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## Friday, February 15, 2019

### Electric power system (Objective Questions With Answers)

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[1]Three generators are feeding a load of 100MW.The details of the generators are
Rating(MW) Efficiency() Regulation(p.u.) on 100MVA base
Generator-1 100 20 0.02
Generator-2 100 30 0.04
Generator-3 100 40 0.03
In the event of increased load power demand, which of the following will happen? [GATE 2009]
A. All the generators will share equal power
B.Generator – 3 will share more power compared to Generator – 1
C.Generator – 1 will share more power compared to Generator – 2
D.Generator – 2 will share more power compared to Generator – 3
Ans: None of the above

[2]A 500MW, 21kV, 50Hz, 3-phase, 2-pole synchronous generator having a rated p.f. =0.9, has a moment of inertia of 27.5 x 103 kg-m2. The inertia constant (H) will be [GATE 2009]
A.2.44 s
B.2.71s
C.4.88s
D.5.42s

[3]For a fixed value of complex power flow in a transmission line having a sending end voltage V, the real power loss will be proportional to [GATE 2009]
A.V
B.V2
C.1/V2
D.1/V

[4]How many 200W/220V incandescent lamps connected in series would consume the same total power as a single 100W/220V incandescent lamps? [GATE 2009]
A.Not possible
B.4
C.3
D.2

[5]Match the items in list I with the items in list II and select the correct answer using the codes given below the lists [GATE 2009]
A. a→2,b→3,c→4,d→1
B. a→2,b→4,c→3,d→1
C. a→4,b→3,c→1,d→2
D. a→4,b→1,c→3,d→2

[6]Match the items in list I with the items in list II and select the correct answer using the codes given below the lists [GATE 2009]
A. a→2,b→1,c→3
B. a→3,b→2,c→1
C. a→1,b→2,c→3
D. a→1,b→3,c→2

[7] For the system shown below, SD1 and SD2 are complex power demands at bus 1 and bus 2 respectively. If |V2|=1pu, the VAR rating of the capacitor (QG2) connected at bus 2 is [GATE2012]
A. 0.2 pu
B. 0.268
C. 0.312
D. 0.4pu

[8] A cylindrical rotor generator delivers 0.5 pu power in the steady-state to an infinite bus through a transmission line of reactance 0.5 pu. The generator no-load voltage is 1.5 pu and the infinite voltage is 1.5 pu. The inertia constant of the generator is 5MW-s/MV and the generator reactance is 1 pu.The critical clearing angle, in degrees, for a three-phase dead short circuit fault at the generator terminal is [GATE2012]
A. 53.5
B. 60.2
C. 70.8
D. 79.6

[9] Power is transfered from system A to system B by an HVDC link as shown in the figure.If the voltages VAB and VCD are as indicated in the figure, and I>0,then
A. VAB<0,VCD<0,VAB>VCD
B. VAB>0,VCD>0,VAB>VCD
C. VAB>0,VCD>0,VAB<VCD
D. VAB>0,VCD<0

[10] Consider a step voltage wave of magnitude 1pu travelling along a lossless transmission line that terminates in a reactor.The voltage magnitude across the reactor at the instant the travelling wave reaches the reactor is
A. -1pu
B. 1pu
C. 2pu
D. 3pu