MCQOPTIONS
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MCQOPTIONS
This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In High Power Lines the power is transmitted at |
| A. | High current level and low voltage |
| B. | High voltage level and low current |
| C. | Any combination |
| D. | None of these |
| Answer» C. Any combination | |
| 2. |
Bundled conductors that are used to increase line voltage in EHV lines for raising critical corona voltage depend on |
| A. | Number of conductors in the group |
| B. | Voltage gradient |
| C. | Optimum spacing |
| D. | Communication interference |
| Answer» B. Voltage gradient | |
| 3. |
In a 3 unit insulation wire, the voltage stress is 20 kV and the wire efficiency is 75% in the entire bottom most unit. What will be the total voltage across the entire wire? |
| A. | 180 kV |
| B. | 45 kV |
| C. | 90 kV |
| D. | 22.5 kV |
| Answer» C. 90 kV | |
| 4. |
________ is a protective device that discharges excess voltage surges to earth. |
| A. | Isolater |
| B. | Surge Arrester |
| C. | Relay |
| D. | Circuit Breaker |
| Answer» C. Relay | |
| 5. |
Load reduction on power system causes |
| A. | EMI |
| B. | Sag |
| C. | Swell |
| D. | Impulse |
| Answer» D. Impulse | |
| 6. |
A certain cable has an insulation of relative permittivity = 4. If the insulation is replaced by one of relative permittivity = 2, the capacitance of the cable will become |
| A. | one half |
| B. | double |
| C. | four times |
| D. | none of the above |
| Answer» B. double | |
| 7. |
In a suspension type insulator, the voltage _______. |
| A. | across the center disc is minimum |
| B. | across the centered disc is maximum |
| C. | across the top disc is minimum |
| D. | across the top disc is maximum |
| Answer» D. across the top disc is maximum | |
| 8. |
If the connected light load in a house is 3000 W and power sub-circuit load 6000 W, then what is the number of power sub-circuits required? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 1 |
| Answer» B. 3 | |
| 9. |
_______ is a material that is used to make cable sheaths. |
| A. | Aluminium |
| B. | Copper |
| C. | Lead |
| D. | Cast iron |
| Answer» D. Cast iron | |
| 10. |
Cables used for underground services from 33 kV to 60 kV are: |
| A. | extra high-tension cables |
| B. | high tension cables |
| C. | super tension cables |
| D. | extra super voltage cables |
| Answer» B. high tension cables | |
| 11. |
If the transmission voltage of a line increase, then the volume of the conductor material required: |
| A. | decreases |
| B. | increase but with huge losses in line |
| C. | increases but without huge losses in line |
| D. | does not change |
| Answer» B. increase but with huge losses in line | |
| 12. |
Bundle conductors are used to: |
| A. | Reduce the line capacitance with respect to the ground |
| B. | Reduce corona loss |
| C. | Reduce total weight of the line |
| D. | Reduce regulation |
| Answer» C. Reduce total weight of the line | |
| 13. |
A term is given to 30 km transmission line which carries power at 33 kV. What is the term? |
| A. | Short transmission line |
| B. | Long transmission line |
| C. | High power line |
| D. | Ultra high voltage line |
| Answer» B. Long transmission line | |
| 14. |
A pin type insulator is made from |
| A. | porcelain |
| B. | glass |
| C. | ceramic |
| D. | all option are correct |
| Answer» E. | |
| 15. |
Conduit elbows are usually located at: |
| A. | The tappings of the connection |
| B. | Away from walls |
| C. | Straight runs |
| D. | Sharp ends |
| Answer» E. | |
| 16. |
Among the following statements which one is true? |
| A. | AC transmission is more efficient |
| B. | DC transmission is more efficient |
| C. | both are equally efficient |
| D. | low voltage DC transmission is more efficient |
| Answer» C. both are equally efficient | |
| 17. |
Corona loss increases with: |
| A. | Decrease in conductor size and increase in supply frequency |
| B. | Increase in both conductor size and supply frequency |
| C. | Decrease in both conductor size and supply frequency |
| D. | Increase in conductor size and decrease in supply frequency |
| Answer» B. Increase in both conductor size and supply frequency | |
| 18. |
In a tap changer, the voltage at consumer terminals is kept within the prescribed limits by varying the |
| A. | Ratio of turns between primary and secondary windings |
