In the scorching summer heat, power outages caused by cable faults are a real ordeal. Furthermore, fires caused by cable faults are extremely intense and spread rapidly, producing large quantities of harmful gases and making them difficult to extinguish. Repairs to damaged cables can be time-consuming and costly, making it crucial to prioritize preventing cable fires. Below, we'll explain the causes and maintenance considerations for high-voltage cable failures.
Causes of High-Voltage Cable Failures
① Site conditions are relatively poor. Cables and connectors are manufactured in factories with strict environmental and process requirements, and temperature, humidity, and dust levels are difficult to control at the construction site.
② During installation, technical procedures and regulations were not strictly adhered to, and potential problems were not considered. Final acceptance testing involved a DC withstand voltage test, which resulted in a reverse electric field at the joints, causing insulation damage.
③ Poor sealing. Intermediate joints must utilize a metal copper shell with a polyethylene or polyvinyl chloride insulation and anti-corrosion coating to ensure the tightness of the on-site lead seal, effectively ensuring the joint's sealing and waterproof properties.
④ During cable construction, small slip marks inevitably remain on the insulation surface, and semiconductor particles and sand from the emery cloth may become embedded in the insulation. Furthermore, because the insulation material is exposed to air during joint construction, moisture can be absorbed into the material, posing a risk to long-term safe operation.
⑤ Defects are inevitable in the cable material itself, cable manufacturing, laying, and terminal fabrication. Due to the influence of electrical, thermal, chemical, and environmental factors during operation, the cable insulation will experience varying degrees of aging, which can ultimately lead to cable failure.
Precautions and Maintenance Methods for High-Voltage Cable Maintenance
① Improve maintenance techniques. Do not use sharp knives to cut excess or thick insulating rubber to avoid cuts. Instead, use a wood file to gradually refine the high-voltage cable rubber layer. Do not use a file that has been used on metal materials to file the cable. This prevents fine metal particles from penetrating the insulating rubber layer, causing high-voltage static electricity and potentially damaging the high-voltage cable rubber and cable plugs.
② The cable grounding grid must be securely fastened to the high-voltage cable plug to avoid static sparks caused by cold solder joints. Before welding, clean the welding area and apply a layer of tin. Solder quickly to avoid burns to the insulating rubber and potential breakdown.
③ For older high-voltage cables, the base of the cable plug socket may bend due to aging and cable quality. Therefore, breakdown often occurs in these stress-bending locations. During maintenance, a steel sleeve can be added to the upper end of the plug socket to reduce breakdown damage caused by stress bending at the cable base.
④ The insulating rubber layer and the inner wall of the cable plug must be clean and free of any dirt. Use an electric hair dryer to remove any moisture before welding.
⑤ Avoid using fillers that are too hot, which may damage or deform the insulating rubber or plastic.
⑥ Improve the insulating filler in high-voltage cable plugs. After years of trial use, a mixture of 75% transparent rosin and 25% high-quality transformer oil, heated and mixed, has proven to be effective.
⑦ Avoid hard bending and heavy stress on high-voltage cables. When hanging high-voltage cables, use curved, circular hangers. Do not hang them directly from hooks or by tying them together.
⑧ To prevent moisture and mold from forming, high-voltage cables should be hung; using cable trenches is not recommended.
⑨ Damp-damaged high-voltage cables should be dried in a drying oven or a constant-temperature oven before use.
Everyone should know that safety is paramount when it comes to power cables. While high-voltage cables are known to pose significant risks, household electrical wiring is no exception. Long-term use can lead to aging, so regular maintenance and inspection are essential. Home wiring should not be overloaded, as this can easily cause short circuits and, in severe cases, fires. For your own safety, it's crucial to prioritize the repair and maintenance of your electrical cables.
