Comparison of failure analysis of heat shrinkable and cold shrinkable cable heads

1. Failure analysis of heat-shrinkable cable head

There are three main faults that often occur in heat-shrinkable cable heads: one is easy to produce electrochemical corrosion; the other is phase-to-semiconductor discharge; the third is that the insulation layer is easily damaged.

The main cause of electrochemical corrosion is that the distance between the phases is too close, so the outer skin of the insulation is easily corroded. Since the insulating layer shielding layer of the heat-shrinkable cable head is removed more, there is no shielding layer in the place where the two phases are close, and leakage may occur. Moreover, the electric field formed at the junction is an uneven electric field, and the field strength is relatively large, causing a discharge phenomenon of air and water vapor, and an acoustic sound is emitted. The reason why the phase line causes a discharge phenomenon to the semiconductor is that the heat shrink layer is destroyed and does not have the ability to withstand the phase voltage, so the single phase will break down the insulating surface of the semiconductor layer, causing a major safety accident.

As the temperature rises, the three fingers of the cable are broken down, and the insulation layer is subjected to a huge impact. The manufacturing process requirements of the three fingers of the cable are very strict, and it is not easy to use the flame spray gun for welding.

2. Failure analysis of cold shrink cable head

There are two main types of failures of the cold-shrinkable cable head: one is that the installation operation is not standardized, the phase line is in contact with the core, and finally the phase line is broken through the shielding layer; the second is when the cable is produced, because the manufacturing process is not fine. Damage was caused to the cable. Therefore, in the process of use, the semiconductor is discharged in a damaged place, forming an uneven electric field, which is prone to accidents.

3. Analysis of other problems

Compared to the heat-shrinkable cable head, the cold-shrinkable cable head is not very good at the three fingers. In the case of sudden external force, it is very easy to escape, and the sealing property is destroyed, causing water to seep and causing moisture in the insulation layer of the cable. Moreover, if the hoop is placed at the three fingers when fixing the cable, the probability of this situation will be greatly improved.