All Free Electrical Engineering MCQs with Answers
Every Electrical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
3,143 questions · page 81 of 158
- A. steel tape
- B. galvanised steel wire
- C. any of the above
- D. none of the above
Explanation: Cable armour is commonly made from steel tape or galvanised steel wire, depending on the cable construction and required mechanical…
Correct answer: any of the above- A. unsheathed cables
- B. armoured
- C. PVC sheathed cables
- D. all of the above
Explanation: Conduits provide mechanical protection and enclosure for unsheathed wires or cables, which otherwise lack a protective outer sheath.
Correct answer: unsheathed cables- A. polyvinyl chloride
- B. post varnish conductor
- C. pressed and varnished cloth
- D. positive voltage conductor
- E. none of the above
Explanation: PVC is the standard abbreviation for polyvinyl chloride, a thermoplastic widely used as cable insulation and sheathing because it is…
Correct answer: polyvinyl chloride- A. composite
- B. porous
- C. homogeneous
- D. hygroscopic
Explanation: Capacitance grading uses layers of different permittivities arranged so the electric stress is distributed more uniformly across the…
Correct answer: composite- A. 5 ohms
- B. 20 ohms
- C. 50 ohms
- D. 100 ohms
Explanation: The surge impedance of a power cable is low compared with that of an overhead line because the cable has high capacitance and low…
Correct answer: 50 ohms- A. armour
- B. bedding
- C. conductor surface
- D. lead sheath
Explanation: For a cable, dielectric stress is greatest at the conductor surface and decreases outward, reaching its minimum at the outer conducting…
Correct answer: lead sheath- A. the resistance of the conductor
- B. the inductance of conductors
- C. the capacitances of insulated conductors
- D. all above parameters
Explanation: A cable fault changes the capacitance distribution between its insulated conductors, so comparing their capacitances helps locate the…
Correct answer: the capacitances of insulated conductors- A. oil filled
- B. S.L. type
- C. belted
- D. armoured
Explanation: For voltages above about 66 kV, oil-filled cables are commonly used because the oil improves insulation and helps remove heat.
Correct answer: oil filled- A. 200 V
- B. 500 V
- C. 700 V
- D. 1000 V
Explanation: Low-tension cable classification generally covers voltages up to 1,000 V.
Correct answer: 1000 V- A. 11kV
- B. 33kV
- C. 66 kV
- D. 132 kV
Explanation: In the conventional cable classification, high-tension cables are used up to 11 kV; higher ranges are classified as super-tension or…
Correct answer: 11kV- A. 5 kV/mm
- B. 15 kV/mm
- C. 30 kV/mm
- D. 200 kV/mm
Explanation: Rubber has a dielectric strength of approximately 30 kV/mm, meaning a 1 mm layer can withstand about 30 kV before electrical breakdown.
Correct answer: 30 kV/mm- A. insulation layer
- B. sheath
- C. armour
- D. conductor surface
Explanation: The radial electric stress in a cable is greatest at the conductor surface because stress decreases as the distance from the conductor…
Correct answer: conductor surface- A. blue
- B. black
- C. brown
- D. none of the above
Explanation: Under the modern harmonized cable colour code, the neutral conductor is identified by blue insulation.
Correct answer: blue- A. be acid proof
- B. be non-inflammable
- C. be non-hygroscopic
- D. have all above properties
Explanation: Good cable insulation should resist chemical attack, absorb little moisture, and not readily support combustion.
Correct answer: have all above properties1615. The current carrying capacity of cables in D.C. is more than that in A.C. mainly due to__________?
- A. absence of harmonics
- B. non-existence of any stability limit
- C. smaller dielectric loss
- D. absence of ripples
- E. none of the above
Explanation: A DC cable has no alternating electric field and therefore does not suffer AC dielectric loss; it also avoids AC charging-current effects.
Correct answer: smaller dielectric loss- A. hessian cloth
- B. jute
- C. any of the above
- D. none of the above
Explanation: Cable bedding is commonly made from fibrous materials such as jute or hessian cloth, placed over the metallic sheath before armouring.
Correct answer: any of the above- A. earthing connection
- B. bedding
- C. armouring
- D. none of the above
Explanation: Bedding is placed immediately over the metallic sheath to protect it from mechanical damage by the armour.
Correct answer: bedding- A. varnished cambric
- B. vulcanised rubber
- C. impregnated paper
- D. none of the above
Explanation: Empire tape is varnished cambric, a flexible insulating tape used in electrical insulation. It is not ordinary rubber or impregnated paper.
Correct answer: varnished cambric- A. Bedding
- B. Sheath
- C. Armouring
- D. None of the above
Explanation: Armouring, usually made from steel wires or strips, provides the cable with mechanical protection against impact and pulling forces.
Correct answer: Armouring- A. low cost
- B. high dielectric strength
- C. high mechanical strength
- D. all of the above
Explanation: A practical cable insulator should be economical, withstand high electric stress, and resist mechanical damage.
Correct answer: all of the above