Introduction to factors affecting the service life of wire and cable

- Oct 13, 2019-

The main reason that affects the service life of wire and cable is the aging failure of wire and cable, and the most direct cause of aging failure is the breakdown of insulation performance. There are many factors that lead to the reduction of insulation performance. According to the actual operating experience, the following relevant factors can be summarized for your reference:

1. External force damage factors

From the operational analysis in recent years, especially in cities with rapid economic development, quite a number of cable faults are now caused by mechanical damage. For example, when the cable is laid and installed, the construction is not standardized, which is easy to cause mechanical damage. It is also very easy to damage the cable during operation when the civil construction is carried out on the directly buried cable. Sometimes if the damage is not serious, it will take several months or even a few years to cause the damage to be completely broken down to form a fault. Sometimes the damage may be short-circuited, which may directly affect the safe production of the unit.

2, insulation moisture factor

This is also common and occurs generally at cable joints in direct buried or drained pipes. For example, if the cable joint is unqualified and the joint is made under humid climatic conditions, the joint will be filled with water or mixed with water vapor. Over time, water branches are formed under the action of the electric field, which gradually damages the insulation strength of the cable and causes malfunction.

3. Chemical corrosion factors

The cable is directly buried in an acid-base area, which often causes the cable armor, lead or outer sheath to be corroded. The protective layer is chemically corroded or electrolytically corroded for a long time, causing the protective layer to fail and the insulation to be lowered. Cable failure.

4. Long-term overload operation factors

Overload operation, due to the thermal effect of the current, the load current will inevitably lead to the conductor heating when passing through the cable. At the same time, the skin effect of the charge and the eddy current loss of the steel crucible and the loss of the insulating medium will also generate additional heat, thereby increasing the cable temperature. In the case of long-term overload operation, too high a temperature will accelerate the aging of the insulation, and the insulation will be broken down. Especially in the hot summer months, the temperature rise of the cable often leads to the breakdown of the cable insulation first, so in the summer, the cable failure is particularly high.

5, cable connector failure factors

Cable joints are the weakest link in cable lines, and cable joint failures caused by direct personnel failure (poor construction) often occur. During the process of making the cable joints, if the joints are not tightly pressed or insufficiently heated, the insulation of the cable heads will be reduced, causing an accident.

6, environmental and temperature factors

The external environment and heat source where the cable is located can also cause excessive cable temperature, insulation breakdown, and even an explosion.