Power transmission is crucial for a stable and reliable electrical grid. It ensures that electricity generated at remote power plants (such as hydro, solar, or wind farms) can be delivered to population centers and industrial areas. By transmitting electricity at high voltages, power loss is minimized, making the entire system more efficient. This infrastructure is the backbone of modern society, supporting everything from residential lighting to large-scale industrial operations. At Ningbo Changshi, we provide a full range of overhead transmission line (OHTL) wire cable conductor tension stringing equipment to ensure these vital connections are built and maintained efficiently.

A power transmission system consists of several critical components that work together to move electricity efficiently:

• Power Lines/Conductors: These are the physical wires that carry electricity. For high-voltage transmission, conductors are typically made of aluminum with a steel core for strength and are often bundled to increase capacity and reduce power loss. Our OHTL stringing equipment is specifically designed for installing and maintaining these conductors on towers.

• Transmission Towers/Structures: Large steel lattice towers or tubular steel poles that support the power lines, keeping them at a safe height above the ground.

• Insulators: Devices, often made of glass, porcelain, or polymers, that attach the conductors to the towers and prevent the electrical current from flowing to the support structure.

• Substations: These facilities contain transformers, switchgear, and other equipment to step up the voltage for transmission and then step it back down for distribution.

• Underground Cables: Used for power transmission in urban or environmentally sensitive areas where overhead lines are not feasible. We also offer comprehensive underground cable laying equipment and tools.

While both are part of the electrical grid, they serve different functions:

• Transmission moves large amounts of electricity at very high voltages (typically 69 kV to 765 kV) over long distances, from power plants to substations. It's the bulk transport of power.

• Distribution takes the high-voltage electricity from substations and steps it down to a lower, safer voltage (typically under 33 kV) for local delivery to homes, businesses, and industrial facilities. It's the final-mile delivery network.

HVAC and HVDC are two methods for transmitting large amounts of electrical power over long distances. While both are critical to the modern grid, they have distinct applications and characteristics.

• HVAC (Alternating Current): This is the most common form of power transmission. AC power lines are widely used because voltage can be easily stepped up or down using transformers, making it highly compatible with existing infrastructure. However, HVAC transmission experiences reactive power losses and is limited in distance due to the electrical characteristics of the lines, such as capacitance and inductance.

• HVDC (Direct Current): HVDC transmission carries electricity in a single direction, which makes it ideal for very long distances (over 300 km) and submarine cables. It is more efficient than HVAC over these distances because it has lower power losses and does not experience the same reactive power issues. HVDC is also used to connect different electrical grids that are not synchronized, but it requires expensive converter stations at each end of the line.

At Ningbo Changshi, we provide a full range of equipment and tools for the construction and maintenance of both HVAC and HVDC transmission lines, ensuring you have the right solutions for any project.

Power transmission and distribution are the two critical phases that deliver electricity from power plants to end-users. While both are essential, they differ significantly in their function, scale, and the challenges they face.

• Transmission: This stage is like the "interstate highway" of the electrical grid. It involves moving vast amounts of electricity at very high voltages (typically 69 kV to 765 kV) over long distances, often from power generation plants to major substations. The primary challenges in this area involve minimizing energy loss over long distances and managing the stability of the grid under high loads.

• Distribution: This is the "local road system" that takes electricity from regional substations and delivers it to homes, businesses, and factories. It operates at much lower voltages (typically 11 kV to 46 kV, with a final step-down to household voltages). Distribution is complex due to a dense network of lines and equipment, making it a key area for maintaining service reliability and responding to local power demand.

Modern Challenges and Our Solutions:

The power industry is rapidly evolving with the integration of renewable energy sources like wind and solar, which require advanced equipment to manage their variable output. Additionally, aging infrastructure and a growing demand for electricity from sources like electric vehicles and data centers are putting pressure on the entire grid.

At Ningbo Changshi Electric Power Machinery Manufacturing Limited, our high-quality equipment is designed to meet these modern challenges. We provide essential tools for:

• Upgrading aging infrastructure for both overhead and underground systems.

• Improving efficiency to reduce transmission losses.

• Building new lines to support the integration of renewable energy projects.

An electrical transmission line is a specialized network of conductors and equipment used to transport large quantities of electrical energy at very high voltages over long distances. It acts as the backbone of the power grid, connecting power generation plants (like solar farms, wind farms, or thermal power stations) to substations in cities and towns.

