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Fault finding and analysis of power cables!
Release Time：
2024-04-03
Mechanical damage is mainly caused by physical collisions, pulling, and other reasons for cable damage. According to relevant statistical data, mechanical damage is the most common cause of cable failures, which can be classified as follows.
The causes of power cable faults
Mechanical damage
Mechanical damage is mainly caused by physical collisions, pulling, and other reasons for cable damage. According to relevant statistical data, mechanical damage is the most common cause of cable failures, which can be classified as follows. Firstly, cable breakage is directly caused by external forces, with common causes being damage caused by construction operations or transportation; Secondly, improper operation during the installation process may cause cables to be bumped, pulled, or excessively bent; The last type is due to natural conditions, where the middle or terminal joints of the cable are subjected to natural tension and internal insulation glue expands, resulting in the rupture of the cable protective sleeve and causing fault problems.
Insulation moisture
The insulation dampness of power cables mainly refers to the insulation dampness caused by external water vapor entering the intermediate or terminal joints of power cables due to poor sealing. In addition, if the quality of the cable is poor, defects such as small holes or cracks on the protective sleeve can also cause the cable to become damp.
Cable overheating
In practical situations, the occurrence of air gap ionization inside the insulation of power cables can cause local overheating of the insulation, leading to cable insulation carbonization. Installing in areas with dense cables or poor ventilation, as well as in areas close to thermal pipelines, can cause cables to overheat. In addition, prolonged operation of power cables under overload conditions can also lead to cable overheating.
2、 Analysis and Summary of Common Power Cable Fault Points
Short circuit or grounding power cable fault
Short circuit fault is a common fault problem during the operation of power cables. There are two types of short circuit faults: high resistance short circuit fault and low resistance short circuit fault. When a short circuit fault occurs in the cable, it will cause the fuse in the cable protection device to melt and trip. Due to the fuse being blown, it will cause the cable insulation to be burnt by high temperature. At this time, the fault point of the power cable is a short circuit fault. The grounding faults of power cables are also divided into low resistance grounding faults and high resistance grounding faults. Ground fault and short circuit fault are different, and there is a significant difference between the two types of ground fault, which can be clearly divided through tools and the nature of the fault.
In general, low resistance grounding faults need to be detected using low-voltage bridges with a grounding resistance less than 20-100 Ω, while high resistance grounding faults need to be detected using high-voltage bridges with a resistance value greater than 100 Ω. In practical situations, if a grounding fault occurs, the power system's dedicated grounding detection device will send a fault signal, and the leakage protection device will also control the system to trip.
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