| B. | Frequency |
| C. | Flux density in core |
| D. | Angle between magnetic axis of the primary and secondary windings |
| Answer» B. Frequency | |
| 19. |
A 115 kV transmission line having per unit impedance of j0.4 is in parallel with a 230 kv transmission line having per unit impedance of j0.6. When 400 MW total power is transferred from one grid to another, the power transferred by the 115 kv line is |
| A. | 133 MW |
| B. | 160 MW |
| C. | 200 MW |
| D. | 240 MW |
| Answer» E. | |
| 20. |
According to 1956 Indian electricity rule 77(1) for high voltage lines, the height of overhead line including service lines erected in any part of the road should not be less than _________. |
| A. | 5.975 meters |
| B. | 5.185 meters |
| C. | 6.10 meters |
| D. | 4.575 meters |
| Answer» D. 4.575 meters | |
| 21. |
Boosters are basically: |
| A. | Inductors |
| B. | Capacitors |
| C. | Transformers |
| D. | Synchronous motors |
| Answer» D. Synchronous motors | |
| 22. |
A 3 phase induction machine draws 1000 kVA at a power factor of 0.866 lag. A synchronous condenser is connected in parallel to draw an additional power of 750 kVA at a leading pf of 0.707. The power factor of the total load supplied by the mains is |
| A. | 0.95 lag |
| B. | 0.99 lead |
| C. | 0.90 lag |
| D. | 0.95 lead |
| Answer» C. 0.90 lag | |
| 23. |
If a travelling – wave travelling along a loss free overhead line does not result in any reflection after it has reached the far end, then the far end of the line is __ |
| A. | Open circuited |
| B. | Short circuited |
| C. | Terminated into a resistance equal to surge impedance of the line |
| D. | Terminated in to a capacitor |
| Answer» D. Terminated in to a capacitor | |
| 24. |
A long overhead lossless power transmission line is terminated with its characteristic impedance. While the line is in operation |
| A. | a resonance of reactive powers occurs in the line |
| B. | the line becomes purely inductive |
| C. | the line becomes purely capacitive |
| D. | there is no reflected wave on the line |
| Answer» E. | |
| 25. |
A 3 phase 4 wire system is commonly used for: |
| A. | Primary distribution |
| B. | Secondary distribution |
| C. | Primary transmission |
| D. | Secondary transmission |
| Answer» C. Primary transmission | |
| 26. |
In induction motor, low power factor is due to |
| A. | Low load |
| B. | High load |
| C. | Overload |
| D. | None of the above |
| Answer» B. High load | |
| 27. |
Low voltage cable has operating voltage up to: |
| A. | 1 kV |
| B. | 11 kV |
| C. | 22 kV |
| D. | 66 kV |
| Answer» B. 11 kV | |
| 28. |
Consider the following statements regarding corona:1. It causes radio interference.2. It attenuates lightning surges.3. It causes power loss.4. It is more prevalent in the middle conductor of a transmission line employing a flat conductor configuration.Which of the above statements are correct? |
| A. | 1, 2 and 3 only |
| B. | 1, 2 and 4 only |
| C. | 1, 2, 3 and 4 |
| D. | 3 and 4 only |
| Answer» D. 3 and 4 only | |
| 29. |
Busbars are made up of aluminium mainly because of |
| A. | low density |
| B. | low cost |
| C. | low melting point |
| D. | high resistivity |
| Answer» C. low melting point | |
| 30. |
Pin insulators are normally used up to voltage of about |
| A. | 33 kV |
| B. | 66 kV |
| C. | 100 kV |
| D. | 11 kV |
| Answer» B. 66 kV | |
| 31. |
In case of overhead lines, the sag of the conductor is: |
| A. | directly proportional to the length of the span squared |
| B. | directly proportional to the tension at the lowest point |
| C. | inversely proportional to the weight of the conductor per unit length |
| D. | directly proportional to the length of the span |
| Answer» B. directly proportional to the tension at the lowest point | |
| 32. |
Installation of high voltage bus bar in a substation requires |
| A. | Disc insulator |
| B. | Shackle insulator |
| C. | Post insulator |
| D. | Pin insulator |
| Answer» D. Pin insulator | |
| 33. |
_____ Voltage regulation is considered to be the best for transmission lines. |
| A. | 98% |
| B. | 2% |
| C. | 40% |
| D. | 100% |
| Answer» C. 40% | |
| 34. |
Corona loss does not depend on |
| A. | Atmosphere |
| B. | Conductor size |
| C. | Line voltage |
| D. | Height of the conductor |
| Answer» E. | |
| 35. |
According to Foust and Menger, the corona loss (Pc) is proportional to Where V is the actual voltage of the conductor? |
