Which among the following is related to unsymmetrical faults?
Right Answer is:
All of these
The fault in the power system is generally categorized into two type
- Symmetrical fault
- Unsymmetrical fault
The symmetrical faults are often known as balanced faults. In case of balanced faults, all three transmission lines are affected equally, and the system remains in the balanced condition. These types of faults are rare in the power system, and it contributes 2 % to 5 % of the total fault. These faults are easy to analyze. The symmetrical faults are classified as three lines to ground fault (LLLG) and three lines fault (LLL). The connection diagrams of symmetrical faults are shown in Fig. If the fault impedance, Zf = 0, then the fault is known as a solid or bolted fault.
The faults in the power system network which disturb the balanced condition of the network are known as unsymmetrical faults. The unsymmetrical faults are classified as the
(i) Single line to ground faults (SLG)
(ii) Double line to ground faults (DLG 10%)
(iii) Line to line faults (LL 15%).
More than 90 % of faults that occur in a power system are single line to ground faults. The connection diagrams of different types of unsymmetrical faults are shown in Fig.