1. The electric breakdown strength of insulating materials depends on
A Nature of applied voltage
B Imperfection of dielectric material
C Pressure, temperature and humidity
D All of these
Answer: D All of these
2. In which of the following trasnsmission lines, the value of the shunt admittance should be approximated to zero?
A A 66 kV 35 km long line
B A 132 kV 200 km long line
C A 220 kV 300 km long line
D A 400 kV 500 km long line
Answer:A A 66 kV 35 km long line
3. The inductance of a power transmission line increase with
А decrease in line length
B increase in conductor diameter.
C increase in spacing between phase conductors.
D increase in load current carried by conductors
Answer :C increase in spacing between phase conductors.
4. The major criteria for selection of size of distributor for a radial distribution system is
A corona loss
B temperature rise
C capital cost
D voltage drop
Answer: D voltage drop
5. The pu impedance value of an alremator corresponding to base value of 13.2 kV and 30 MVA is 0.2 pu. The pu value for the base value 13.8 kV and 50 MVA will be
A 0.306 pu
B 0.33 pu
C 0.318 pu
D 0.328 pu
Answer: A 0.306 pu
6. In power stastion, the cost of generation of power reduces when
A diversity factor alone increase
B both diversity factor and load factor increase
C load factor alone increases
D both diversity factor and load factor decrese
Answer: B both diversity factor and load factor increase
7. A single phase transmission line of impedance 0.8 supplies a resistive load 500 A at 300 V. The sending end power factor is
A 0.6 lagging
B 0.8 lagging
C 0.8 leading
D Unity.
Answer: A 0.6 lagging
8. Which type of power plants has the highest total installed capacity in India?
A Hydro electric
B Nuclear
C Thermal
D Solar
Answer: C Thermal
9. The sag of the conductors of a transmission line is 2.5 m when the span is 250 m. Now if the height of supporting tower is increased by 25%, the sag will
A increase by 25%
B decrease by 25%
C decrease by 50%
D remain unchanged
Answer: D remain unchanged
10. If a line is 100% series compensated then series resonance occurs at
A 100 Hz
B 150 Hz
C 50 Hz
D resonance does not depend on line compensation
Answer: C 50 Hz
11. Ferranti effect in a transmission system is because of
A Inductive effect of transmission line
B Capacitive effect of transmission line
C Corona
D Resistive effect of transmission line
Answer:B Capacitive effect of transmission line
12. Which of the following is not a source of reactive power?
A Generators
B Reactors
C Resistors
D Capacitors
Answer: C Resistors
13. Bundled conductors are employed to improve
A appearance of line
B mechanical stability of line
C efficiency by reducing corona loss
D current carrying capacity of line
Answer: C efficiency by reducing corona loss
14. Galloping in transmission line conductors arises generally due to
A asymmetrical layer of ice formation
B vortex phenomenon in light winds
C heavy weight of line conductors
D adoption of horizontal conductors
Answer: A asymmetrical layer of ice formation
15. The surge impedance of a 500 km long, 400 kV transmission line is 400 ohm . The SIL (Surge Impedance Loading) is
A 200MW
B 400 MW
C 1600 MW
D 2000 MW
Answer: B 400 MW
Surge impedance is independent of length of the
line.
SIL = KV*KV/Z
16. Which of the following is TRUE with respect to HVDC transmission line?
A For a short distance it is economical over HVAC
B In HVDC system, harmonics are not generated
C Use of HVDC can improve system stability
D Less and cheap terminal equipments are required in HVDC.
Answer: C Use of HVDC can improve system stability
17. Which of following are mandatory function of Central Electricity Regulatory Commission?
(I) To regulate interstate transmission of electricity
(II) Promotion of investment in electricity industry
(111) To determine tariff for interstate electricity transmission
A Only II
B I and II
C I and III
D ll and III
Answer: C I and III
18. Transmission lines connect
A generating station to a switching station/stepdown transformer station
B stepdwon transformer station to service transformer banks
C distribution transformer to consumer peremises
D service points to consumer premises
Answer: A generating station to a switching station/stepdown transformer station
19. The voltages falling under the category of extra high voltage are
A 230 kV and above
B 132 kV and above
С 66 kV and above
D 400 kV and above
Answer: D 400 kV and above
20. Large industrial consumers are supplied power at
A 400 kV
B 11 kV
C 66 kV
D 132 kV
Answer: B 11 kV
21. As per IE rules the maximum allowable variation between declared and actual voltage at consumer's premises should be
A +6%
B +8%
C +5%
D none of above
Answer: A +6%
As per IE Rule, In the case of low or medium voltage,
by more than 6%
As per IS 12640:1988, Supply variation will become
230 V + 10 % with effect from 31 December 2009.
Earlier it was 6% in the case of low or medium voltage.
22. The underground system can not be operated above
A 220 kV
B 66 kV
C 33 kV
D 11 kV
Answer: B 66 kV
23. By increasing the transmission voltage to double of its original value the same power can be dispatched keeping the line loss
A equal to original value
B half the original value
C double the original value
D one-fourth of original value
Answer: C double the original value
24. ACSR conductors have
A all counductors made of aluminium
B outer conductors made of aluminium
C inner conductors made of aluminium
D no conductors made of aluminium
Answer: B outer conductors made of aluminium
25. ACSR conductors having 70 aluminium conductors and 6 steel conductors will be specified as
A 70/6
B 25720
C 70/76
D 6/76
Answer: A 70/6
26. The minimum clearance of high voltage lines from ground across streets is
A 3 m
B 5 m
C 6 m
D 8 m
Answer: C 6 m
27. For a 66 kV transmission line the number of dics insulators used is
A 8
B 6
C 4
D 2
Answer: B 6
28. The purpose of guard ring in transmission lines is to
A reduce the earth capacitance of the lowest unit
B increase the earth capacitance of the lowest unit
C reduce the transmission line losses
D none of above
Answer: A reduce the earth capacitance of the lowest unit
29. The current drawn by the line owing to corona loss is
A Non-sinusoidal
B Sinusoidal
C dc
D square
Answer: A Non-sinusoidal
30. In a context which statement is not true?
A Corona is voltage effect
B Corona takes place on short transmission lines
C Corona is accompanied with power loss
D Corona attenuates lightning surges
Answer: B Corona takes place on short transmission lines
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