The purpose of a transmission line is to transmit electricity with minimal energy loss. By raising the voltage, the current is reduced, which significantly decreases energy loss due to heat over hundreds of kilometers.

The main components of an overhead transmission line include:

• Conductors: These are the wires that carry the high-voltage electricity. They are typically made of aluminum reinforced with a steel core (ACSR) for strength and are uninsulated, with air acting as the primary insulator. For higher voltages, conductors are often "bundled" into groups to increase capacity and reduce losses.

• Insulators: Made from materials like porcelain, glass, or polymers, insulators are crucial for supporting the conductors and preventing the electrical current from leaking to the support structures or the ground. They are designed to withstand extremely high voltages and environmental stress.

• Support Structures: These are the large towers or poles that hold the conductors high above the ground. Structures can be lattice steel towers for extra-high voltage lines or tubular steel poles for lower voltages and shorter distances. Our specialized equipment, such as tension stringing equipment, is essential for the safe and efficient construction of these structures.

• Ground Wires: Also known as shield wires, these are positioned at the very top of the towers to protect the conductors from direct lightning strikes by diverting the charge safely to the ground.

• Substations: These facilities are critical connection points where transformers "step up" the voltage for transmission and "step down" the voltage for distribution to consumers.

At Ningbo Changshi, we specialize in the comprehensive range of tools and equipment necessary for the construction and maintenance of these vital components, ensuring the reliability and efficiency of the global power grid.

An electrical transmission system is the extensive network of infrastructure that carries high-voltage electricity over long distances, from power generation plants to local substations. It is a critical part of the larger power grid, which also includes the local distribution system that delivers electricity to end-users. The primary goal of the transmission system is to ensure the reliable and efficient bulk transfer of power.

The process begins at a power plant where electricity is generated at a relatively low voltage. A step-up transformer immediately increases this voltage to extremely high levels (e.g., 230 kV to 765 kV). This is the key to minimizing energy loss, as higher voltage allows for less current to be used for the same amount of power, significantly reducing the heat lost in the conductors. The high-voltage electricity is then sent across the country via high-voltage transmission lines. When the power reaches a local service area, it enters a substation where step-down transformers reduce the voltage to a level suitable for the local distribution system, which then delivers it to homes and businesses.

At Ningbo Changshi, we provide a full range of high-quality wire cable conductor tension stringing equipment and hydraulic pullers that are indispensable for the construction and maintenance of these essential transmission lines.

This is a very common question, and understanding the distinction is crucial. The main differences are in their function, voltage levels, and scale:

• Function and Voltage: The transmission system is the "highway" of the power grid, moving huge amounts of power at very high voltages (over 69 kV) across vast distances. In contrast, the distribution system is the "local road network," carrying power at lower voltages (under 69 kV) from substations to individual consumers.

• Physical Infrastructure: Transmission lines are typically supported by large, steel lattice towers or tubular poles. Distribution lines, which run through neighborhoods, are usually supported by smaller wooden poles.

Ningbo Changshi is a leading manufacturer and exporter of the specialized equipment and tools required for both overhead transmission line and underground cable laying projects, serving as a one-stop solution for clients worldwide.

Public concern about living near high-voltage power lines primarily centers on the electromagnetic fields (EMF) they produce and their potential health effects. It's important to understand that EMFs are a natural part of our environment and are also emitted by many common household appliances, such as microwaves and refrigerators.

Extensive research has been conducted on this topic for decades by leading health organizations worldwide, including the World Health Organization (WHO). The general consensus is that there is no conclusive scientific evidence linking the low-level EMFs from power lines to adverse health effects. The World Health Organization has classified extremely low-frequency magnetic fields (the type from power lines) as "possibly carcinogenic to humans" (Group 2B). It is important to note that this is the third-lowest of four classifications and is based on a limited statistical association with childhood leukemia found in some studies, not a proven causal link. Other things in this same category include pickled vegetables and aloe vera extract.

The key takeaway from the scientific community is that while it is impossible to prove a negative (that there is no risk at all), the current body of evidence does not substantiate a direct health hazard from exposure to the EMF levels typically found near transmission lines.

While health risks are not scientifically substantiated, there are definitive safety risks associated with direct contact or close proximity to power lines.

