Symmetrical and unsymmetrical faults

Symmetrical, unsymmetrical faults and symmetrical components

1. Symmetrical and unsymmetrical
faults

2. Agenda
•Type of faults ( symmetrical and unsymmetrical faults)
•Symmetrical components (positive, negative, and zero
sequences)
•Using Matlabsimulation to see the difference between faults

3. Type of faults
1-Symmetrical faults
A-Three phase fault to ground (L.L.L.G).
B-Three phase fault (L.L.L).2-Unsymmetrical faults
A-Line to ground fault (L.G)
B-Line to line fault (L.L)
C-Line to line to ground fault (L.L.G)

4. Symmetrical faults
A-Three phase fault (L.L.L).
B-Three phase fault to ground (L.L.L.G).

5. Unsymmetrical faults
A-Line to ground fault (L.G) B-Line to line fault (L.L)

6. Unsymmetrical faults
C-Line to line to ground fault (L.L.G)

7. Symmetrical components
1-Positive sequence.
2-Negative sequence.
3-Zero sequence.

8. 1-Positive sequence.
Va1= 1/3(Va+aVb+a²Vc)

9. 2-Negative sequence.
Va2= 1/3(Va+a²Vb+aVc)

10. 3-Zero sequence.
Va0= 1/3(Va+Vb+Vc)

11. Grounding of transformer and
generator during unsymmetrical faults

12. Thank you for watching