Professional Answer: For 220 kV overhead transmission line projects, a 180 kN stringing machine offers a significant advantage in efficiency and safety. The high pulling force is essential for stringing large, heavy conductors over long spans and challenging terrains, which are common in 220 kV projects. This capacity allows for the stringing of multiple bundled conductors simultaneously, reducing project timelines and operational costs. Furthermore, our machines are equipped with precise tension control and automatic overload protection systems, ensuring the integrity of the conductor and enhancing worker safety throughout the process.

Professional Answer: At Ningbo Changshi, we prioritize conductor integrity. Our 180 kN stringing machines utilize wear-proof bullwheels with specialized linings to minimize friction and prevent surface damage. We also adhere to the tension stringing method, which keeps the conductor elevated off the ground and away from obstacles, preventing scratches and abrasions. Our equipment includes real-time tension monitoring and load-limiting devices to ensure the pulling force never exceeds safe limits, protecting the conductor from overstressing.

Professional Answer: When selecting a 180 kN hydraulic puller/tensioner, critical features include:

• Closed hydraulic circuit: This provides infinitely variable speed and tension control.

• Automatic overload protection: An essential safety feature that automatically adjusts or stops the machine if the pulling force becomes too high.

• Negative spring-applied hydraulic release brake: This ensures the brake engages automatically in case of hydraulic failure, preventing the line from running uncontrolled.

• Real-time monitoring: A line pull gauge for continuously reading the traction force and a rope clamping device for safe reel replacement. Our machines incorporate these features, built with high-quality components from leading international brands, guaranteeing reliability and peak performance on the job site.

Answer: When considering used power line stringing equipment, it's crucial to perform a thorough inspection to ensure reliability and safety. As a leading manufacturer, we recommend you focus on the following key areas:

• Hydraulic System: Check for any leaks, visible damage to the hoses, and the overall condition of the pump and motor. A well-maintained hydraulic system is vital for smooth and consistent operation.

• Bullwheels and Grooves: Inspect the bullwheels for wear and tear, paying close attention to the condition of the lining segments. Damaged grooves can harm the conductor during the stringing process.

• Engine and Controls: Verify the engine's maintenance history and performance. Also, test all control instruments, including the dynamometer and speed counters, to ensure they are functioning correctly.

• Frame and Structural Integrity: Look for any cracks, rust, or signs of stress on the frame, axles, and trailer. This is essential for safe transport and operation.

• Safety Features: Confirm that all safety features, such as the hydraulic brakes and overload protection systems, are in proper working order.

By checking these components, you can better assess the equipment's remaining lifespan and potential repair costs.

Answer: The lifespan of power line stringing equipment can vary significantly depending on the manufacturer, frequency of use, and maintenance quality. With proper maintenance, our equipment can last for many years, often exceeding a decade. To determine the remaining life of a used machine, consider the following:

• Hours of Operation: The total hours on the engine's meter provide a good indication of its usage.

• Maintenance History: A comprehensive service record will show how well the equipment was cared for and if any major components were replaced.

• Manufacturer Support: Older equipment may no longer be supported by the original manufacturer, making it difficult to find replacement parts or get technical assistance.

• Component Wear: As mentioned in the first question, a physical inspection of key components like the engine, hydraulic system, and bullwheels will reveal the current state of the machine's health.

For new equipment, we guarantee quality and provide full technical support and spare parts. This is a significant advantage over a used machine with an unknown history.

Answer: Safety is paramount in OHTL stringing. Key precautions and equipment include:

• Proper Grounding: All stringing equipment, including pullers, tensioners, and travelers (stringing blocks), must be properly grounded to protect personnel from induced voltages and accidental energization.

• Personal Protective Equipment (PPE): All workers must use appropriate PPE, such as helmets, gloves, and safety shoes, as per local and international safety standards.

• Overpull Protection Systems: Modern hydraulic pullers and tensioners, like those we manufacture, are equipped with automatic overpull protection systems to prevent exceeding the conductor's maximum tension limits.

• Crossings: When stringing over existing energized lines or public infrastructure, temporary guard structures, such as netting or rider poles, are essential to prevent the conductor from dropping.

A1: The most common methods for laying underground cables are:

• Direct Laying: The cable is buried directly in a trench. This method is economical but has the lowest protection against mechanical damage.