• Electrocution Hazard: Transmission lines carry extremely high voltages and are uninsulated. Electricity can "arc" or "flash" over a significant distance without direct physical contact, which is why strict safety clearances are enforced.

• Safety Clearances: For professional workers and equipment, organizations like OSHA (Occupational Safety and Health Administration) in the US mandate minimum approach distances. These distances increase with the voltage of the line.

• Fallen Lines: A downed power line is extremely dangerous. The ground around it can become energized, and direct contact can be lethal.

At Ningbo Changshi, our core mission is to provide safe and reliable electrical construction and maintenance equipment. We strictly adhere to and promote international safety standards. Our products, such as tension stringing equipment and underground cable laying tools, are designed to help professionals work on these vital infrastructure projects with the highest level of safety and efficiency, ensuring the integrity of the power grid for everyone.

Electrical transmission lines are a complex system with three primary components: conductors, ground wires, and supporting structures. The choice of material for each component is crucial and depends on factors like conductivity, mechanical strength, cost, and environmental conditions.

1. Conductors: The most vital part of the line, conductors are the "wires" that carry the electricity. Historically, copper was used due to its excellent conductivity, but aluminum has become the dominant material for modern overhead lines. Aluminum is lighter and less expensive than copper, making it ideal for long-distance transmission. To overcome aluminum's lower tensile strength, various types of conductors are used:

• AAC (All-Aluminum Conductor): Made of stranded aluminum wires, these are lightweight but have lower strength. They are best suited for short-span applications.

• AAAC (All-Aluminum-Alloy Conductor): These conductors use a high-strength aluminum alloy, providing better mechanical properties and corrosion resistance, often used in coastal or high-corrosion environments.

• ACSR (Aluminum Conductor Steel Reinforced): This is the most common type for high-voltage transmission lines. It combines the high conductivity of an outer layer of aluminum strands with the exceptional strength of a central steel core. The steel core provides the necessary tensile strength to support the conductor over long spans with minimal sag.

2. Ground Wires (or Shield Wires): These wires are located at the very top of the transmission towers. Unlike conductors, they do not carry current under normal conditions. They are made of materials like steel and are designed to absorb and deflect lightning strikes, protecting the live conductors below and grounding the electrical surge safely.

3. Supporting Structures (Towers and Poles): These structures hold the conductors and ground wires at a safe distance from the ground and other objects. They are primarily made of galvanized steel in a lattice or tubular design. The use of galvanized steel ensures durability and corrosion resistance. In some cases, reinforced concrete poles or even wood poles are used, depending on the voltage level and geographical location.

At Ningbo Changshi, we specialize in providing the essential tension stringing equipment and underground cable laying equipment required to install these critical components. Our tools are designed to handle a wide array of conductor types and support structure materials, ensuring efficient and safe construction of overhead and underground power line projects worldwide.

Electrical installation refers to the entire process of setting up new power infrastructure, including the placement of overhead transmission lines (OHTL) or the laying of underground cables. This involves a series of critical, meticulously planned steps to ensure a safe, efficient, and reliable electrical system.

Electrical maintenance, on the other hand, is the ongoing care and repair of this infrastructure. It's a proactive strategy to prevent failures and address issues before they become major problems. Without proper maintenance, even a perfectly installed system will degrade over time, leading to costly and dangerous outages.

The importance of both is rooted in three key areas:

• Reliability: Regular maintenance helps identify and fix minor issues like damaged insulators or worn conductors, preventing them from causing widespread power outages. This ensures a consistent and uninterrupted power supply for communities and industries.

• Safety: Faulty equipment and degraded components pose a significant risk of fire, electrocution, and other hazards. Proper installation and ongoing maintenance are crucial for protecting both the public and the utility workers.

• Efficiency: A well-maintained power grid operates more efficiently, reducing energy loss during transmission. This not only lowers operational costs but also contributes to a more sustainable energy system.

At Ningbo Changshi, we provide the specialized equipment necessary for both the installation and maintenance phases of power line projects, from OHTL stringing to underground cable laying. Our tools are engineered to support the highest standards of safety and efficiency, ensuring that your projects meet and exceed industry requirements.

Professional Answer: Earthing, also known as grounding, is a critical safety measure in any electrical installation. Its fundamental purpose is to create a low-resistance path for fault currents to safely flow into the earth. This prevents dangerous voltages from building up on equipment casings and metal enclosures, thus protecting personnel from electric shock and safeguarding electrical equipment from damage. It ensures a stable reference point for the electrical system and helps protective devices, such as fuses and circuit breakers, to operate effectively.

