Download 1.When a line-to-ground fault occurs, the current in a faulted phase

1.When a line-to-ground fault occurs, the current in a faulted phase is 100A. The current in other two
phases will be
zero
33.3A
66.6A
100A
Ans:a
2.In which fault zero sequence network is not connected
line to ground
line to line
ground to neutral
double line to ground
Ans:b
3.Symmetrical Fault analysis includes
three Phase Fault
L-G fault
LL-Fault
LLG-Fault
Ans:a
4.Operator ‘a’ gives
Phase difference 120º
Phase difference 240º
Phase difference 360º
none
Ans:a
5.Zero Sequence Impedance for transmission line is __________ than positive and Negative sequence
Impedance
greater
lesser
equal
none
Ans:a
6.UnSymmetrical Fault analysis not includes
three Phase Fault
L-G fault
LL-Fault
LLG-Fault
Ans:a
7.For a large power system network short circuit study involves
Voltage
Z bus
Y bus
current
Ans:b
8.Positive sequence component has
equal magnitude
opposite magnitude
opposite phase sequence
none
Ans:a
9.Which sequence contains active sources
Positive
Negative
Zero
zero and positive
Ans:a
10.The zero sequence reactance of lines is about
5 times
2 to 3 times
>5 times
1 to 2 times
Ans:b
::The voltage source is un available in
{
~positive sequence
=negative sequence
~zero &positive
~Reactance diagram
}
::Digital fault studies are carried out using
{
=Zbus
~Ybus
~reactance bus
~all of thes
}
::The number of elements added at one time in formulating Zbus is
{
~0
=1
~2
~3
}
::Which sequence contains active sources
{
~0
~negative
~symmetrical
=positive
}
::Major Cause of symmetrical fault includes
{
~Wind and ice loading on the lines
=Insulation failure of the system
~Overloading of underground cables
~all of these
}
::The main assumption to be considered for Short circuit analysis
{
~post fault current is zero
=pre fault current is zero
~pre fault current is high
~post fault current is high
}
::Determination of SCC involves
{
=Thevenins impedance
~Nortons impedance
~series impedance
~parallel impedance
}
::Transient reactance involves
{
~the reactance value before fault
=the reactance value during fault
~the reactance value after clearing fault
~none of these
}
::steady state reactance involves
{
~the reactance value before fault
~the reactance value during fault
=the reactance value after clearing fault
~none of these
}
::Sub Transient reactance involves
{
~the reactance value before fault
=the reactance value immediately after the occurence of fault
~the reactance value after clearing fault
~none of these
}
::For a large system Computation of short circuuit studies is done using
{
=Zbus
~Ybus
~reactance bus
~all of these
}
::Unsymmetrical fault analysis can be made possible by
{
~positve sequence
~Negative sequence
~zero sequence
=symmetrical component transformation
}
::Positive sequence component involves________________compared to original phasor
{
~equal magnitude and opposite phase sequence
=equal magnitude and equal phase sequence
~equal magnitude and no phase sequence
~zero magnitude and no phase sequence
}
::Negative sequence component involves________________compared to original phasor
{
=equal magnitude and opposite phase sequence
~equal magnitude and equal phase sequence
~equal magnitude and no phase sequence
~zero magnitude and no phase sequence
}
::Zero sequence component involves________________compared to original phasor
{
~equal magnitude and opposite phase sequence
~equal magnitude and equal phase sequence
=equal magnitude and no phase sequence
~zero magnitude and no phase sequence
}
::An'a'operator has
{
=magnitude 1 and angle 120
~magnitude 1 and angle 240
~magnitude 1 and angle 360
~magnitude 0 and angle 120
}
::'a2' has
{
~magnitude 1 and angle 120
=magnitude 1 and angle 240
~magnitude 1 and angle 360
~magnitude 0 and angle 120
}
::'a3' has magnitude
{
~ 1 and angle 120
=1
~magnitude 1 and angle 240
~magnitude 0 and angle 120
}
:: The property with 'a' operator is
{
~1+a=0
~1+a2=0
=1+a+a2=0
~1+a3=0
}
::The phase sequence voltage is given by sum of
{
~ + and _ ve sequence voltage
~ zero and _ ve sequence voltage
= +, zero and _ ve sequence voltage
~ + and zero sequence voltage
}
::Relation between phase sequence and sequence component voltages is
{
~ V012=A Vabc
=V012=Inverse A * Vabc
~Vabc=Inverse A * V012
~none of these
}
::Complex power interms of symmetricalcomponents
{
~sum of powers of phasesequence
~sum of powers of symmetrical component refers to single phase
=3*sum of powers of symmetrical component refers to single phase
~3*sum of powers of phasesequence
}
::Positive Seqence Network of transformer depends on
{
~the Connection on primary and secondary
~the source voltage and reactance
=recatance alone
~none of these
}
::Negative Seqence Network of transformer depends on
{
~the Connection on primary and secondary
~the source voltage and reactance
=recatance alone
~none of these
}
::zero Seqence Network of transformer depends on
{
=the Connection on primary and secondary
~the source voltage and reactance
~recatance alone
~none of these
}
::Positive Seqence Network of synchronous machine depends on
{
~the Connection on primary and secondary
=the source voltage and reactance
~recatance alone
~none of these
}
::Negative Seqence Network of synchronous machine depends on
{
~the Connection on primary and secondary
~the source voltage and reactance
=recatance alone
~none of these
}
::zero Seqence Network of synchronous machine depends on
{
~the Connection on primary and secondary
~the source voltage and reactance
=recatance alone
~none of these
}
::Sequence network for LG fault is given by
{
~parallel connection of +, zero and _ ve sequence network
=series connection of +, zero and _ ve sequence network
~parallel connection of + and _ ve sequence network
~none of these
}
::Sequence network for LLG fault is given by
{
=parallel connection of +, zero and _ ve sequence network
~series connection of +, zero and _ ve sequence network
~parallel connection of + and _ ve sequence network
~none of these
}