Causes of Cable Collapse During Operation

In recent years, cable accidents have occurred a lot, causing many fire accidents, including PVC housing wire, CU/PVC electric wire, and XLPE copper power cable.

There are many reasons why cables are broken down during operation. 

The main reason is the reduction of insulation strength and the damage from external forces. 

There are several reasons for this:

1 If the cable is overloaded for a long period of time, the expansion oil pressure will be generated due to the increase in the oil temperature, and the lead pack of the cable will be stretched. 

when the load is reduced and the cable temperature is lowered, a gap will be formed inside the lead package of the cable. 

These voids are easily detached under the action of an electric field, which deteriorates the insulation performance and causes cable breakdown.

2 In addition, overload operation accelerates the insulation's aging and shortens the cable's life.

3 The cable head oil leakage damages the sealing so that the insulating oil is dry and moisture intrusion. 

When the moisture in the cable insulation increases from 0.3% to about 0.7%, the electrical strength decreases by an average of 20% to 25%. 

At this time, the insulation resistance changes more significantly, which is one of the main reasons for the breakdown of the cable.

4 External force damage includes external mechanical damage and tension caused by topographical changes. 

In addition, there are some hidden dangers (such as bumps, sprains, etc.) caused during manufacturing or laying.

5 If the accidental injury has been grounded or short-circuited, the damage does not seem serious at the time, but it may be broken down after a period of operation.

6 The protective layer is invalid. 

The lead wire of the cable and the steel shovel and hemp skin outside the lead skin also have their life. 

After a long time, the hemp will fall off, and the steel shovel and lead skin will be corroded so that they will lose their protection to the insulation layer and eventually be broken down. 

Of course, this has a lot to do with external conditions. 

The external conditions are good, the use time is extended, the external conditions are not good, and the service life is short.