Professional Answer: There are two primary classifications of earthing systems: equipment earthing and system earthing.

• Equipment Earthing refers to connecting the non-current-carrying metal parts of an electrical installation to the earth. This is a safety measure to prevent electric shock. Common methods include rod earthing, plate earthing, and strip earthing, chosen based on soil resistivity and available space.

• System Earthing involves connecting a specific point of the power system (like the neutral point of a transformer) to the earth. The most common systems are defined by IEC standards and include:

  • TN Systems: The neutral point is directly earthed at the source, and exposed conductive parts of the installation are connected to the earth via a separate protective conductor (TN-S), or a combined neutral and protective conductor (TN-C or TN-C-S).

  • TT Systems: Both the supply source and the consumer's installation are connected to separate earth electrodes. This is common in public distribution networks.

  • IT Systems: The supply source is isolated from the earth or connected via a high impedance. This is often used in industrial or critical applications where service continuity is essential, as a single earth fault will not immediately trip the system.

Professional Answer: Effective earthing requires specialized tools and equipment to ensure a reliable and low-resistance connection. Our company, Ningbo Changshi, specializes in manufacturing and exporting these essential products. Key equipment includes:

• Earthing Rods and Electrodes: These are conductive rods or plates, typically made of copper or galvanized steel, driven into the ground to create the connection to the earth.

• Earthing Conductors and Cables: High-quality, corrosion-resistant conductors that connect the electrical system's metal parts to the earth electrodes.

• Earth Clamps and Connectors: Used to securely bond conductors to equipment, structures, and earthing rods, ensuring a robust electrical connection.

• Portable Earthing and Short-Circuiting Kits: These are crucial safety tools for maintenance and repair on high-voltage power lines and substations. They temporarily ground the conductors to prevent accidental energization and discharge any residual charge.

• Telescopic Operating Rods: Insulated rods used to apply and remove portable earthing kits from a safe distance.

Optical Ground Wire (OPGW) is a multi-functional cable used in overhead power transmission lines. It combines the traditional function of a ground wire with the advanced capabilities of a fiber optic cable. The metallic components of the OPGW provide lightning protection and a grounding path, shielding the high-voltage conductors from surges. Simultaneously, the embedded optical fibers enable high-speed data transmission for telecommunications, monitoring, and control of the power grid. Essentially, it serves as the "eyes and ears" of the power line, ensuring both physical protection and a robust communication network.

The primary advantage of OPGW is its dual functionality, which offers significant benefits over a conventional ground wire. By integrating fiber optics into the ground wire, OPGW provides a cost-effective solution for power utilities to establish a reliable communication network without the need for separate infrastructure. It enhances system reliability by enabling real-time monitoring, fault detection, and smart grid applications. This also improves efficiency by allowing for remote control and data transmission, and the robust construction ensures long-term durability against environmental stresses like wind, ice, and electrical faults.

OPGW cables are primarily used by the electric utility industry on high-voltage overhead transmission lines. Their applications include:

1. Telecommunications: They provide a high-speed path for voice, video, and data transmission for the utility's internal use and can also be leased to third-party telecommunication companies, generating additional revenue.

2. Smart Grid Integration: OPGW serves as the communication backbone for smart grid technologies, facilitating data exchange for better monitoring, control, and efficiency.

3. SCADA Networks: It is essential for Supervisory Control and Data Acquisition (SCADA) systems, which are used to remotely monitor and control equipment at substations.

4. Retrofit Projects: OPGW is a popular choice for replacing existing traditional ground wires on older transmission lines to modernize the infrastructure.

An OPGW cable is a complex, meticulously engineered structure. At its core, it contains one or more tubular units, typically made of stainless steel or aluminum, that house the delicate optical fibers. These tubes are filled with a water-blocking gel to protect the fibers from moisture. This central unit is then surrounded by layers of metallic wires, such as aluminum-clad steel or aluminum alloy. These outer layers provide the necessary mechanical strength, electrical conductivity for grounding, and protection from lightning strikes and other environmental factors, while safeguarding the internal fibers from mechanical and thermal stress. The design ensures the integrity of the optical signals even under high-voltage conditions.