Answer: An overhead transmission line system consists of several crucial components that work together to safely and efficiently transport electricity. The primary components are:

• Conductors: The wires that carry the electrical current. They are typically made from materials like aluminum with a steel core for strength, a product known as Aluminum Conductor Steel Reinforced (ACSR).

• Towers/Pylons: These are the tall structures that provide mechanical support for the conductors, keeping them at a safe height above the ground.

• Insulators: Devices that physically separate the conductors from the towers, preventing the flow of electricity to the support structure. They are commonly made of porcelain, glass, or polymer composite materials.

• Hardware and Fittings: A wide variety of clamps, connectors, dampers, and other accessories used to secure the conductors to the insulators and towers.

Ningbo Changshi specializes in manufacturing a complete range of overhead transmission line equipment, overhead tools, and accessories, including conductor tension stringing equipment, insulator stringing tools, and various clamps and connectors to ensure the safe and reliable construction and maintenance of these systems.

Answer: Transmission lines can be classified based on their voltage, length, and physical location.

• Based on Voltage: Transmission lines are categorized as High Voltage (HV), Extra High Voltage (EHV), and Ultra High Voltage (UHV), with each class having a specific voltage range.

• Based on Length: They are also classified as Short, Medium, and Long lines, with the analysis of each type considering different electrical parameters.

• Based on Physical Location:

  • Overhead Transmission Lines: These are the most common type, with conductors suspended in the air by towers.

  • Underground Transmission Lines: Insulated cables that are buried in trenches or tunnels, typically used in densely populated urban areas or for short distances where overhead lines are not feasible.

  • Submarine Cables: A specialized type of underground cable laid on the seabed to connect power grids across bodies of water.

As a leading manufacturer, Ningbo Changshi provides all the necessary equipment for these different line types, from overhead transmission line equipment for traditional grid projects to underground cable laying equipment for modern infrastructure development.

Answer: The Ferranti effect is a phenomenon where the receiving-end voltage of a long AC transmission line becomes higher than the sending-end voltage under light load or no-load conditions.

This happens because the line's distributed capacitance generates leading reactive power, which is greater than the lagging reactive power consumed by the line's inductance. This excess reactive power causes a voltage rise along the line. It's a significant concern because this overvoltage can damage sensitive equipment like transformers and insulation at the receiving end of the line.

Answer: To counter the Ferranti effect, the excess reactive power generated by the line's capacitance must be absorbed. The most common and effective method is by installing shunt reactors at the receiving end of the transmission line.

A shunt reactor is an inductive device that absorbs reactive power, effectively compensating for the capacitive effect of the line. By installing these devices, we can regulate the voltage and maintain it within safe operating limits.

Ningbo Changshi offers a full range of Overhead Transmission Line Equipment and Underground Cable Laying Equipment, including accessories and tools for the installation and maintenance of such compensation devices. Our products ensure the reliable operation of your power systems, even in the presence of challenging phenomena like the Ferranti effect.

Answer: The proximity effect is a phenomenon in which the alternating current (AC) in a conductor is redistributed due to the magnetic field of a nearby, current-carrying conductor. The interacting magnetic fields between adjacent conductors cause the current to crowd into specific areas of the conductor's cross-section.

If two conductors carry current in the same direction, the current is pushed to the outer, remote halves of the conductors. If the currents are in opposite directions, the current is concentrated on the inner, closer halves. This uneven distribution of current increases the effective resistance of the conductor, leading to greater power losses and heating.

Answer: The magnitude of the proximity effect is influenced by several factors:

• Frequency: The effect is more pronounced at higher AC frequencies.

• Conductor Diameter: A larger conductor diameter leads to a more significant effect.

• Conductor Spacing: The effect increases as the distance between adjacent conductors decreases.

• Conductor Material: Materials with higher magnetic permeability are more susceptible.

To reduce the proximity effect, several strategies can be employed. The most common and effective method, especially in overhead transmission lines, is to increase the spacing between conductors. Using bundled conductors (two or more conductors per phase) is another popular method. This configuration not only increases the effective conductor spacing but also improves the efficiency of the line.

At Ningbo Changshi, we provide a comprehensive range of overhead line tools and accessories that support the installation and maintenance of bundled conductor systems, helping our clients minimize the proximity effect and maximize transmission efficiency.

A 765 kV transmission line is a type of Extra High Voltage (EHV) power line designed to transmit massive amounts of electricity over long distances with minimal power loss. The use of such a high voltage is a strategic solution to meet the rising global demand for electricity, driven by industrial electrification and the integration of large-scale renewable energy sources. By using 765 kV, power can be moved more efficiently, reducing line losses and strengthening grid reliability. It is a critical backbone for modernizing power infrastructure and ensures a stable power supply for growing populations and industrial hubs worldwide.

