Causes of aging of customized electric wire cable in china

1）. External force damage of customized electric wire cable in china. According to the operation analysis in recent years, a considerable number of customized electric wire cable in china failures are caused by mechanical damage.

2）. The insulation of customized electric wire cable in china is affected with moisture. This situation is also very common, and generally occurs at the cable joints in the direct burial or pipe. For example, if customized electric wire cable in china joints are not made up to standard or are made in a humid climate, water will enter the joints or water vapor will be mixed into the joints. After a long time, water tree will be formed under the action of electric field, which will gradually damage the insulation strength of customized electric wire cable in china and cause failures.

3）. Chemical corrosion. customized electric wire cable in china are directly buried in areas with acid and alkali effects, which will often cause the armors, lead skins or outer protective layers of customized electric wire cable in china to be corroded. The protective layer is subject to chemical corrosion or electrolytic corrosion for a long time, which will lead to the failure of the protective layer, the reduction of insulation, and cable failure. The corrosion of customized electric wire cable in china in the unit is quite serious.

4）. Long term overload operation of customized electric wire cable in china. During overload operation, due to the thermal effect of the current, when the load current passes through customized electric wire cable in china, it will inevitably lead to conductor heating. At the same time, the skin effect of the charge, the eddy current loss of the steel armor and the insulation medium loss will also produce additional heat, which will increase the temperature of customized electric wire cable in china.

5）. Customized electric wire cable in china connector failure. Customized electric wire cable in china joint is the weakest link in the cable route. Customized electric wire cable in china joint failures caused by direct negligence of personnel (poor construction) often occur. In the process of making customized electric wire cable in china joints, if there are reasons such as untight crimping and insufficient heating of the joints, the insulation of the cable head will be reduced, which will lead to accidents.

6）. Environment and temperature. The external environment and heat source where the customized electric wire cable in china are located will also cause excessive temperature of customized electric wire cable in china, insulation breakdown, and even explosion and fire.

2、 Common faults of customized electric wire cable in china

Common faults of customized electric wire cable in china include mechanical damage, insulation damage, insulation damp, insulation aging and deterioration, overvoltage, cable overheating, etc. When the above fault occurs to the line, the power supply of the fault cable shall be cut off, the fault point shall be found, the fault shall be checked and analyzed, and then the repair and test shall be carried out. The power supply can be restored only after the fault is eliminated.

The most direct cause of customized electric wire cable in china failure is breakdown due to insulation degradation

It mainly includes:

a. Overload operation Long term overload operation will increase the temperature of customized electric wire cable in china, aging the insulation, resulting in insulation breakdown and reducing the construction quality

b. The electrical aspects include: the construction process of customized electric wire cable in china head fails to meet the requirements, the sealing of customized electric wire cable in china head is poor, moisture invades the interior of customized electric wire cable in china, and the insulation performance of customized electric wire cable in china decreases; When laying customized electric wire cable in china, protective measures are not taken, the protective layer is damaged, and the insulation is reduced

c. In terms of civil engineering, the drainage of the pipe trench of the well is not smooth, and customized electric wire cable in china are soaked in water for a long time, which damages the insulation strength; The working shaft is too small, the bending radius of the cable is not enough, and the cable is damaged by the external force of extrusion for a long time. It is mainly due to the mechanical barbaric construction in the municipal construction, which damages and breaks the customized electric wire cable in china

d. Corrosion. The protective layer is subject to chemical corrosion or customized electric wire cable in china corrosion for a long time, resulting in the failure of the protective layer and the reduction of insulation

e. The quality of customized electric wire cable in china itself or cable head accessories is poor, the sealing of customized electric wire cable in china head is poor, and the insulation glue is dissolved and cracked. The resonance phenomenon in the station is that the line break fault makes the line interphase capacitance and ground capacitance form a resonance loop with the excitation inductance of the distribution transformer, thus triggering ferromagnetic resonance.

3、 Harm of Resonance Caused by Broken customized electric wire cable in china
In serious cases of broken line resonance, the superposition of high frequency and fundamental frequency resonance can make the overvoltage amplitude reach 2.5 times of the phase voltage [P], which may lead to the displacement of the system neutral point, overvoltage of windings and conductors, and in serious cases, insulation flashover, lightning arrester explosion, and electrical equipment damage In some cases, the phase sequence of the load transformer may reverse, and the overvoltage may also be transmitted to the low-voltage side of the transformer, causing harm.

The main measures to prevent the resonance overvoltage of customized electric wire cable in china disconnection are:

(1) No fuse is used to avoid open phase operation

(2) Strengthen line patrol and maintenance to prevent wire breakage

(3) Do not hang the no-load transformer on the line for a long time

(4) Loop network or dual power supply is adopted

(5) Add interphase capacitance at the distribution transformer side,

Its principle is that capacitors are used as energy absorbing elements to absorb energy in the transient process, so as to reduce the intensity of impact disturbance and suppress the occurrence of resonance S - (o+3C,,) 1C, The interphase capacitance △ C is added at the distribution transformer side to increase 8 - [Co+3 (C U+A0)/Ca, so that the capacitance value required to increase the equivalent capacitance C and the equivalent electromotive force Eo can be calculated according to the method in [6].

(6) The use of transformers with better excitation characteristics will help reduce the probability of broken line overvoltage.