| A. | V2 |
| B. | V3 |
| C. | V |
| D. | √V |
| Answer» C. V | |
| 36. |
As per ‘Indian Electricity Act’, the HT consumer should maintain p.f. in between |
| A. | 0.6 to 0.8 |
| B. | 0.8 to 0.85 |
| C. | 0.9 to 0.99 |
| D. | Above unity |
| Answer» D. Above unity | |
| 37. |
Maximum permissible span (in metre) for wooden poles is |
| A. | 10 |
| B. | 20 |
| C. | 30 |
| D. | 75 |
| Answer» E. | |
| 38. |
A surge voltage of 10 kV travels along a cable towards its junction with overhead line. The surge impedance of the cable and the overhead line is 50 Ω and 450 Ω respectively. The surge voltage transmitted to the overhead line is |
| A. | 2 kV |
| B. | 9 kV |
| C. | 18 kV |
| D. | 20 kV |
| Answer» D. 20 kV | |
| 39. |
An overhead line with surge impedance of 400 Ω is terminated through a resistance R. A surge travelling over the line does not suffer any reflection at the junction, if the value of R is |
| A. | 200 ohms |
| B. | 2000 ohms |
| C. | 800 ohms |
| D. | None of the above |
| Answer» E. | |
| 40. |
A loss-less transmission line having characteristic impedance Z0 is terminated in a load of ZR. If the value of ZR is exactly half of Z0 then reflection coefficient ΓL is |
| A. | 1/3 |
| B. | 2/3 |
| C. | - 1/3 |
| D. | - 2/3 |
| Answer» D. - 2/3 | |
| 41. |
Find the power factor of an installation supplying the following loads:300 kW at unity power factor, 1000 kW at 0.8 lagging power factor and 1500 kW at 0.6 leading power factor. |
| A. | 0.71 leading |
| B. | 0.71 lagging |
| C. | 0.92 leading |
| D. | 0.92 lagging |
| Answer» D. 0.92 lagging | |
| 42. |
For the same voltage drop, increasing the voltage of a distributor n-times: |
| A. | reduces the cross section of the conductor by n times |
| B. | increases the x-section of the conductor by n-times |
| C. | reduces the cross section of the conductor by n2 times |
| D. | increases the volume of the conductor |
| Answer» B. increases the x-section of the conductor by n-times | |
| 43. |
In a single-phase AC system, two wires are sufficient for transmitting voltage to the load. These are: |
| A. | red and yellow |
| B. | phase and neutral |
| C. | red and blue |
| D. | positive wire and negative wire |
| Answer» C. red and blue | |
| 44. |
In distribution systems, the conductors which connect the sub-station to the distributors are called _________. |
| A. | boosters |
| B. | substation |
| C. | feeders |
| D. | service mains |
| Answer» D. service mains | |
| 45. |
Presence of ozone owing to corona ________. |
| A. | Improves the environment |
| B. | Improves power factor |
| C. | Improves regulation |
| D. | Corrodes the material |
| Answer» E. | |
| 46. |
Choose the INCORRECT statement with respect to DC transmission systems. |
| A. | It has less corona loss and reduced interference with communication circuits. |
| B. | The potential stress on the insulation is less in case of a DC system than that in case of an AC system, for the same working voltage. |
| C. | Electric power can be generated at a high DC voltage -for a DC transmission system. |
| D. | There is no skin effect in the transmission line in a DC transmission system. |
| Answer» D. There is no skin effect in the transmission line in a DC transmission system. | |
| 47. |
A 3-phase transmission line increases transmission efficiency when _________. |
| A. | Power factor decreases |
| B. | Current density increases |
| C. | Line voltage increases |
| D. | Length of the conductor increases |
| Answer» D. Length of the conductor increases | |
| 48. |
A ______ transformer is usually mounted on a pole of the plinth. |
| A. | current |
| B. | distribution |
| C. | potential |
| D. | power |
| Answer» C. potential | |
| 49. |
A shunt capacitor used for reactive power compensation is operated at 98% of its rated frequency and 95% of its rated voltage. The reactive power supplied by this capacitor (as compared to its rated capacity) is |
| A. | 7.9% lower |
| B. | 11.5% lower |
| C. | 11.5% higher |
| D. | 7.9 higher |
| Answer» C. 11.5% higher | |
| 50. |
Determine the charging current (Ic) at 50 Hz of a single-conductor EHV transmission line having voltage to ground of 500 kV and capacitance per unit length of the conductor to ground 2 nF/km. |
| A. | 0.1 π A |
| B. | π A |
| C. | 0.01 π A |
| D. | 0.001 π A |
| Answer» B. π A | |