I. Preparation and inspection before installation

Before carrying out the installation of cable intermediate fusion splice joints, adequate preparation and careful inspection are essential. First of all, according to the type of cable, specifications, voltage level and the use of the environment, select the appropriate fusion joints. Different types of cables, such as power cables, communication cables, fusion joints on the electrical properties, mechanical strength and insulation requirements are different; high-voltage cables and low-voltage cables, but also need to adapt to different levels of voltage-resistant joints. At the same time, the use of the environment is also critical, in the humid, high temperature, corrosive and other special environments, should be used with the corresponding protective properties of the joints, such as waterproof, high-temperature or corrosion-resistant joints.

Second, the cable and fusion joints for a comprehensive inspection. Check whether the cable sheath is damaged, whether the internal conductor is broken, oxidation and other problems; check whether the packaging of the fusion joint is intact, whether the accessories are complete, whether there are obvious quality defects, such as broken insulation, conductor deformation and so on. Any minor defects may cause serious problems in subsequent use. In addition, you also need to prepare the tools required for installation, such as wire strippers, fusion welding equipment, cleaning tools, etc., and to ensure that the tools are good performance, accuracy meets the requirements.

Second, the standard operation of the installation process

The installation process is to ensure the quality of the cable intermediate fusion splice joints core link, must be strictly in accordance with the norms of operation. The first step is the cable pretreatment, the use of appropriate stripping tools, in accordance with the specified length and depth of the cable stripped of the outer sheath, insulation and shielding, revealing a clean, flat conductor. In the stripping process, avoid damaging the conductor, otherwise it will affect the electrical properties and mechanical strength of the joint.

The next step is conductor connection. For different types of fusion joints, the connection method varies. Mechanical connection methods need to ensure that the connector and the conductor close fit, bolt fastening strength is moderate, too loose will lead to poor contact, increased resistance, overheating and even cause a fire; too tight may damage the conductor. Thermal fusion connection should strictly control the heating temperature and time, so that the conductor is fully fused to form a solid connection. At the same time, ensure that the conductors of the two cables are in the same straight line to avoid misalignment or distortion, in order to reduce resistance and power loss.

After completing the conductor connection, carry out insulation treatment. Select and cable insulation material performance matching insulation tape or insulation sleeve, in accordance with the prescribed number of layers and winding method for wrapping, to ensure that the insulation layer is uniform, no bubbles, no wrinkles, to restore the insulating properties of the cable. For high-voltage cables, it is also necessary to carry out shielding treatment to restore the shielding layer of the cable, to ensure uniform distribution of the electric field, to prevent partial discharge.

Third, the key points in the operation and maintenance

cable intermediate fusion joint installation is completed and put into operation, the daily operation and maintenance is an important means to ensure its long-term stable work. Regular inspection is essential to check whether there is any abnormality in the appearance of the joint, such as whether the insulation layer is cracked, deformed, discoloured, whether there is any sign of overheating in the joint area (e.g., the temperature is significantly higher than that of the surrounding environment or neighbouring cables), and whether there is any corona sound or odour generated by partial discharge. Once abnormalities are found, they should be dealt with in a timely manner.

Temperature monitoring is also an important part of operation and maintenance. As the joint part is a relatively large resistance in the cable system, easy to generate heat, if the heat dissipation or contact resistance increases, it will lead to temperature rise, accelerate insulation aging, and even cause failure. Infrared thermometer and other equipment can be used to measure the temperature of the joints on a regular basis, and record the data to establish a temperature trend file, so as to detect the abnormal rise in temperature in a timely manner.

In addition, it is also necessary to pay attention to the environmental conditions in which the joints are located. Keep the environment around the joint clean and dry, avoid stagnant water and debris accumulation, and prevent corrosive gases or liquids from eroding the joint. For joints installed in the underground or tunnels, regularly check whether the drainage system is smooth, to prevent the joints from being immersed in water for a long time.

Troubleshooting and Emergency Measures

Despite all the precautions taken, cable intermediate fusion joints may still fail. When the joint is found to be faulty, first of all, to ensure personnel safety, set up warning signs in the faulty area to avoid unrelated personnel to approach, and cut off the power supply in a timely manner to prevent electrocution accidents.

Then, carry out troubleshooting. Judge the type and location of the fault through appearance inspection, insulation resistance test, DC voltage withstand test and other methods. Common faults include insulation breakdown, poor conductor connection, local overheating and so on. For insulation breakdown faults, it is necessary to check whether the insulation layer is defective, damp or aging, and if necessary, replace the damaged insulation parts; in the case of poor conductor connection, it is necessary to re-check the connection parts to ensure that the connection is tight and the resistance meets the requirements; for local overheating faults, it is necessary to analyse the causes of overheating, such as excessive contact resistance, poor heat dissipation, etc., and take corresponding measures to solve the problem.

Fault handling and emergency measures
Despite taking various preventive measures, faults may still occur at the fusion joints in the middle of the cable. When a fault is found in the joint, the first thing to ensure is the safety of personnel. Warning signs should be set up in the fault area to prevent unrelated personnel from approaching, and the power supply should be cut off in a timely manner to prevent electric shock accidents.
Then, conduct troubleshooting. Determine the type and location of the fault through visual inspection, insulation resistance testing, DC withstand voltage testing, and other methods. Common faults include insulation breakdown, poor conductor connection, local overheating, etc. For insulation breakdown faults, it is necessary to check whether the insulation layer has defects, moisture or aging, and replace damaged insulation components if necessary; If the conductor connection is poor, the connection part should be rechecked to ensure that the connection is tight and the resistance meets the requirements; For local overheating faults, it is necessary to analyze the causes of overheating, such as excessive contact resistance, poor heat dissipation, etc., and take corresponding solutions.