The material for a conductor is chosen based on a balance of several key properties: high conductivity, low weight, high tensile strength, and low cost.

• Aluminum: Aluminum is the most widely used material for power line conductors. Although it has lower conductivity than copper, it is significantly lighter and less expensive. This makes it an ideal choice for long-distance overhead transmission, as it reduces the weight and cost of the supporting towers.

• Steel: Steel is used for its high tensile strength. While it has poor electrical conductivity, it is often used as a reinforcing core to provide mechanical strength to a conductor.

• Copper: Copper has excellent conductivity and high tensile strength. However, due to its high cost and density, it is typically used only for specific applications like underground cables or in distribution lines with shorter spans.

Conductors are manufactured in various types to meet specific requirements for strength and conductivity. The most common types for overhead lines are:

• ACSR (Aluminum Conductor Steel Reinforced): This is the most prevalent type of overhead conductor. It consists of a central steel core for mechanical strength and outer strands of aluminum for electrical conductivity. This combination provides a high strength-to-weight ratio, allowing for long spans with minimal sag. Our hydraulic tensioners and pullers are designed to handle the high tensions required for installing ACSR conductors.

• AAC (All-Aluminum Conductor): Made entirely of aluminum strands, AAC conductors are lightweight and cost-effective but have lower tensile strength. They are typically used for low-voltage distribution lines with shorter spans.

• AAAC (All-Aluminum Alloy Conductor): This conductor uses an aluminum alloy for increased strength, providing a better strength-to-weight ratio than AAC. It's often used in coastal or high-corrosion environments.

• HTLS (High-Temperature Low-Sag) Conductors: These are advanced conductors designed to operate at much higher temperatures than standard ACSR, which allows them to carry more current. They use composite or high-strength alloy cores to minimize sag even when heated.

For overhead transmission line projects, a method called tension stringing is used to install conductors. This process keeps the conductor elevated off the ground to prevent damage. This requires a coordinated system of specialized machinery.

• Hydraulic Pullers: A hydraulic puller is a machine with one or more bullwheels that pull a steel pilot line or conductor at a constant, controlled force. It's the "engine" of the stringing operation, providing the pulling power to install the conductor over long spans.

• Hydraulic Tensioners: A hydraulic tensioner applies a constant back-tension to the conductor as it's pulled. This prevents the conductor from sagging and touching the ground or other obstacles, ensuring a safe and damage-free installation. Many modern machines, like ours, combine the puller and tensioner into a single unit.

• Conductor Stringing Blocks: These are pulley-like devices that are installed on tower arms. They guide the conductor along the route and around bends, minimizing friction and protecting the conductor from scrapes or damage.

• Hydraulic Drum Stands & Trailers: These are used to safely lift, support, and unspool large conductor reels. They ensure the conductor feeds smoothly into the tensioner or puller.

Underground cable laying involves pulling cables through conduits, ducts, or trenches. The equipment used is designed for confined spaces and high friction.

• Underground Cable Pullers: Also known as cable winches, these machines are specifically designed for pulling cables through ducts and manholes. They provide a controlled pulling force and often include a rope drum for winding the pulling rope. Our machines are designed with real-time tension monitoring to prevent over-tensioning.

• Cable Rollers: Used in trenches and manholes, cable rollers reduce friction and guide the cable around bends and corners. They protect the cable from abrasions and are critical for preventing damage during long pulls.

• Cable Drum Jacks & Stands: Similar to their overhead counterparts, these tools are used to lift and support heavy cable drums at the start of a pull, ensuring a smooth and controlled pay-out of the cable.

• Cable Pulling Grips & Swivels: A cable pulling grip (or sock) is a woven steel mesh sock that attaches securely to the cable's end. A swivel is a rotating joint placed between the grip and the pulling rope, preventing the cable from twisting as it's pulled, which can cause internal damage.

A conductor pulling grip is a flexible, reusable tool made of woven steel or wire mesh. Its primary function is to provide a secure, temporary connection between a conductor and a pulling rope or winch line. It's designed to distribute the pulling force evenly over the conductor's surface, preventing damage, kinking, or slippage during installation.

The grip tightens its hold on the conductor as tension is applied, creating a strong mechanical bond. This allows for a smooth, controlled pull, which is crucial when installing conductors over long distances or through confined spaces like conduits.

Pulling grips are categorized based on their construction, eye type, and intended application.

• By Weave Type:

  • Single Weave: Used for lighter, shorter pulls.

  • Double or Triple Weave: Provides greater strength and durability for heavy-duty applications, such as high-voltage overhead transmission lines.

• By Eye Type:

  • Single Eye: This is the most common type, with a single loop at the end for attachment to a swivel or pulling line.

  • Double Eye (or Double Loop): Allows for multiple cables to be pulled simultaneously.

  • Rotating Eye: Designed with a built-in swivel to prevent twisting forces from the pulling line from being transferred to the conductor.

• By Application:

  • Closed-Mesh Grips: The most secure type, where the grip is pre-woven closed at the end. The conductor is pushed into the mesh.

