1. The transfer of the reactive power over a line mainly depends upon _____
a) Vr
b) Vs
c) |Vs| – |Vr|
d) Power angle
Explanation: Reactive power flow depends on the |Vs|-|Vr|.
2. For a medium transmission line system if the sending end line voltage is 143 kV with the line impedance as 101.24∠74° Ω and shunt admittance of 7.38*10-4∠90° Ω-1.Then the no load line voltage at the receiving end would be _________
a) 148.3 kV
b) 140.8 kV
c) 149.2 kV
d) 132 kV
Explanation:
3. For a medium transmission line system if the sending end line voltage is 143 kV with the line impedance as 101.24∠74° Ω and shunt admittance of 7.38*10-4∠90° Ω-1 delivering 25 MVA at 0.8 power factor lagging in nature to the load at 132 kV. The voltage regulation is ___________
a) 12.3
b) 12.8
c) 14.2
d) -2.3
Explanation:
Voltage regulation = (148.3-132)/132 = 12.3%.
4. For the lines more than 250 km, the parameters of a line are considered not ______ but _____
a) lumped, distributed
b) distributed, lumped
c) lumped, non uniform lumped
d) uniform, lumped
Explanation: For long transmission lines, the parameters are considered uniformly distributed.
5. Which of the parameters of a long transmission line and medium transmission lines are same?
a) A and D
b) B, C
c) Only A
d) Only D
Explanation: A and D parameters of LTL and MTL are almost same.
6. With 100% series compensation of the transmission lines, which of the following effects are observed?
(i) Low transient voltage
(ii) High transient current
(iii) The current is series resonant at power frequency
a) (ii), (iii)
b) (i), (ii)
c) (i), (ii), (iii)
d) (iii)
Explanation: 100% compensation of the line results in high transient current at power frequency.
7. With 100% series compensation of the transmission lines, which of the following effects are not observed?
(i) Low transient voltage
(ii) High transient current
(iii) The current is series resonant at power frequency
a) (ii), (iii)
b) (i)
c) (i), (ii), (iii)
d) (iii)
Explanation: 100% compensation of the line results in high transient current at power frequency
8. Surge impedance for 400ohms implies for a transmission line that ___________
a) line can be theoretically loaded up to 400ohms
b) line can be practically loaded up to 400ohms
c) open circuit impedance of 400ohms
d) short circuit impedance of 400ohms
Explanation: Surge impedance decides the maximum value for a transmission line loading.
9. The larger power can be transmitted over a line with fixed voltage profile when ______
a) compensators are installed
b) negative VAR is fed
c) positive VAR is fed
d) compensators are installed and postive VAR is fed
Explanation: Compensators allow the flow of a large power through the TL by feeding positive VAR into the system.
10. A rectangular voltage wave is impressed on a long overhead line, with the far end of the line being open circuited. After reaching line end, the current is _________
a) current is reflected back with positive but voltage with negative sign
b) current is reflected back with negative but voltage with positive sign
c) both current and voltage are reflected with negative sign
d) both current and voltage are reflected with positive sign
Explanation: For open circuited end, ρ(v) = 1; ρ(i) = -1.