304SE: Figure 3 shows the circuit of a simple power system,The ratings of the generators, transformers: Power Systems, Assignment, CU, Singapore

Question 3

Figure 3 shows the circuit of a simple power system. The ratings of the generators, transformers and the motors are as shown in the figure. The reactance of lines 1 and 2
are 40  and 50  respectively. Assume that system is unloaded, and the generators are generating their rated voltage. Select the generator G1 ratings as base values.

Choose the fault location for your calculations based on the last digit of your student number as indicated in the following table:

For a symmetrical three phase fault on the bus selected by you:
(i) Draw the reactance diagram for the fault with all the reactances marked in per unit.
(ii) Determine the Thevenin’s equivalent circuit which can be used to calculate the fault current.
(iii) Calculate the fault current in ampere and fault power in MVA.
(iv) Calculate the fault current contribution from the generator connected to the bus on which you have selected for fault calculation.