External Injury

Recent operational analyses indicate that, particularly in today's era of rapid economic growth, a significant number of cable failures are caused by mechanical damage.

Insulation Moisture Absorption

This situation is quite common, typically occurring at cable joints in directly buried or conduit installations. For instance, the poor quality of control cable joint manufacturing and the creation of joints under damp climatic conditions can lead to water intrusion or the mixing of steam. Over time, under the influence of the electric field, this can result in the formation of water trees, gradually impairing the insulation strength of the cable and causing malfunctions.

Chemical Corrosion

Cables buried directly in areas with acidic or alkaline effects often suffer corrosion of their armor, lead sheath, or outer sheath. The protective layer, subjected to long-term chemical or electrolytic corrosion, becomes ineffective, leading to reduced insulation and cable failures. In some cases, the extent of cable corrosion in units is quite severe.

Ongoing Long-Term Overload Operation

Overload operation inevitably leads to conductor heating as the load current passes through the cable due to the thermal effect of electricity. The skin effect of charges, as well as the eddy current losses in the steel sheath and the dielectric losses, also generate additional heat, causing the cable temperature to rise. Prolonged overload operation accelerates the aging of the insulation, eventually leading to insulation breakdown. Particularly during the hot summer months, the temperature rise often results in the first breakdown at the weakest points of the cable insulation, leading to a higher number of cable faults during this season.

Cable joint failure

Cable joints are the weakest link in cable lines, and faults caused by direct human error (poor construction) in cable jointing are often encountered. During the process of making cable joints, if issues such as loose crimping or insufficient heating occur, it can lead to a reduction in the insulation of the cable head, thereby triggering accidents.

Environment and Temperature

The external environment and heat sources surrounding the cable can also cause the cable to overheat, insulation breakdown, and even explosion and fire. Other Factors Normal aging of the cable itself or natural disasters and other causes.