Power Systems - Online Test

Q1. A 3-bus power system is shown in the figure below, where the diagonal elements of Y-bus matrix are Y11 = -j12pu, Y22 = -j15pu and Y33 = -j7pu

The per unit values of the line reactances p, q and r shown in the figure are
Answer : Option B
Explaination / Solution:




Q2. The bus admittance matrix for a power system network is  pu
There is a transmission line, connected between buses 1 and 3, which is represented by the circuit shown in figure.

If this transmission line is removed from service, What is the modified bus admittance matrix?
Answer : Option C
Explaination / Solution:



Q3. Power is transferred 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

Answer : Option C
Explaination / Solution:
No Explaination.


Q4.
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

Answer : Option B
Explaination / Solution:
No Explaination.


Q5. Consider two buses connected by an impedance of (0+j5) Ω. The bus1 voltage is 100∠300 V, and bus2 voltage is 100∠00V. The real and reactive power supplied by bus 1, respectively, are 
Answer : Option A
Explaination / Solution:
No Explaination.


Q6. A three-phase, 33kV oil circuit breaker is rated 1200 A, 2000 MVA, 3s. The symmetrical breaking current is
Answer : Option C
Explaination / Solution:
No Explaination.


Q7. The zero-sequence circuit of the three phase transformer shown in the figure is

Answer : Option C
Explaination / Solution:
No Explaination.


Q8.
A 50Hz synchronous generator is initially connected to a long lossless transmission line which is open circuited at the receiving end. With the field voltage held constant, the generator is disconnected from the transmission line. Which of the following may be said about the steady state terminal voltage and field current of the generator?

Answer : Option A
Explaination / Solution:
No Explaination.


Q9.
A balanced star-connected and purely resistive load is connected at the secondary of a stardelta transformer as shown in figure. The line-to-line voltage rating of the transformer is 110V/220V. Neglecting the non-idealities of the transformer, the impedance ‘Z’ of the equivalent star-connected load, referred to the primary side o the transformer, is:

Answer : Option D
Explaination / Solution:
No Explaination.


Q10.
Consider a three-phase, 50Hz, 11kV distribution system. Each of the conductors is suspended by an insulator string having two identical porcelain insulators. The self-capacitance of the insulator is 5 times the shunt capacitance between the link and the ground, as shown in the figure. The voltage across the two insulators are

Answer : Option B
Explaination / Solution:
No Explaination.