The positive, negative, and zero sequence reactances of a 20-MVA, 13.2 kV synchronous generator are 0.3 pu, 0.2 pu and 0.1 pu, respectively. The generator is solidly grounded and is not loaded. A line to ground fault occurs on phase a. Neglecting all the resistances, determine the positive sequence component of the fault current.
A4,374A
B1,458A
C2,525 A
D7,576A
#82📜 EE Pre-Board March 2016📘 PowerhouseHard
The sequence components of the phase c current of a 3-phase system are as follows: \(I_{c0} = 0\), \(I_{c1} = 18.4\angle 88.4^\circ\), \(I_{c2} = 3.23\angle 48.2^\circ\). Find the phase b current in amperes.
A\(19.24\angle -218^\circ\)
B\(18\angle 42^\circ\)
C\(18\angle -42^\circ\)
D\(19.24\angle 218^\circ\)
#83📜 EE Pre-Board March 2017📘 PowerhouseMedium
In a 3-phase, 4-wire system the currents in the a, b, and c lines under an abnormal condition of loading are \(I_a = 100\angle 30^\circ\) A, \(I_b = 50\angle 300^\circ\) A and \(I_c = 30\angle 180^\circ\) A. Find the zero sequence current.
A\(18.3\angle 6.81^\circ\) A
B\(17.3\angle 3.15^\circ\) A
C\(6.71\angle 5.4^\circ\) A
D\(27.29\angle 4.69^\circ\) A
#84📜 EE Pre-Board March 2017📘 PowerhouseEasy
The per unit value of 2 ohm resistor at 100 MVA base and 10 KV base voltage is
A4 pu
B2 pu
C0.5 pu
D0.2 pu
#85📜 EE Pre-Board March 2017📘 PowerhouseEasy
For a single line to ground fault, the zero sequence current is given by j3 pu. The current carried by the neutral during the fault is
Aj1 pu
Bj3 pu
Cj9 pu
Dj6 pu
#86📜 EE Pre-Board August 2017📘 PowerhouseMedium
Given three unbalanced line currents \(I_a = 0 + j12\) A, \(I_b = 5 - j10\) A and \(I_c = -10 - j5\) A. Find the negative sequence component of \(I_c\) in amperes.
A\(2.25\angle 105.7^\circ\)
B\(2.25\angle -134.3^\circ\)
C\(2.25\angle -14.3^\circ\)
D\(3.12\angle -14.3^\circ\)
#87📜 EE Pre-Board August 2017📘 PowerhouseEasy
The per-unit reactances of a synchronous generator are \(X_d = 1.1\), \(X_d' = 0.24\) and \(X_d'' = 0.15\). The generator is operating without load at 5 percent above rated voltage when a three-phase short circuit occurs at its terminals. What is the per unit subtransient fault current?
A4.375 pu
B0.955 pu
C6.67 pu
D7.0 pu
#88📜 EE Pre-Board August 2017📘 PowerhouseEasy
In a short circuit study, the positive, negative and zero sequence impedances are 0.25 pu, 0.25 pu and 0.3 pu, respectively. The base MVA is 100. Determine the fault current for a three-phase fault at the 115 kV level.
A3,000 A
B2,008 A
C1,506 A
D502 A
#89📜 EE Pre-Board March 2018📘 PowerhouseMedium
Three unbalanced 3-phase currents are given as follows: \(I_a = 10\angle -30^\circ\) A, \(I_b = 0\), \(I_c = 10\angle -150^\circ\) A. Find the positive sequence component of \(I_a\).
A\(3.34\angle 150^\circ\) A
B\(3.34\angle -150^\circ\) A
C\(3.34\angle 30^\circ\) A
D\(3.34\angle -30^\circ\) A
#90📜 EE Pre-Board March 2018📘 PowerhouseEasy
The per unit impedance of a circuit element is 0.30. If the base kV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be
A0.3
B0.6
C0.003
D0.006
#91📜 EE Pre-Board August 2018📘 PowerhouseEasy
If 25 ohms and 125 amperes are the base impedance and base current, respectively for a given system, what is the base KVA?
A781.25
B39.1
C390.625
D76.12
#92📜 EE Pre-Board August 2018📘 PowerhouseMedium
In a 13.8 kV, 10 MVA base three-phase system, a phase to phase fault occurs. If the Thevenin’s equivalent impedance of the system is 2.63%, what is the per unit fault current?
A19.01 pu
B32.93 pu
C57.03 pu
D98.78 pu
#93📜 EE Pre-Board August 2018📘 PowerhouseEasy
The current from the neutral to the ground connection is 12 A. What is the zero sequence component in each phase?
