MCQOPTIONS
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MCQOPTIONS
This section includes 121 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
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. | ne half |
| B. | ouble |
| C. | our times |
| D. | one of the above |
| Answer» B. ouble | |
| 2. |
A cable carrying alternating current has |
| A. | ysteresis losses only |
| B. | ysteresis and leakage losses only |
| C. | ysteresis, leakage and copper losses only |
| D. | ysteresis, leakage, copper and friction losses |
| Answer» C. ysteresis, leakage and copper losses only | |
| 3. |
In case of three core flexible cable the color of the neutral is |
| A. | Blue |
| B. | Black |
| C. | Brown |
| D. | None of the above |
| Answer» B. Black | |
| 4. |
Copper as conductor for cables is used as |
| A. | Annealed |
| B. | Hardened and tempered |
| C. | Hard drawn |
| D. | Alloy with chromium |
| Answer» B. Hardened and tempered | |
| 5. |
The thickness of metallic shielding on cables is usually |
| A. | 0.04 mm |
| B. | 0.2 to 0.4 mm |
| C. | 3 to 5 mm |
| D. | 40 to 60 mm |
| Answer» D. 40 to 60 mm | |
| 6. |
The advantage of oil filled cables is |
| A. | More perfect impregnation |
| B. | Smaller overall size |
| C. | No ionization, oxidation and formation of voids |
| D. | All of the above |
| Answer» E. | |
| 7. |
Rubber is most commonly used insulation in cables. |
| A. | Yes |
| B. | No |
| Answer» B. No | |
| 8. |
The electrostatic stress in underground cables is |
| A. | Same at the conductor and the sheath |
| B. | Minimum at the conductor and maximum at the sheath |
| C. | Maximum at the conductor and minimum at the sheath |
| D. | Zero at the conductor as well as on the sheath |
| Answer» D. Zero at the conductor as well as on the sheath | |
| 9. |
Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ? |
| A. | Polyvinyle chloride |
| B. | Vulcanised rubber |
| C. | Impregnated paper |
| D. | Compressed SFe gas |
| E. | none of the above |
| Answer» E. none of the above | |
| 10. |
It is difficult to maintain oil filled cables. |
| A. | Yes |
| B. | No |
| Answer» B. No | |
| 11. |
Which of the following insulation is used in cables? |
| A. | Varnished cambric |
| B. | Rubber |
| C. | Paper |
| D. | Any of the above |
| Answer» E. | |
| 12. |
The current carrying capacity of cables in D.C. is more than that in A.C. mainly due to |
| A. | Absence of harmonics |
| B. | Nonexistence of any stability limit |
| C. | Smaller dielectric loss |
| D. | Absence of ripples |
| Answer» D. Absence of ripples | |
| 13. |
The insulating material should have |
| A. | Low permittivity |
| B. | High resistivity |
| C. | High dielectric strength |
| D. | All of the above |
| Answer» E. | |
| 14. |
The metallic sheath may be made of lead or lead alloy or of aluminum. |
| A. | Yes |
| B. | No |
| Answer» C. | |
| 15. |
Cables for 220 kV lines are invariably |
| A. | Mica insulated |
| B. | Paper insulated |
| C. | Compressed oil or compressed gas insulated |
| D. | Rubber insulated |
| Answer» D. Rubber insulated | |
| 16. |
If the length of a cable is doubled, its capacitance |
| A. | Becomes one-fourth |
| B. | Becomes one-half |
| C. | Becomes double |
| D. | Remains unchanged |
| Answer» D. Remains unchanged | |
| 17. |
If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be |
| A. | 5 kV/mm |
| B. | 10 kV/mm |
| C. | 15 kV/mm |
| D. | 30 kV/mm |
| Answer» C. 15 kV/mm | |
| 18. |
High tension cables are generally used up to |
| A. | 11 kV |
| B. | 33 kV |
| C. | 66 kV |
| D. | 132 kV |
| Answer» B. 33 kV | |
| 19. |
The breakdown voltage of a cable depends on |
| A. | Presence of moisture |
| B. | Working temperature |
| C. | Time of application of the voltage |
| D. | All of the above |
| Answer» E. | |
| 20. |
The minimum dielectric stress in a cable is at |
| A. | Armour |
| B. | Bedding |
| C. | Conductor surface |
| D. | Lead sheath |
| Answer» E. | |
| 21. |
In congested areas where excavation is expensive and inconvenient 'draw in system' of laying of underground cables is often adopted. |
| A. | Yes |
| B. | No |
| Answer» B. No | |
| 22. |
Capacitance grading of cable implies |
| A. | Use of dielectrics of different permeabilities |
| B. | Grading according to capacitance of cables per km length |
| C. | Cables using single dielectric in different concentrations |
| D. | Capacitance required to be introduced at different lengths to counter the effect of inductance |
| Answer» B. Grading according to capacitance of cables per km length | |
| 23. |
In a cable, the maximum stress under operating conditions is at |
| A. | Insulation layer |
| B. | Sheath |
| C. | Armour |
| D. | Conductor surface |
| Answer» E. | |
| 24. |
The breakdown of insulation of the cable can be avoided economically by the use of |
| A. | Inter-sheaths |
| B. | Insulating materials with different dielectric constants |
| C. | Both (A) and (B) |
| D. | None of the above |
| Answer» D. None of the above | |
| 25. |
Low tension cables are generally used up to |
