Page 176 - Practical Power System and Protective Relays Commissioning

176 Practical Power System and Protective Relays Commissioning

FIGURE 16.18 Single phase to earth fault.

FIGURE 16.19 Phase-to-phase fault.

Calculations:

Z total 5 10.2 1 (10.2 1 ((0.4 1 4 1 8.2) 3 12.8)/(0.4 1 4 1 8.2 1 12.8))
5 26.25%
I 1 5 I 2 5 I 0 5 10,000/(Z%) 5 10,000/26.25 5 381 MVA
I F 5 I 1 1 I 2 1 I 0 5 3 3 381 5 1143 MVA
I F 5 MVAF/kV 3 1.732 5 1143/(132 3 1.732) 5 4.999 kA