1. An 11 kV, 3-phase transmission line has a resistance of 1.5 Ω and reactance of 4 Ω per phase. The efficiency of the line when supplying the load of 4 MW at 0.8 lagging power factor is nearly
2. At what power factor will a lossless line with a reactance of 0.6 pu exhibit zero regulation given that the sending end voltage is 1.0 pu?
- 0.800 lead
- 0.800 lag
- Unity p.f.
- 0.954 lead
3. The time interval needed for a surge to travel to the end of a 600 Km long overhead transmission line is
- 6 s
- 2 s
- 20 ms
- 2 ms
4. An extra high voltage transmission line of length 300 km can be approximated by a lossless line having propagation constant β = 0.00127 rad/km. The percentage ratio of line length to wavelength will nearly be
5. Consider a transmission line. The sending end voltage and current are expressed in terms of receiving end voltage and current for the network as
Vs = AVR + BIR
Is = CVR+ DIR
where A, B, C and D are generalized circuit constants.
The condition for symmetry for the network is
6. Which of the following is the demerit of a ‘constant voltage transmission system’?
- Increase of short-circuit current of the system
- Availability of steady voltage at all loads at the line terminals
- Possibility of better protection for the line due to possible use of higher terminal reactances
- Improvement of power factor at times of moderate and heavy loads
- Possibility of carrying increased power for a given conductor size in case of long-distance heavy power transmission
7. The square root of the ratio of line impedance and shunt admittance is called the
- surge impedance of the line
- the conductance of the line
- regulation of the line
- none of the above
8. The phenomenon of rising in voltage at the receiving end of the open-circuited or lightly loaded line is called the
- Seeback effect
- Ferranti effect
- Raman effect
- None of the above
9. 310 km line is considered as
- a long line
- a medium line
- a short line
- any of the above
10. Which of the following are the constants of the transmission lines?
- All of the above