• Draw-in System: Cables are pulled through ducts or conduits. This provides excellent protection and allows for future replacement or expansion without re-excavation.

• Troughing System: The cables are placed in pre-cast concrete or fiberglass troughs, which are then covered. This method offers good protection and is ideal for situations where multiple cables need to be routed together.

The draw-in system is generally considered the most reliable due to its superior protection and ease of maintenance, despite a higher initial cost. For all these methods, we offer a comprehensive range of equipment, including trenchers, cable rollers, and pulling winches, to ensure a safe and efficient installation.

A cable termination is a crucial component that makes a secure and durable electrical and physical connection between a cable and a piece of equipment or another cable. Its primary purpose is to seal the cable end, preventing moisture ingress and protecting the insulation from environmental damage, which can lead to electrical failure.

There are three main types of cable terminations we offer:

• Heat-Shrink: This type uses heat-shrinkable components that, when heated, shrink down to form a tight, protective seal.

• Cold-Shrink: These terminations are pre-expanded and simply require the user to remove a supporting core, allowing the components to shrink and fit snugly around the cable without the need for an external heat source.

• Pre-Moulded Push-On: These terminations are designed to be pushed directly onto the cable end, providing a quick and reliable connection.

Safety is paramount in all electrical work, especially with underground cable projects. Key considerations include:

• Utility Mapping: Before any excavation, conduct a thorough survey to locate and mark all existing underground utilities (gas, water, telecom, etc.) to prevent accidental damage.

• Proper Trenching: Trenches must be dug to the appropriate depth and width according to local regulations and the cable's voltage.

• Cable Protection: Use appropriate bedding (a layer of sand) and mechanical protection (tiles or marker tape) to shield the cable from sharp objects and warn future excavators of its presence.

• Proper Equipment: Use specialized equipment such as cable rollers, winches with tension control, and drum jacks to handle and install cables correctly, preventing damage from excessive pulling tension or tight bending radii.

We provide a full range of high-quality, durable equipment designed to meet international safety standards, helping to ensure your projects are completed safely and efficiently.

Safety is our top priority. The key best practices for underground cable laying include:

• Thorough Planning: Before any excavation, a comprehensive utility detection and mapping process must be performed using ground-penetrating radar (GPR) or other locators to identify existing underground services.

• Proper Trench Design: Trenches must be of sufficient depth and width, with stable walls, to prevent collapse.

• Personal Protective Equipment (PPE): All workers must use appropriate PPE, including hard hats, insulated gloves and boots, and high-visibility clothing.

• Correct Equipment Usage: Utilize specialized equipment like cable drum jacks, cable rollers, and pulling winches with tension monitoring systems to ensure that the maximum pulling tension is not exceeded, preventing cable damage and ensuring worker safety.

• Grounding and Bonding: Proper grounding and bonding are crucial to prevent electrical shock.

• Post-Installation Testing: Conduct thorough electrical testing, such as insulation resistance and continuity testing, before energizing the cables.

The required depth for burying electrical cables in a trench varies by region and voltage level. However, a general guideline is as follows:

• Low Voltage (LV) cables (< 1kV): Typically buried at a minimum depth of 450-750 mm (18-30 inches).

• Medium/High Voltage (MV/HV) cables (> 1kV): Buried deeper, typically 750-1200 mm (30-48 inches). Under roads or driveways, depths are often increased, and cables are always installed within protective ducts. The trench should also have a bedding layer of fine soil or sand to protect the cable from sharp rocks and provide a good thermal environment.

Preventing cable damage is critical for the long-term reliability of the power line. We recommend the following:

• Using the Right Tools: Employ cable rollers to guide and support the cable, minimizing friction and abrasion.

• Controlled Pulling: Use hydraulic pulling winches with tension monitoring devices to ensure the pulling force remains within the manufacturer's specified limits. Over-tensioning can stretch and damage the cable's conductors or insulation.

• Maintaining Bending Radius: Never bend a cable tighter than its specified minimum bending radius. We offer a wide range of cable laying tools to assist in maintaining these crucial parameters.

• Appropriate Lubricants: Use specialized lubricants to reduce friction when pulling cables through ducts or conduits.