Govt Exams Mock Test FREE | Online Quiz Competition

Q1. The bus admittance matrix of as simple four bus system is shown in fig. is given as

\(Y_{bus}=\begin{bmatrix}1-j3 & 0 & -1+j3 & 0\\0 & 1.666-j5 & -0.666+j2 & -1+j3\\-1+j3 & -0.666+j2 & 3.666-j11 & -2+j6\\0 & -1+j3 & -2+j6 & 3-j9\end{bmatrix}\)

The shunt admittance at all the buses is assumed to be negligible. If the line of admittance \((2-j6)\) p.u. is connected between bus 1 and bus 2. The new bus admittance matrix is

\(Y_{bus}=\begin{bmatrix}3-j9 & -2+j6 & -1+j3 & 0\\-2+j6 & 3.666-j11 & -0.666+j2 & -1+j3\\-1+j3 & -0.666+j2 & 3.666-j11 & -2+j6\\0 & -1+j3 & -2+j6 & 3-j9\end{bmatrix}\)

\(Y_{bus}=\begin{bmatrix}3+j3 & 0 & -1+j3 & 0\\0 & 3.666+j1 & -0.666+j2 & -1+j3\\-1+j3 & -0.666+j2 & 3.666-j11 & -2+j6\\0 & -1+j3 & -2+j6 & 3-j9\end{bmatrix}\)

\(Y_{bus}=\begin{bmatrix}3-j9 & 0 & -1+j3 & 0\\0 & 3.666-j11 & -0.666+j2 & -1+j3\\-1+j3 & -0.666+j2 & 3.666-j11 & -2+j6\\0 & -1+j3 & -2+j6 & 3-j9\end{bmatrix}\)

\(Y_{bus}=\begin{bmatrix}3+j3 & 2-j6 & -1+j3 & 0\\2-j6 & 3.666+j1 & -0.666+j2 & -1+j3\\-1+j3 & -0.666+j2 & 3.666-j11 & -2+j6\\0 & -1+j3 & -2+j6 & 3-j9\end{bmatrix}\)

Q2. A transmission line of 210 km length has certain values of A, B, C, D. If the length is made 100 km, then the parameter

A increases and B decreases

A and B both decrease

A and B both increase

A decreases and B increases

Q3. A 3-phase transmission line is being supported by three disc insulators. The potentials across top unit (i.e., near to the tower) and middle unit are 8 kV and 12 kV respectively. Calculate the ratio of capacitance between pin and earth to the self-capacitance of each unit.

0.5

1.5

0.66

0.33

Q4. A lightning stroke current of 10 kA strikes a line of 400 \(\Omega\) surge impedance. What is the over voltage caused when a direct stroke occurs over the top of an unshielded transmission line?

6000 kV

4000 kV

8000 kV

2000 kV

Q5. A string type insulator has \(4\) units with self capacitance \(C\) and shunt capacitance of \(0.3 \times C\). Find the string efficiency.

83.50%

90%

75%

70%

Q6. A shunt capacitor at 100 MVAr is operated at 105% of its rated voltage and at 98% of its rated frequency. The reactive power produced by the capacitor is

108.045 MVAr

112.5 MVAr

102.9 MVAr

88.899 MVAr

Q7. If the inductance and capacitance of a system are 1 H and 0.01 μF respectively and the instantaneous value of the current interrupted is 10 A, the value of the shunt resistance across the breaker for critical damping is

5 kΩ

50 kΩ

10 kΩ

80 kΩ

Q8. Determine the ohmic value of the current limiting reactor per phase external to a 30 MVA, 11 kV, 50 Hz, three phase synchronous generator which can limit the current on short circuit of 5 times the full load current. The reactance of the synchronous generator is 0.05 pu.

