The Seven Causes Of Cable Faults

In large and complex power grids, cable faults such as power outages and leakage frequently occur due to factors including production quality issues, improper construction, and inadequate operation and maintenance. Timely and accurate diagnosis of cable fault locations, followed by prompt troubleshooting and power restoration, has become a critical task for power management departments.

 

The Seven Causes Of Cable Faults

 

 

In large and complex power grids, cable faults such as power outages and leakage frequently occur due to factors including production quality issues, improper construction, and inadequate operation and maintenance. Timely and accurate diagnosis of cable fault locations, followed by prompt troubleshooting and power restoration, has become a critical task for power management departments.

 

The most direct cause of cable faults is insulation breakdown due to degraded insulation. Based on practical operational experience, Yancheng cable material manufacturers summarize the main factors leading to insulation degradation into the following seven categories:

 

1. Mechanical Damage

 

Analysis of recent operational data, particularly in rapidly developing areas like Shanghai Pudong, shows that a significant number of cable faults originate from mechanical damage. Examples include: improper handling during cable laying and installation, which can cause physical damage; and civil engineering work over directly buried cables, which often damages live cables. In less severe cases, damage may take months or even years to develop into a breakdown at the damaged site; in severe cases, short circuits may occur immediately, directly impacting the safe production of power users.

 

2. Insulation Moisture Ingress

 

This issue commonly occurs at joints of directly buried or duct-installed cables. For instance, poorly manufactured cable joints or jointing work performed in humid conditions can allow water or water vapor to enter. Over time, under electric field stress, "water treeing" forms, gradually deteriorating the cable’s insulation strength and leading to faults.

 

3. Chemical Corrosion

 

Cables directly buried in areas with acid or alkali contamination often suffer corrosion of their armor, lead sheaths, or outer protective layers. Prolonged exposure to chemical or electrolytic corrosion causes protective layer failure, reduced insulation, and eventual cable faults.

 

4. Long-Term Overload Operation

 

Overload operation generates heat due to the thermal effect of current: conductor heating from load current, combined with skin effect in conductors, eddy current losses in steel armor, and dielectric losses in insulation, collectively raise cable temperature. Sustained overloads accelerate insulation aging, eventually leading to breakdown. This is particularly pronounced in hot summers, when elevated temperatures often cause breakdown at weak insulation points first—explaining the higher frequency of cable faults during this period.

 

5. Cable Joint Failures

 

Cable joints are the weakest links in cable systems, with faults often caused by human error during construction. Issues such as loose crimping or insufficient heating during joint fabrication can reduce joint insulation, directly triggering accidents.

 

6. Environmental and Thermal Factors

 

External environmental conditions and heat sources can cause excessive cable temperatures, insulation breakdown, and even explosion or fire.

 

7. Natural Aging or Natural Disasters

 

Normal aging of cable components or unforeseen natural disasters also contribute to insulation degradation and subsequent faults.