List of top Power Systems Questions

A 3-phase star connected slip ring induction motor has the following parameters referred to the stator: \[ R_s = 3 \, \Omega, \, X_s = 2 \, \Omega, \, X_r' = 2 \, \Omega, \, R_r' = 2.5 \, \Omega \] The per phase stator to rotor effective turns ratio is 3:1. The rotor winding is also star connected. The magnetizing reactance and core loss of the motor can be neglected. To have maximum torque at starting, the value of the extra resistance in ohms (referred to the rotor side) to be connected in series with each phase of the rotor winding is \_\_\_\_\_\_ (rounded off to 2 decimal places).

In the \( (x, y, z) \) coordinate system, three point charges \( Q \), \( Q \), and \( \alpha Q \) are located in free space at \( (-1, 0, 0) \), \( (1, 0, 0) \), and \( (0, -1, 0) \), respectively. The value of \( \alpha \) for the electric field to be zero at \( (0, 0.5, 0) \) is \_\_\_\_\_\_ (rounded off to 1 decimal place).

The given equation represents a magnetic field strength \( \vec{H}(r, \theta, \phi) \) in the spherical coordinate system, in free space. Here, \( \hat{r} \) and \( \hat{\theta} \) represent the unit vectors along \( r \) and \( \theta \), respectively. The value of \( P \) in the equation should be (rounded off to the nearest integer). \[ \vec{H}(r, \theta, \phi) = \frac{1}{r^3} \big( \hat{r} P \cos \theta + \hat{\theta} \sin \theta \big) \]

If the energy of a continuous-time signal \( x(t) \) is \( E \) and the energy of the signal \( 2x(2t - 1) \) is \( cE \), then \( c \) is (rounded off to 1 decimal place).

A BJT biasing circuit is shown in the figure, where $V_{BE = 0.7V$ and $\beta = 100$. The Quiescent Point values of $V_{CE}$ and $I_{C}$ are respectively:} \includegraphics[width=0.4\linewidth]{42.png}

Let \( f(t) \) be a real-valued function whose second derivative is positive for \( -\inftyLt;tLt;\infty \). Which of the following statements is/are always true?

Consider the function \( f(t) = (\max(0, t))^2 \) for \( -\inftyLt;tLt;\infty \), where \( \max(a, b) \) denotes the maximum of \( a \) and \( b \). Which of the following statements is/are true?

The incremental cost curves of two generators (\( \text{Gen A} \) and \( \text{Gen B} \)) in a plant supplying a common load are shown. If the incremental cost of supplying the common load is \( \lambda = 7400 \, \text{Rs/MWh} \), the common load in MW is \_\_\_\_\_ (rounded to the nearest integer).
\includegraphics[width=0.5\linewidth]{34.png}

The Sequence components of the fault current in a system are as follows:
\(I_{positive}\) = j1.5p.u
\(I_{negative}\) = -j 0.5 p.u
\(I_{zero}\) = -j 1 p.u
The type of fault in a power system is_____

Match List I with List II

Choose the correct answer from the options given below:

Match List-I and List-II

LIST I		LIST II
A.	Thermal	I.	High operating cost
B.	Nuclear	II.	High capital cost
C.	Hydro	III.	High plant life
D.	Diesal	IV.	High fuel transtoortaicr cost

Choose the correct answer from the options given below:

Identify the location of fault in the power system shown in the figure below. A sustained 3-Φ fault occurred. (The voltage and current phasors, after the natural transients have died down are also shown.)

Identify the location of fault in the power system