Interpreting Cable Fault Tester Cable Fault Causes

Cable Fault Testing System (Full Configuration) The smoothness of wired communication and power transmission depends on the normal operation of the cable line. Once the line is blocked, it will cause the communication and power to be interrupted. If the defect cannot be detected in time and eliminated quickly, it will cause great economic loss and negative social impact. Therefore, the cable fault tester is an important tool for the maintenance of various cables

Causes of failure

(1) Mechanical damage

The Cable faults caused by mechanical damage account for a high proportion of accidents. According to Shanghai statistics, the proportion of failures caused by external force mechanical damage. Some mechanical damage is so minor that it did not cause a breakdown at the time, but it took months or even years for the damage to turn intobreakdown. The main reasons for the mechanical damage of the cable are as follows:

Cable fault tester 1) Damage during installation: the cable is accidentally damaged during installation, the cable is pulled due to excessive mechanical traction or the cable is excessively damaged. Bend and damage the cable;

2) Directly damaged by external force: After installation, urban construction is carried out on the cable path or near the cable, so that the cable is directly damaged by external force;

3) Driving Vehicle vibration or impact load will cause the lead (aluminum) bundle of the underground cable to crack;

4) The damage caused by natural phenomena: such as the expansion of the insulating glue in the intermediate joint or the terminal head and the expansion of the shell or the cable sheath; due to the natural run of the cable, thecable jacket installed on the nozzle or bracket is scratched; due to excessive tension caused by land subsidence, the intermediate joint or the conductor is broken.

(2) Insulation is wet

Insulation is wet and causing failure. The main reasons why the cable must be wet are:

1) Water ingress due to unsealed structure of junction box or terminal box or improper installation;

2) Improper workmanship of the cable, metal sheath There are small holes or cracks;

3) The metal sheath is punctured by foreign objects or corroded;

(3) Aging and deterioration of insulation

Insulation of cables The air gap inside the medium dissociates under the action of the electric field to reduce the insulation. When the insulating medium is ionized, chemicals such as ozone and nitric acid are produced in the air gap, which corbreaks in the insulation; moisture in the insulation causes hydrolysis of the insulation fiber, which leads to a decrease in insulation.

Overheating can lead to aging and deterioration of the insulation. Electrical dissociation in the air gap inside the cable causes local overheating and charring of the insulation. Cable overload is a very important factor in cable overheating. Cable installation In cable-intensive areas, cable trenches, cable tunnels and other poorly ventilated places, cables passing through drying pipes and parts near cables and heat pipes will cause accelerated insulation damage due to their own overheating.

(4) Overvoltage

The effect of the atmosphere and the internal overvoltage causes the cable insulation to break to form a fault, and the breaking point is usually defective.

(5) Poor design processand workmanship

Sealed and electric field distribution design of intermediate joints and terminal heads Inadequate maintenance, poor material selection, poor workmanship and failure to meet regulatory requirements will result in the failure of the cable head.

(6) Material Defects

Material defects mainly manifest themselves in three aspects. One is the cable manufacturing problem, defects left by the lead (aluminum) sheath; during the packaging insulation process, defects such as creases, cracks, breaks and overlapping gaps appear on the insulation paper; the second is the manufacturing defects of the cable accessories, such as the cast iron parts have blisters, the mechanical strength of the porcelain parts is not enough, other parts do not meet the specifications or are not waterproof a times assembled; the thirdis poor maintenance and mismanagement of insulation materials, resulting in moisture, dirt and aging of cable insulation.

(7) Corrosion of sheath

Due to the influence of underground acid and alkali corrosion and stray currents, the lead sheath of the cable is corroded and pitted, cracked or punctured, resulting in failure.

(8) Cable insulation loss

When the oil-impregnated paper insulated cable is laid, the trench is uneven, or the outer head on the pole, in because of ups and downs. low and the large difference in height, the insulating oil in the high part flows to the low part, which reduces the insulation performance of the cable in the high place, resulting in failure.

Prev: Interpretation of why the generator battery cannot be charged