Answer: A typical power transmission and distribution system diagram illustrates the journey of electricity from the power plant to the end user. The main components include:

• Generating Stations: Where electricity is produced.

• Step-up Transformers: Increase voltage for efficient long-distance transmission.

• Transmission Lines: High-voltage lines that transport electricity over great distances.

• Substations: Where voltage is stepped down for local distribution.

• Distribution Lines: Carry electricity at lower voltages to communities.

• Distribution Transformers: Step down the voltage to levels safe for residential and commercial use.

Our company, Ningbo Changshi, provides the critical tools and equipment for every stage of this process, from installing the high-voltage conductors on transmission lines to laying the underground cables that make up a distribution network.

Answer: An overhead power transmission line consists of several key components that work together to safely and efficiently transmit electricity. The most critical parts are:

• Conductors: The wires that carry the electric current. While copper was once common, modern transmission lines predominantly use ACSR (Aluminum Conductor Steel-Reinforced) for its optimal balance of light weight, high conductivity, and mechanical strength.

• Line Supports: Structures like steel towers or wooden/concrete poles that hold the conductors high above the ground.

• Insulators: Devices made of porcelain, glass, or polymer that prevent the current from flowing from the conductors to the supporting structures.

• Crossarms: Horizontal beams that hold the insulators and maintain the proper spacing between conductors.

• Ground Wires (Shield Wires): A wire placed at the top of the towers to protect the conductors from lightning strikes.

Ningbo Changshi provides a comprehensive range of overhead line equipment and tools specifically designed for the construction, stringing, and maintenance of these complex components, ensuring safe and reliable installation.

Answer: While both systems serve the same purpose, their components differ significantly due to their environments. Overhead lines are exposed to the elements and use bare conductors, insulators, and large support structures. Underground cables, on the other hand, are buried and require robust, insulated conductors with multiple protective layers. Key components for underground systems include:

• Insulated Conductors: Made of aluminum or copper, these are fully insulated to prevent contact with the surrounding soil or water.

• Cable Sheaths and Jackets: Protective layers of metal and plastic that shield the conductor and insulation from moisture, chemicals, and physical damage.

• Conduits and Ducts: Tubes or channels that house the cables and provide an extra layer of protection during installation and operation.

• Manholes and Handholes: Access points for laying, splicing, and maintaining the underground cables.

Our company specializes in a wide array of underground cable laying equipment and tools, which are essential for the efficient and safe installation of these specialized components.

What are the main types of power losses in a transmission and distribution system?

Answer: Reducing power line losses is crucial for improving grid efficiency and sustainability. Several strategies are employed:

1. Increasing Transmission Voltage: Transmitting electricity at higher voltages reduces the current for the same amount of power (P=VI), which significantly decreases I²R losses.

2. Using High-Quality Conductors: Selecting conductors with low resistance, such as ACSR (Aluminum Conductor Steel-Reinforced), is essential.

3. Proper Line Maintenance: Regular maintenance prevents damage to conductors and insulators that can lead to energy leakage.

At Ningbo Changshi, we provide the tools and equipment that are vital for executing these strategies. Our OHTL equipment and underground cable tools ensure that high-quality conductors are installed with the precise tension and clearances required to minimize sag, maintain proper phase spacing, and ultimately reduce I²R and corona losses. We help ensure the reliability and efficiency of your electrical infrastructure from the ground up.

Answer: An exclusion clause, particularly in legal and insurance documents related to power line easements and projects, is a provision that limits or removes a party's liability under certain conditions. For example, a property owner's liability for damage to a power line might be excluded if the damage was caused by the utility company's failure to maintain proper clearances.

This highlights the critical importance of proper construction and maintenance. By using high-quality overhead line equipment and adhering to strict industry standards, we at Ningbo Changshi help our clients build and maintain power lines that are less prone to failure and damage, thereby reducing the likelihood of liability issues. Our tension stringing equipment and tools are essential for ensuring that conductors are installed with the precise sag and tension required to maintain safe clearances and comply with all safety regulations.

Answer: Liability for power line incidents can be complex and depends heavily on the specific circumstances. While a utility company has a primary duty of care to install and maintain its lines safely, third parties can also be held liable. The key factors in determining liability often include:

• Negligence: Did a party fail to exercise reasonable care? This could be a utility company failing to repair a sagging line, or a contractor operating equipment too close to a line.

• Foreseeability: Was the accident or damage a foreseeable result of the party's actions or inactions?

• Compliance with Standards: Were all safety standards, such as the National Electrical Safety Code (NESC), followed?

We understand that our clients need equipment they can trust to meet and exceed these standards. Our OHTL tools and accessories are designed to support safe and compliant installations, helping our clients minimize the risk of accidents and litigation. We are committed to providing the best equipment to ensure the safety and reliability of power line projects globally.

Answer: While both are essential parts of the power grid, transmission lines and distribution lines serve very different functions. Transmission lines carry large amounts of electricity at extremely high voltages over long distances, typically from power plants to substations. They are often characterized by their tall steel towers and thick, bundled conductors.

Answer: The choice between overhead and underground power lines depends on a variety of factors, including cost, reliability, and aesthetics.

Overhead Power Lines

• Advantages: They are significantly less expensive to install and repair, as they are easily accessible. They also dissipate heat more efficiently.

• Disadvantages: They are more susceptible to damage from severe weather, trees, or wildlife, which can lead to frequent power outages.

Underground Power Lines

• Advantages: They are more resilient to weather-related damage and offer a more aesthetically pleasing solution by being hidden from view.

• Disadvantages: They are much more expensive to install, and locating and repairing a fault can be a time-consuming and costly process.

Our company provides a full range of solutions for both construction methods. We offer robust overhead tools and accessories for durable and efficient aerial installations, as well as state-of-the-art underground cable laying equipment designed for precise and secure trenching and installation.

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.