\(0.405\:\Omega\)

\(0.805\:\Omega\)

\(0.305\:\Omega\)

\(0.605\:\Omega\)

Q9. The parameters of a transposed overhead transmission line are given as: self reactance \(X_S=0.4\) ohm/km and mutual reactance \(X_m = 0.1\) ohm/km. The positive and zero sequence reactance respectively, in ohm/km are

0.3, 0.2

0.5, 0.2

0.5, 0.6

0.3, 0.6

Q10. Reflection coefficient of current \(R_I\) is, (\(Z_l =\) Surge impedance of load, \(Z_s =\) Surge impedance of line)

\(\frac{2 Z_s}{(Z_s + Z_l)}\)

\(\frac{2 Z_l}{(Z_s + Z_l)}\)

\(\frac{(Z_s - Z_l)}{(Z_s + Z_l)}\)

\(\frac{(Z_l - Z_s)}{(Z_s + Z_l)}\)

Quiz

Year 2025

February
Week # 2 Quiz 4

Q2. A transmission line of 210 km length has certain values of A, B, C, D. If the length is made 100 km, then the parameter

Q3. A 3-phase transmission line is being supported by three disc insulators. The potentials across top unit (i.e., near to the tower) and middle unit are 8 kV and 12 kV respectively. Calculate the ratio of capacitance between pin and earth to the self-capacitance of each unit.

Q4. A lightning stroke current of 10 kA strikes a line of 400 \(\Omega\) surge impedance. What is the over voltage caused when a direct stroke occurs over the top of an unshielded transmission line?

Q5. A string type insulator has \(4\) units with self capacitance \(C\) and shunt capacitance of \(0.3 \times C\). Find the string efficiency.

Q6. A shunt capacitor at 100 MVAr is operated at 105% of its rated voltage and at 98% of its rated frequency. The reactive power produced by the capacitor is

Q7. If the inductance and capacitance of a system are 1 H and 0.01 μF respectively and the instantaneous value of the current interrupted is 10 A, the value of the shunt resistance across the breaker for critical damping is

Q8. Determine the ohmic value of the current limiting reactor per phase external to a 30 MVA, 11 kV, 50 Hz, three phase synchronous generator which can limit the current on short circuit of 5 times the full load current. The reactance of the synchronous generator is 0.05 pu.

Q9. The parameters of a transposed overhead transmission line are given as: self reactance \(X_S=0.4\) ohm/km and mutual reactance \(X_m = 0.1\) ohm/km. The positive and zero sequence reactance respectively, in ohm/km are

Q10. Reflection coefficient of current \(R_I\) is, (\(Z_l =\) Surge impedance of load, \(Z_s =\) Surge impedance of line)

Quiz

Year 2025

February Week # 1 Expire on 28 Feb 2025

February Week # 2 Expire on 07 Mar 2025

February Week # 3 Expire on 14 Mar 2025

February Week # 4 Expire on 21 Mar 2025

February Week # 2 Quiz 4

Q2. A transmission line of 210 km length has certain values of A, B, C, D. If the length is made 100 km, then the parameter

Q3. A 3-phase transmission line is being supported by three disc insulators. The potentials across top unit (i.e., near to the tower) and middle unit are 8 kV and 12 kV respectively. Calculate the ratio of capacitance between pin and earth to the self-capacitance of each unit.

Q4. A lightning stroke current of 10 kA strikes a line of 400 \(\Omega\) surge impedance. What is the over voltage caused when a direct stroke occurs over the top of an unshielded transmission line?

Q5. A string type insulator has \(4\) units with self capacitance \(C\) and shunt capacitance of \(0.3 \times C\). Find the string efficiency.

Q6. A shunt capacitor at 100 MVAr is operated at 105% of its rated voltage and at 98% of its rated frequency. The reactive power produced by the capacitor is

Q7. If the inductance and capacitance of a system are 1 H and 0.01 μF respectively and the instantaneous value of the current interrupted is 10 A, the value of the shunt resistance across the breaker for critical damping is

Q8. Determine the ohmic value of the current limiting reactor per phase external to a 30 MVA, 11 kV, 50 Hz, three phase synchronous generator which can limit the current on short circuit of 5 times the full load current. The reactance of the synchronous generator is 0.05 pu.

Q9. The parameters of a transposed overhead transmission line are given as: self reactance \(X_S=0.4\) ohm/km and mutual reactance \(X_m = 0.1\) ohm/km. The positive and zero sequence reactance respectively, in ohm/km are

Q10. Reflection coefficient of current \(R_I\) is, (\(Z_l =\) Surge impedance of load, \(Z_s =\) Surge impedance of line)

Record & Track Your Performance

February
Week # 2 Quiz 4