Our Professional Answer: At Ningbo Changshi, we understand that the choice of underground cable laying method depends on the project's specific needs, environment, and budget. The two primary methods are trenching and trenchless installation.

• Trenching (Direct Burial): This traditional method involves excavating a trench, laying cables in a protective sand bed, and then backfilling. It is cost-effective and straightforward for open areas. Essential equipment includes trenchers, cable rollers, and specialized cable pullers to ensure the cable is laid without exceeding its minimum bending radius or pulling tension.

• Trenchless Installation (Horizontal Directional Drilling - HDD): This method is ideal for urban areas, crossing roads, or sensitive environments where surface disruption must be minimal. It involves boring a pilot hole and then pulling the cable through a protective duct. This requires specialized HDD equipment, including drilling rigs and reamers, as well as high-strength cable pulling ropes and swivels to handle the high tensions involved in long pulls.

Our company manufactures and exports a full range of equipment and tools for both methods, providing comprehensive solutions for any project.

Our Professional Answer: Safety and efficiency are paramount for successful underground cable projects. Based on global best practices, we advise the following:

1. Thorough Planning: Before any work begins, a detailed survey of the route is essential to locate existing underground utilities. This prevents accidental damage and ensures compliance with regulations.

2. Proper Trench Design: Trenches must be dug to the correct depth and width, as dictated by local standards and the cable's voltage. This ensures the cable is protected from physical damage and has adequate spacing for heat dissipation.

3. Use of Correct Equipment: Employing the right tools is critical. This includes using cable rollers to minimize friction and prevent damage to the cable's insulation, and cable pulling winches with dynamometers to monitor and control pulling tension.

4. Backfilling and Protection: After laying, the cable should be surrounded by a protective layer of sand or fine soil before backfilling. Additionally, placing warning tape above the cable serves as a crucial visual alert for future excavation work.

By adhering to these practices and utilizing high-quality, reliable equipment, our clients can ensure the long-term reliability and safety of their underground electrical infrastructure.

Our Professional Answer: Reducing friction is one of the most critical factors in underground cable installation. Excessive friction can cause the pulling tension to exceed the cable's maximum allowable limit, leading to damage to the cable's sheath and internal conductors. This can compromise the cable's lifespan and lead to costly repairs or failures.

To mitigate this risk, our clients rely on specialized tools and materials:

• Cable Rollers: These are placed inside the trench or conduit to support the cable and allow it to be pulled smoothly. We offer a variety of rollers, including corner rollers and straight rollers, designed to accommodate different cable sizes and routes.

• Cable Lubricants: High-performance, water-based lubricants are applied to the cable as it is pulled. These lubricants significantly reduce the coefficient of friction, allowing for longer pulls and reducing the strain on both the cable and the pulling equipment.

• Cable Pulling Winches: Our hydraulic and diesel-powered pulling winches are equipped with tension measurement systems to ensure the pulling force remains within safe limits. This precise control is vital for preventing cable damage and ensuring a safe, efficient installation.

Using the right combination of rollers, lubricants, and controlled pulling equipment ensures the integrity of the cable and a successful installation.

Answer: Selecting the right laying-up machine is crucial for a project's efficiency and cable quality. At Ningbo Changshi, we offer a range of machines to suit diverse needs.

• Planetary Laying-up Machines are ideal for producing large-section, round-core power cables with minimal back-twist, ensuring a stable and high-quality final product.

• Cradle Laying-up Machines are highly versatile, often used for a wide range of cables from power to communication. They offer a good balance of speed and precision, with options for both rigid and planetary operation.

• Drum Twister Laying-up Machines are designed for high-voltage and extra-high-voltage cables. Their primary advantage is the ability to handle very large take-up drums, increasing production efficiency for long-length cables and conductors.

The best choice depends on your specific production requirements, including cable type, size, and required speed. Our sales team can provide a detailed consultation to help you choose the perfect machine.

Answer: Modern cable laying-up machines from Ningbo Changshi are equipped with advanced features designed to maximize productivity and ensure superior cable quality. Key features to look for include:

• Advanced Control Systems: Integrated PLC and HMI systems for easy pitch adjustment, real-time monitoring, and automatic synchronization of the entire production line.

• Independent Motor Drives: This provides greater control over each component of the machine, reducing maintenance, and allowing for higher rotation speeds.

• Precision Tension Control: Our machines utilize advanced tension control systems to maintain consistent wire tension, which is essential for producing uniform, high-quality cables.

• Robust and Stable Design: A sturdy frame and large bearing support, instead of traditional tugboat supports, ensure operational stability and reliability even at high speeds.

These features not only enhance performance but also contribute to lower energy consumption and a longer machine lifespan.

Safety is our top priority. We emphasize several best practices:

• Pre-installation planning: Thorough site surveys, risk assessments, and identifying existing underground utilities are crucial.

• Proper equipment: Using the correct, well-maintained tools such as hydraulic drum jacks, winches, and cable rollers is non-negotiable.

• Tension control: Monitoring and limiting the pulling tension to prevent cable damage using dynamometers and breakaway links.

• Personal Protective Equipment (PPE): All workers must wear appropriate PPE, including insulated gloves, safety glasses, and hard hats.

• Training: Our staff is extensively trained in proper cable handling techniques and emergency response procedures.

We employ several techniques to protect cables:

• Bending radius: We meticulously adhere to the cable's minimum bending radius specifications to avoid damage to the insulation and conductors.

• Lubrication: Using appropriate cable lubricants to reduce friction when pulling cables through ducts and conduits.

• Cable rollers: We use a variety of cable rollers to guide the cable smoothly around bends and through the trench, preventing scraping and kinking.

• Tension monitoring: Our pulling equipment is equipped with tension monitoring systems to ensure the force applied never exceeds the cable's safe pulling limits.

Post-installation testing is crucial to verify the integrity and safety of the cable. We recommend conducting key tests before energization, including insulation resistance testing to check for electrical leakage and high-potential (Hi-Pot) testing to assess the cable's ability to withstand high voltage. For locating faults after installation, tests like the Murray Loop test can be used to pinpoint the exact position of a fault without extensive digging.

Safety is paramount. Key considerations include:

• Personal Protective Equipment (PPE): Ensuring all personnel wear appropriate gear, including safety helmets, insulated gloves, and shock-proof boots.

• Equipment Safety: Using only insulated and tested tools and ensuring all machinery, such as winches, has safety features like breakaway links or tension monitors.

• Site Management: Following strict procedures for excavation near existing utilities, implementing Lockout/Tagout (LOTO) procedures, and using warning signs and barriers to protect workers and the public.

A successful cable laying project follows a systematic process. The key stages include:

• Planning & Design: Thorough route inspection, engineering calculations for pulling tension and sidewall pressure, and obtaining all necessary permits.

• Site Preparation: Excavation of trenches or installation of cable trays and conduits.

• Cable Installation: The actual laying and pulling of cables using specialized equipment such as winches, rollers, and drum jacks to ensure the cable is not overstressed.

• Termination & Jointing: Making secure connections at switchgear, panels, and other equipment.

• Testing & Commissioning: Post-installation tests like insulation resistance (IR) and high-potential (Hi-Pot) testing to verify the cable's integrity before it is energized.

To prevent cable damage, it is crucial to adhere to specific best practices. This includes using specialized cable rollers to reduce friction and kinking, maintaining the cable's specified minimum bending radius at all times, and applying suitable lubricants. Most importantly, a tension monitoring system must be used with a pulling winch to ensure that the maximum pulling tension is never exceeded, which can stretch or damage the cable's insulation and conductors.