Power Systems Multiple Choice Questions on “Inductance of a Single-Phase Two-Wire Line – 1”.
1. Effect of earth is considered insignificant while calculating the inductance of a single phase transmission line.
A. True
B. False
Answer: A
Clarification: The earth’s magnetic symmetry does not affect the inductance of the line.
2. Effect of earth’s presence on the magnetic field geometry is _________________
A. significant
B. insignificant
C. cannot be said
D. none of the mentioned
Answer: A
Clarification: This is because the relative permeability of earth is about the same as that of air and its electrical conductivity is relatively small.
3. The inductance of the transmission line is do not contain effect of earth electric field geometry while the capacitances contain.
A. True
B. False
Answer: A
Clarification: It is true as the earth’s magnetic field symmetry is insignificant to the inductance while the electric field symmetry is.
4. The end effect information is included in the inductance of a transmission line.
A. True
B. False
Answer: B
Clarification: Since TL is infinitely long, the end effects are ignored and they are not a part of the inductance formula.
5. The number of the strands included in the stranded cables while implementing a similar cable equivalent of single strand should be ________
A. 3x2-3x+1
B. 2x2-3x+1
C. 3x2-2x+1
D. 3x2-x+1
Answer: A
Clarification: It is 3x2-3x+1.
6. The overall diameter of a stranded conductor if ‘x’ is the number of layers and each layer has a diameter ‘d’ will be
A. (2x-1)d
B. (3x-1)d
C. (6x-3)d
D. (2x+1)d
Answer: A
Clarification: It is given by (2x-1)d.
7. _______ conductors are the latest trend of the extra high voltage lines.
A. Bundled
B. Parallel
C. ACSR
D. Bundled or ACSR
Answer: A
Clarification: The bundled ACSR conductors have corona free characteristics and they have good tensile strength.
8. A 10 MVA, 11 kV alternator has positive, negative and zero sequence reactance of 25%, 40%,10% respectively. The resistance that must be placed in the neutral such that zero sequence of fault current for a single phase to ground fault will not exceed the rated line current in ohms is
A. 2.66 Ω
B. 1.66 Ω
C. 12.1 Ω
D. 0.22 Ω