| A. | 200 V |
| B. | 500 V |
| C. | 700 V |
| D. | 1000 V |
| Answer» E. | |
| 26. |
If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be |
| A. | 2 cm |
| B. | 10 cm |
| C. | 50 cm |
| D. | 400 cm |
| Answer» D. 400 cm | |
| 27. |
Empire tape is |
| A. | Varnished cambric |
| B. | Vulcanized rubber |
| C. | Impregnated paper |
| D. | None of the above |
| Answer» B. Vulcanized rubber | |
| 28. |
_________ cables are used for 132 kV lines. |
| A. | High tension |
| B. | Super tension |
| C. | Extra high tension |
| D. | Extra super voltage |
| Answer» E. | |
| 29. |
Conduit pipes are normally used to protect ________ cables. |
| A. | Unsheathed cables |
| B. | Armoured |
| C. | PVC sheathed cables |
| D. | All of the above |
| Answer» B. Armoured | |
| 30. |
Polyethylene has very poor dielectric and ageing properties. |
| A. | Yes |
| B. | No |
| Answer» C. | |
| 31. |
The thickness of the layer of insulation on the conductor, in cables, depends upon |
| A. | Reactive power |
| B. | Power factor |
| C. | Voltage |
| D. | Current carrying capacity |
| Answer» D. Current carrying capacity | |
| 32. |
The insulation of the cable decreases with |
| A. | The increase in length of the insulation |
| B. | The decrease in the length of the insulation |
| C. | Either (A) or (B) |
| D. | None of the above |
| Answer» B. The decrease in the length of the insulation | |
| 33. |
Solid type cables are considered unreliable beyond 66 kV because |
| A. | Insulation may melt due to higher temperature |
| B. | Skin effect dominates on the conductor |
| C. | Of corona loss between conductor and sheath material |
| D. | There is a danger of breakdown of insulation due to the presence of voids |
| Answer» E. | |
| 34. |
Pressure cables are generally not used beyond |
| A. | 11 kV |
| B. | 33 kV |
| C. | 66 kV |
| D. | 132 kV |
| Answer» D. 132 kV | |
| 35. |
The insulating material for cables should |
| A. | Be acid proof |
| B. | Be non-inflammable |
| C. | Be non-hygroscopic |
| D. | Have all above properties |
| Answer» E. | |
| 36. |
In capacitance grading of cables we use a _________ dielectric. |
| A. | Composite |
| B. | Porous |
| C. | Homogeneous |
| D. | Hygroscopic |
| Answer» B. Porous | |
| 37. |
In a cable immediately above metallic sheath ________ is provided. |
| A. | Earthing connection |
| B. | Bedding |
| C. | Armouring |
| D. | None of the above |
| Answer» C. Armouring | |
| 38. |
In the cables, sheaths are used to |
| A. | Prevent the moisture from entering the cable |
| B. | Provide enough strength |
| C. | Provide proper insulation |
| D. | None of the above |
| Answer» B. Provide enough strength | |
| 39. |
The material for armouring on cable is usually |
| A. | Steel tape |
| B. | Galvanized steel wire |
| C. | Any of the above |
| D. | None of the above |
| Answer» D. None of the above | |
| 40. |
In single core cables armouring is not done to |
| A. | Avoid excessive sheath losses |
| B. | Make it flexible |
| C. | Either of the above |
| D. | None of the above |
| Answer» B. Make it flexible | |
| 41. |
In the cables, the location of fault is usually found out by comparing |
| A. | The resistance of the conductor |
| B. | The inductance of conductors |
| C. | The capacitances of insulated conductors |
| D. | All above parameters |
| Answer» D. All above parameters | |
| 42. |
The relative permittivity of rubber is |
| A. | Between 2 and 3 |
| B. | Between 5 and 6 |
| C. | Between 8 and 10 |
| D. | Between 12 and 14 |
| Answer» B. Between 5 and 6 | |
| 43. |
In cables the charging current |
| A. | Lags the voltage by 90° |
| B. | Leads the voltage by 90° |
| C. | Lags the voltage by 180° |
| D. | Leads the voltage by 180° |
| Answer» C. Lags the voltage by 180° | |
| 44. |
Which of the following protects a cable against mechanical injury? |
| A. | Bedding |
| B. | Sheath |
| C. | Armouring |
| D. | None of the above |
| Answer» D. None of the above | |
| 45. |
The disadvantage with paper as insulating material is |
| A. | It is hygroscopic |
| B. | It has high capacitance |
| C. | It is an organic material |
| D. | None of the above |
| Answer» B. It has high capacitance | |
| 46. |
In a cable the voltage stress is maximum at |
| A. | Sheath |
| B. | Insulator |
| C. | Surface of the conductor |
| D. | Core of the conductor |
| Answer» E. | |
| 47. |
The surge resistance of cable is |
| A. | 5 ohms |
| B. | 20 ohms |
| C. | 50 ohms |
| D. | 100 ohms |
| Answer» D. 100 ohms | |
| 48. |
Cables, generally used beyond 66 kV are |
| A. | Oil filled |
| B. | S.L. type |
| C. | Belted |
| D. | Armoured |
| Answer» B. S.L. type | |
| 49. |
The advantage of cables over overhead transmission lines is |
| A. | Easy maintenance |
| B. | Low cost |
| C. | Can be used in congested areas |
| D. | Can be used in high voltage circuits |
| Answer» D. Can be used in high voltage circuits | |
| 50. |
Natural rubber is obtained from milky sap of tropical trees. |
| A. | Yes |
| B. | No |
| Answer» B. No | |