A surge of 20kV magnitude travels along a lossless cable towards its junction with two identical lossless overhead transmission lines.The inductance and the capacitance of the cable are 0.4 mH and 0.5 µF per km.The inductance and capacitance of the overhead transmission lines are 1.5 mH and 0.015 µF per km.The magnitudeof the voltage at the junction due to surge is

1.  36.72 kV

2.  18.36 kV

3.  6.07 kV

4.  33.93 kV

View Answer  
4
Correct Answer :

36.72 kV


Explanation :
No Explanation available for this question

A dc distribution system is shown in the figure with load currents as marked.The two ends of the feeder are fed by voltage sources such that VP-VQ=3V.The value of the voltage VP for a minimum voltage of 220 V at point along the feeder is

1.  0225.89 V

2.  222.89 V

3.  220.0 V

4.  228.58 V

View Answer  
4
Correct Answer :

228.58 V


Explanation :
No Explanation available for this question

The bus impedance matrix of a 4-bus power system  is given by A branch having an impedance of  j0.2Ω is connected between bus 2 and the reference.Then,the values of Z22,new and Z23,new of the bus impedance matrix of the modified network are respectively.

1.  j0.5408 Ω and j0.4586 Ω

2.   j0.1260 Ω and j0.0956 Ω

3.  j0.5408 Ω and j0.0956 Ω

4.   j0.1260 Ω and j0.1630 Ω

View Answer  
4
Correct Answer :

j0.1260 Ω and j0.0956 Ω


Explanation :
No Explanation available for this question

A 20-MVA,6.6-kV,3-phase alternator is connected to a 3-phase transmission line.The per unit positive sequence,negative sequence and zero sequence impedances of the alternator are j0.1 and j0.04 respectively.The neutral of the alternator is connected to ground through an inductive reactor of j0.05 p.u.The per unit positive,negative and zero impedances of the transmission line are j0.1 and j 0.3 respectively.All per unit values are based on the machine ratings.A solid ground fault occurs at one phase of the far end of the transmission line.The voltage of the alternator neutral with respect to ground during the fault is

1.  513.8 V

2.  889.9 V

3.  1112.0 V

4.  642.2 V

View Answer  
4
Correct Answer :

642.2 V


Explanation :
No Explanation available for this question

Incremental fuel costs (in some appropriate unit) for a power plant consisting of three generating units are IC1=20+0.3P1 IC2=30+0.4P2 IC3=30 Where P1 is the power in MW generated by unit i,for i=1,2 and 3.Assume that all the three units are operating all the time.Minimum and maximum loads on each unit are 50 MW and 300 MW respectively.If the plant is operating on economic load dispatch to supply the total power demand of 700 MW,the power generated by each unit is

1.  P1=242.86 MW;P2=157.14 MW and P3=300 MW

2.  P1=157.14 MW;P2=242.86 MW and P3=300 MW

3.  P1=300.0 MW;P2=300.0 MW and P3=100 MW

4.   P1=233.3 MW;P2=233.3 MW and P3=233.4 MW

View Answer  
4
Correct Answer :

P1=242.86 MW;P2=157.14 MW and P3=300 MW


Explanation :
No Explanation available for this question

A list of relays and the power system components protected by the relays are given in Group I and Group II respectively .choose the correct match from the four choices given below: Group-I Group-II P.Distance relay 1.Transformers Q.Under frequency relay 2.Turbines R.Differential relay 3.Bus bars S.Buchholz relay 4.Shunt capacitors   5.Alternators   6.Transmission lines  

1.  P-6;Q-5;R-3;S-1

2.  P-4;Q-3;R-2;S-1

3.   P-5;Q-2;R-1;S-6

4.  P-6;Q-4;R-5;S-3

View Answer  
4
Correct Answer :

P-6;Q-5;R-3;S-1


Explanation :
No Explanation available for this question

A generator delivers power of 1.0 p.u to an infinite bus through a purely reactive network.The maximum power that could be delivered by the generator is 0.2 p.u.A three phase fault occurs at the terminals of the generator which reduces the generator output to zero.The fault is cleared after tc second.The original network is then restored,The maximum swing of the rotor angle is found to be δmax=110 electrical degree.Then,the rotor angle in electrical degrees at t=tc is

1.  55

2.  70

3.  69.14

4.  72.4

View Answer  
4
Correct Answer :

69.14


Explanation :
No Explanation available for this question

A three-phase alternator generating unbalanced voltages is connected to an unbalanced load through a 3-phase transmission line as shown in figure,the neutral of the alternator and the star point of the load are solidly grounded.The phase voltages of the alternator are Ea=10  0oV,Eb=10 -90oV,Ec=10 120oV.The positive sequence component of the load current is

1.  1.310 -107oA

2.  0.332 -120oA

3.  0.996 -120oA

4.  3.510 -81oA

View Answer  
4
Correct Answer :

0.996 -120oA


Explanation :
No Explanation available for this question

For the n-channel enhancement MOSFET shown in the figure,the threshold voltage Vtn=2V.The drain current ID of the MOSFET is 4 mA.when the drain resistance RD is 1 kΩ.if the value of RD is increased to 4Ω,drain current ID will become

1.  2.8 mA

2.  20. mA

3.  1.4 mA

4.  1.0 mA

View Answer  
4
Correct Answer :

2.8 mA


Explanation :
No Explanation available for this question

Assuming the operational amplifier to be ideal,the gain Vout/Vin for the circuit shown in the figure is

1.  -1

2.  -20

3.  -100

4.  -120

View Answer  
4
Correct Answer :

-120


Explanation :
No Explanation available for this question
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