  • Split-Mesh (Lace-Up) Grips: These have an open mesh with laces or fasteners, allowing them to be installed on a conductor that is already partially installed or has no open end.

Selecting the correct pulling grip is crucial for a safe and successful installation. There are three key factors to consider:

1. Conductor Type and Diameter: The grip's bore or diameter range must perfectly match the conductor's outside diameter. A grip that is too large will slip, while one that is too small can damage the conductor's insulation or strands.

2. Required Holding Strength: The grip's maximum rated load must be greater than the maximum pulling tension anticipated. It is a best practice to select a grip with a rated capacity that is at least 5 times the estimated working load (a 5:1 safety factor).

3. Application Environment: For underground pulls through conduits with many bends, a rotating-eye grip with a swivel is essential to prevent twisting. For overhead projects, a heavy-duty, double-weave grip is required to handle the high tension loads.

As a prominent manufacturer and exporter, Ningbo Changshi offers a wide range of conductor pulling grips for various applications. We ensure our products meet international standards for strength and durability, providing a one-stop solution for your overhead and underground projects.

A conductor pulling rope is a specialized rope or braided cable used to pull a conductor or cable during installation. It connects the pulling machine (a hydraulic puller or winch) to the conductor, serving as the "link" that transfers the pulling force. It must be strong, durable, and resistant to twisting and abrasion to ensure a safe and efficient pull. Pulling ropes are considered a critical safety component of any installation project.

Pulling ropes are primarily classified by their material, each offering distinct advantages for different applications.

• Anti-Twisting Braided Steel Wire Rope: This is the industry standard for overhead tension stringing. It's specially braided from multiple strands of high-strength, high-flexibility galvanized steel wire. The braided design prevents the rope from twisting under tension, ensuring a smooth pull and preventing damage to the conductor. It's the ideal choice for long-distance, high-tension pulls.

• High-Strength Synthetic Ropes: These are often used for underground cable laying and medium-voltage overhead projects. Made from materials like double-braided polyester or High Modulus Polyethylene (HMPE), they are lightweight, have very low stretch, and are resistant to moisture and chemicals. Their non-conductive properties make them a safer option for certain environments.

Choosing the correct pulling rope is crucial for safety and project efficiency. Here are the key factors to consider:

1. Tensile Strength: The rope's minimum breaking strength (MBS) must be significantly higher than the maximum anticipated pulling force. A safety factor of at least 4:1 is recommended, meaning the rope's MBS should be four times the maximum working load of the pulling machine.

2. Anti-Twisting Properties: For overhead tension stringing, an anti-twisting braided rope is non-negotiable. This prevents the transfer of torque from the pulling machine to the conductor, which can cause severe kinking and damage.

3. Application Environment: Consider the environment. For overhead work, a heavy-duty steel rope is best. For underground projects, a lightweight, flexible synthetic rope is often preferred as it's easier to handle and less prone to corrosion in wet environments.

As a prominent manufacturer and exporter, Ningbo Changshi offers a wide selection of pulling ropes, including galvanized anti-twisting steel ropes and high-strength synthetic ropes. Our products are designed to meet strict international standards, providing a complete and reliable one-stop solution for your projects.

A successful tension stringing operation requires a coordinated system of specialized equipment working in unison.

1. Preparation:

   • Pilot Line Installation: A lightweight, non-conductive rope (pilot line) is first pulled across the spans, often by a drone or manually. This rope is then used to pull the heavier, anti-twisting steel pulling rope.

   • Equipment Setup: A hydraulic tensioner is positioned at one end of the section with the conductor reel, and a hydraulic puller is set up at the other end.

2. The Pull:

   • The hydraulic puller starts to pull the steel wire rope, which is connected to the conductor by a specialized conductor pulling grip and a swivel to prevent twisting.

   • Simultaneously, the hydraulic tensioner applies a controlled back-tension to the conductor. This is the key to the entire process, as it keeps the conductor elevated and taut as it moves through the stringing blocks (sheaves) on the tower arms.

3. Sagging & Termination:

   • Once the conductor is fully installed in the section, the tension is adjusted to achieve the pre-calculated sag. This is a crucial step that ensures the conductor's safety clearances are met and the tension is within safe limits for the supporting structures. Our sagging scopes are used for this.

   • Finally, the conductor is secured to the dead-end towers with tension clamps, and the temporary stringing blocks are replaced with final suspension clamps.

As a premier manufacturer of power line tools, we offer the full suite of equipment required for tension stringing.

• Hydraulic Pullers and Tensioners: These are the core machines that apply and control the pulling and braking forces. Our models feature precise, real-time tension monitoring to prevent over-stressing the conductor.

• Conductor Stringing Blocks: These are durable, high-quality sheaves that allow the conductor to glide smoothly over towers, reducing friction and protecting its surface.

• Anti-Twisting Braided Steel Ropes: These ropes are specifically designed to prevent torque buildup from the pulling machine from transferring to the conductor.

• Conductor Pulling Grips and Swivels: These accessories provide a secure, non-damaging connection between the rope and the conductor, with swivels preventing twisting and kinking.

By using the right tools and following the tension stringing methodology, crews can ensure the integrity of the conductor and the long-term reliability of the electrical system.

