed to meet stringent industry standards (e.g., IEEE) for mechanical strength, corrosion resistance, and secure fastening. This ensures the conductor is not compromised, reducing the risk of premature failure and guaranteeing the long-term reliability of the power line.

Conductor damage is a major concern. To prevent issues like conductor sag and abrasion, we advise using a controlled tension stringing method. Our equipment, including our specialized clamps and pullers, is designed to apply tension uniformly, which is crucial for achieving the correct sag profile. We also use durable, polymer-lined grooves in our bullwheels and clamps to prevent scuffing and abrasion on the conductor's surface. Proper installation, following manufacturer-recommended sag-tension charts, and using high-quality clamps are the best measures to protect the conductor and ensure a long service life.

The choice of clamp depends on the specific application and voltage level. We offer a wide array of clamps for various needs, including:

• Suspension Clamps: Used to hang or suspend conductors from poles and towers, providing physical and mechanical support.

• Tension Clamps (Dead-end clamps): Designed to securely terminate a conductor at a dead-end or strain structure. These clamps are crucial for holding the full tension of the line.

• Live-Line Clamps (Hot Line Clamps): Specialized clamps for performing maintenance on energized lines without interrupting power. These clamps are made from high-strength, non-conductive materials to ensure worker safety.

Our expert sales team can help you select the most suitable clamp based on your conductor type, voltage requirements, and project specifications. We also offer customization to meet unique project needs.

Safety is our highest priority. Our equipment is manufactured to comply with international standards such as IEEE and OSHA regulations. Key safety considerations include:

• Load Ratings: Always ensure that you do not exceed the specified load ratings of the conductor grips, pulling lines, and clamps.

• Inspection: Regularly inspect all equipment, including clamps, for defects or damage before each use.

• Proper Training: All personnel involved in the stringing process must be properly trained on safe work practices, including maintaining minimum clearance distances and the correct use of tools and equipment.

• Communication: Reliable communication between the pulling rig operator and other ground personnel is essential to prevent accidents.

We provide comprehensive user manuals and technical support to ensure our customers can operate our equipment safely and efficiently.