STUPIDSID
1 (a)
In a three phase four wire system the currents in the lines a, b and c under abnormal conditions of loading were as follows:
Ia=100 ∟ 30° A, Ib=50 ∟300° A, Ic =30 ∟180° A
Calculate the zero, positive and negative phase sequence currents in line a and the return current in the neutral conductor.
Ia=100 ∟ 30° A, Ib=50 ∟300° A, Ic =30 ∟180° A
Calculate the zero, positive and negative phase sequence currents in line a and the return current in the neutral conductor.
7 M
1 (b)
Prove that per unit impedance of transformer is the same whether computed from primary or secondary side. Draw per unit equivalent circuit of single-phase transformer.
7 M
2 (a)
Explain Zbus formulation using current injection technique.
7 M
Answer any two question from Q2 (b) or Q2 (c)
2 (b)
Explain procedure of formation Ybus using singular transformation. Derive the necessary equations.
7 M
2 (c)
Explain the computation procedure of load flow by Fast decoupled load flow method.
7 M
Answer any two question from Q3 (a), (b) or Q3 (c), (d)
3 (a)
Derive the swing equation of a synchronous machine swinging against an infinite bus.
7 M
3 (b)
Derive expression for sequence impedances of a transmission line and draw their sequence networks.
7 M
3 (c)
Explain point by point method for solving swing equation.
7 M
3 (d)
Explain in detail "phase shift in star delta transformer" for positive and negative sequences voltages.
7 M
Answer any two question from Q4 (a), (b) or Q4 (c), (d)
4 (a)
Describe briefly the principle of operation of load dispatch organization coordinating different types of power plants in a power system.
7 M
4 (b)
What are the conditions to be satisfied before a 3-phase alternator is synchronized to infinite bus bars?
7 M
4 (c)
What is economics dispatch? Derive condition for economics dispatch when generating stations are connected in parallel.
7 M
4 (d)
Discuss the effect of speed-load characteristics of the prime movers on the load sharing of two alternators connected in parallel.
7 M
Answer any two question from Q5 (a), (b) or Q5 (c), (d)
5 (a)
Explain double line-to-ground fault. Write terminal conditions at fault location. Derive expression of fault current and draw the connection of sequence networks.
7 M
5 (b)
Discuss the short circuit algorithm for large system.
7 M
5 (c)
Explain line-to-ground fault. Write terminal conditions at fault location. Derive expression of fault current and draw the connection of sequence networks.
7 M
5 (d)
A 50 MVA, 11 kV, 3-phase alternator was subjected to different types of faults. The fault currents were: 3-phase fault 1870 A, line to line fault 2590 A and single line to ground fault 4130 A. The alternator neutral is solidly grounded. Find the reactance value of the three sequence reactance of the alternator.
7 M
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