An OHTL (Overhead Transmission Line) conductor is a specialized cable designed to transmit electrical energy through the air, supported by towers or poles. Unlike underground cables, OHTL conductors are typically uninsulated or "bare," and their design must balance several critical factors:

1. High Electrical Conductivity: To minimize energy loss during transmission.

2. High Tensile Strength: To withstand the conductor's own weight, wind, ice, and other environmental loads over long spans.

3. Light Weight: To reduce the structural load on the supporting towers and poles, which lowers construction costs.

The material of an OHTL conductor is a strategic compromise between these factors. While copper has higher conductivity, aluminum is the preferred material due to its much lower weight and cost.

Conductors are manufactured in various types to meet specific requirements for strength, conductivity, and corrosion resistance. The most common types for OHTL are:

• AAC (All-Aluminum Conductor): Made entirely of aluminum strands, AAC conductors are lightweight and cost-effective. They have excellent conductivity and are highly resistant to corrosion. Due to their lower tensile strength, they are typically used for low-voltage distribution lines with shorter spans.

• ACSR (Aluminum Conductor Steel Reinforced): This is the most prevalent type of overhead conductor. It consists of a central steel core for mechanical strength and outer layers of aluminum strands for electrical conductivity. This composite structure provides an excellent strength-to-weight ratio, allowing for long spans and high-tension applications. Our hydraulic tensioners and pullers are specifically designed to handle the high tensions required for installing ACSR conductors.

• AAAC (All-Aluminum Alloy Conductor): This conductor is made from a high-strength aluminum-magnesium-silicon alloy. It offers better mechanical strength and improved sag characteristics compared to AAC, along with excellent corrosion resistance. This makes it a great choice for coastal regions or where a stronger conductor than AAC is needed without the steel core.

The correct conductor choice is paramount for the safety, reliability, and economic viability of a power line project.

• Sag and Tension: The weight and strength of the conductor directly impact the sag and tension of the line. Using the wrong conductor can lead to insufficient ground clearance (too much sag) or excessive tension, which can damage the conductor and towers.

• Cost Efficiency: The choice of conductor influences the number of towers needed. A stronger conductor (like ACSR) can be strung over longer spans, reducing the number of towers and the overall project cost.

• Environmental Factors: For corrosive environments (e.g., coastal areas), a conductor like AAAC with high corrosion resistance is essential for longevity.

By understanding these distinctions, professionals can make informed decisions. Ningbo Changshi is a one-stop supplier of the specialized tools and equipment required to handle all types of OHTL conductors, from the lightweight AAC to the high-strength ACSR.

A distribution line conductor is the final stage of the power delivery network, responsible for carrying electricity from a substation directly to homes, businesses, and other end-users. Unlike high-voltage transmission conductors that span vast distances, distribution conductors operate at lower voltages and typically have shorter spans. Their design focuses on balancing cost, safety, and reliability for local, often densely populated, areas.

The choice of conductor for distribution lines is often based on the specific application, whether it's an urban, suburban, or rural environment.

• Bare Conductors: These are uninsulated conductors, and their safety relies on the air clearance between the conductor and surrounding objects. They are common in rural areas with fewer trees or buildings.

  • AAC (All-Aluminum Conductor): Made entirely of aluminum strands, AAC is lightweight and cost-effective. It is an excellent choice for short-span lines where weight and cost are the primary considerations.

  • AAAC (All-Aluminum Alloy Conductor): This conductor uses a high-strength aluminum alloy, offering better mechanical strength than AAC. It is widely used in distribution lines where strength and corrosion resistance are needed.

  • ACSR (Aluminum Conductor Steel Reinforced): While also used for transmission, the ACSR conductor is a popular choice for distribution as well, especially where longer spans or higher tensions are required. The steel core provides extra mechanical strength to withstand heavy loads from wind and ice.

• Covered Conductors: These are conductors with a protective polymeric covering. They are a popular choice in environments with a higher risk of accidental contact, such as urban areas with many trees.

  • Spacer Cable System: This system consists of multiple covered conductors held in a tight configuration by insulating spacers. This allows for closer spacing and a more compact line, reducing the risk of faults caused by trees or animals.

  • Aerial Bundled Cable (ABC): This is a bundle of covered conductors twisted together with a bare neutral. ABC is used to create a highly compact and safe line, minimizing the risk of a phase-to-phase short circuit.

The primary differences stem from their function and operating environment:

• Voltage and Current: Distribution conductors carry lower voltage and current than transmission conductors.

• Span Length: Distribution lines typically have much shorter spans between poles compared to the long-distance, high-tension spans of a transmission line.

• Safety and Environment: Distribution lines are closer to populated areas, making safety and resilience against environmental factors (e.g., trees, animals) a top priority. This is why covered conductors and ABC are popular for distribution.

Ningbo Changshi offers a full range of tools and equipment for the installation of all types of distribution conductors. From our hydraulic pullers and tensioners to our specialized stringing blocks for bundled cables, we provide the reliable solutions needed to ensure the safety and efficiency of your distribution line projects.