Polyethylene has very poor dielectric and ageing properties

Related Mcqs:

1. Dielectric strength of rubber is around____________?

   A. 5 kV/mm
   B. 15 kV/mm
   C. 30 kV/mm
   D. 200 kV/mm

2. The minimum dielectric stress in a cable is at_____________?

   A. armour
   B. bedding
   C. conductor surface
   D. lead sheath

3. In capacitance grading of cables we use a _______ dielectric?

   A. composite
   B. porous
   C. homogeneous
   D. hygroscopic

4. 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
   A. 15 kV/mm
   D. 30 kV/mm

5. In capacitance grading a homogeneous dielectric is used

   A. Yes
   B. No

6. Which of the following protects a cable against mechanical injury___________?

   A. Bedding
   B. Sheath
   C. Armouring
   D. None of the above

7. Cables, generally used beyond 66 kV are___________?

   A. oil filled
   B. S.L. type
   C. belted
   D. armoured

8. 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

9. If the length of a cable is doubled, its capacitance____________?

   A. becomes one-fourth
   B. becomes one-half
   C. becomes double
   D. remains unchanged

10. 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