Brief Introduction (Cable Faults)

When the electrical energy is get produced in the generations’ stations, then it will pass round to the different loads, i.e. towns, cities and villages for utilization then. The process require stepping up voltage to the minimize the mislaying of energy in  form of heat. The stepped up voltage is pass round to the grid stations where it will stepped down for handling out to the local transformers where this will be  finally stepped down and pass round to the clients.

Handling out of the electrical energy is completed via the electrical cables. All cables are either the insulated or un-insulated. The alternative of using the insulated or un-insulated (Overhead lines or the Underground) cables are largely near into play when the energy is to be moved in the underground installation process.

                                                 Cable-faults

Far from the insulated cables, The faults in un-insulated cables are simply detected as the most basic fault that is associated with such kind of cable is break and cut in the  wire or cable conductors.

in the insulated cables principally multi-core cables, the faults in the cables are of different kinds and have so many causes. Before we take a look that how to locate all these repeatedly met faults, let’s catch  what are the mainly cable faults  and the possible outcomes causes and just  locating of these faults.

Different kinds of Cable Faults:-

                                                   Cables-Fault.

These all are the types of Cable Faults that is mostly often Found In the underground Cables.

Open-Circuit Faults: This kind of fault mainly occurs as a final output of the conductor breaking down or the conductor being draw out of its joint. In such cases, there will be no possibility to flow of current at all as conductor is broken down.

Short-circuit or cross fault: In the short -circuit or cross fault these type of fault are mainly occurs when the insulation get damaged between two cables or between the two multi-core cables. In these kind of cases, the current flow will not be through the main core that  is connected to the load but it will flow through directly from one cable to the another one or from one core or the multi-core cable to the other instead. This load will be the short circuited.

Ground or earth faults: The Ground or earth faults are kind of faults that mostly occurs when the cable insulation gets damaged. The cable current flowing through its faulty cable that is starts flowing from the one core of the cable to the earth or the sheath of the cable. the flow of Current will not through the load then.

The reason of Cable Faults:-

The reason of Cable Faults that occurs are mainly due to the dampness in the paper insulation of the cables. As an outcome, it may destruction the lead sheath that protects the cable.Lead sheath may destruct in many other ways. Mainly of them are all chemical action of the soil on the lead when it ‘sburied, mechanical destruction and crystallization of lead far side of

How to Locate underground Faults in a Cable?

Before the fixing of any fault in the cables, We need to be identified the fault

A  regular proceed towards to the test cable and decide the insulation integrity is to take a Hi-pot test. In the hi-pot test, a Direct Current voltage will be register for 5 to 15 min. IEEE-400 state that the hi-pot voltage for the 15-kV class cable will be 56 kV for a receiving  test and 46 kV for the maintenance test (ANSI/IEEE Std. 400-1980). The rest of the industry standard tests will be given in (AEIC CS5-94, 1994; AEIC CS6-96, 1996; ICEA S-66-524, 1988). High-pot testing is just like a brute-force test; in this the imminent failures are found and detected, but the quantity ofthe  deterioration due to aging will not quantized (go/no-go test).

The Another alternative for cable testing integrity is an ac testing that doesn’t debase the solid dielectric insulation The hold of very small frequency AC testing (at respecting the 1 Hz) may be the reason of the little damage to aged cable than are Direct Current testing i.e..Eager et al., 1997(but utilities have announce this will not be completely  benign, and an alternate current testing has not obtain widespread usage).