Corona discharge is an electrical phenomenon that occurs in high-voltage AC transmission lines, especially those operating at 200kV and above. It is a partial discharge of electrical energy into the surrounding air, leading to a noticeable hissing sound, a blue-violet glow, and the generation of ozone. This phenomenon results in power loss and can cause electromagnetic interference.

To mitigate corona discharge and its negative effects, a common industry solution is the use of bundled conductors. Instead of using a single large conductor per phase, multiple smaller conductors are used in a bundle. This increases the effective diameter of the conductor, which in turn reduces the electric field intensity at the surface, thereby suppressing corona formation.

Ningbo Changshi manufactures and exports high-quality overhead transmission line equipment and stringing equipment that are essential for the safe and efficient installation of bundled conductors and other anti-corona solutions.

The skin effect is a property of AC transmission where the current tends to flow through the outer surface ("skin") of the conductor rather than being evenly distributed throughout its cross-section. This is due to the varying magnetic fields produced by the alternating current.

This effect significantly increases the effective AC resistance of the conductor, leading to higher I2R (Joule effect) losses and a reduction in transmission efficiency. The skin effect is more pronounced at higher frequencies and with larger conductor diameters.

To combat this, the industry is increasingly adopting advanced conductors, which are engineered with composite cores to allow for more uniform current distribution and higher capacity. Our company provides the specialized tools and equipment required for the safe and precise stringing and maintenance of these modern conductors, helping to improve the overall efficiency and lifespan of the transmission line.

The Ferranti effect is a phenomenon in long, high-voltage AC transmission lines, particularly those over 250 km, where the receiving-end voltage is higher than the sending-end voltage under light-load or no-load conditions. This is caused by the line's inherent shunt capacitance and series inductance, which generate a capacitive charging current.

Effective management of the Ferranti effect is critical for maintaining stable grid operation. The primary solution is to utilize reactive power compensation to absorb the excess reactive power. This is typically achieved by installing shunt reactors at the receiving end of the line.

As experts in electrical construction and maintenance, we provide the necessary tools and equipment to support the installation and upkeep of such complex systems. Our comprehensive one-stop supply service ensures that our clients have access to all the necessary tools for constructing and maintaining stable and efficient AC transmission networks.

As a premier manufacturer and exporter, Ningbo Changshi provides a comprehensive range of ACDs tailored for various applications. Our product line includes:

• Barbed Wire Coils: A simple yet effective physical deterrent.

• Spiked Collars & Brackets: Durable, spiked rings or guards designed to fit around poles and pipes, creating a difficult barrier.

• Half-Moon ACDs: Modular, crescent-shaped guards that can be combined to fit poles of different diameters, a common solution for many utility poles.

• Anti-theft Fasteners: We also offer specialized anti-theft bolts and nuts, like the double-ball hex anti-theft lock nut, which are used to secure ACDs and other tower components, preventing tampering and theft of valuable materials.

These devices can be customized to suit various pole materials and dimensions, including wood, steel, and concrete.

A thorough risk assessment is a key part of power line maintenance and construction. The need for an ACD is typically determined by evaluating several factors, including:

• Location and Land Use: Towers located near schools, residential areas, public parks, or other high-traffic areas are considered "high-risk."

• Structure Design: Structures with features that could be used as climbing aids, such as attached equipment, horizontal crossbars, or closely-spaced "H" poles, often require an ACD.

• Proximity to Obstacles: Any nearby features like fences, walls, or trees that could provide a foothold for an unauthorized person will also necessitate an ACD.

Our ACDs are designed to provide a reliable solution for these high-risk areas, ensuring compliance with safety standards and offering peace of mind.

A power transmission system is the backbone of the electrical grid, moving electricity from generation plants to substations for local distribution. The key components that make this possible include:

• Transmission Lines: The high-voltage cables, typically strung on tall towers or poles, that carry electricity over long distances with minimal loss.

• Substations: These facilities contain transformers and switchgear to step up the voltage for efficient long-distance transmission and then step it down for distribution to local areas.

• Transformers: Crucial devices in substations that change the voltage of the electricity. Step-up transformers increase voltage at the generation side, and step-down transformers decrease it at the distribution side.

• Insulators: These devices are essential for preventing the high-voltage wires from shorting out to the support structures or to each other. They are typically made of glass, porcelain, or composite polymer materials.

• Support Structures: This includes the towers, poles, and gantries that physically hold the transmission lines in the air, maintaining a safe clearance from the ground and other objects.