Questions
3
The current carrying capacity of cables in D.C. is more thanthat in A.C. mainly due to
Answer: smaller dielectric loss
5
In single core cables armouring is not done to
Answer: avoid excessive sheath losses
7
Underground cables are laid at sufficient depth
Answer: to minimise the effect of shocks and vibrations due to gassing vehicles, etc
8
Cables for 220 kV lines are invariably
Answer: compressed oil or compressed gas insulated
9
Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ?
Answer: Compressed SFe gas
11
The disadvantage with paper as insulating material is
Answer: it is hygroscopic
13
Capacitance grading of cable implies
Answer: use of dielectrics of different permeabilities
14
The advantage of cables over overhead transmission lines is
Answer: can be used in congested areas
15
A cable carrying alternating current has
Answer: hysteresis and leakage losses only
16
The electrostatic stress in underground cables is
Answer: maximum at the conductor and minimum at the sheath
17
In the cables, sheaths are used to
Answer: prevent the moisture from entering the cable
18
The intersheaths in the cables are used to
Answer: provide proper stress distribution
19
The insulation of the cable decreases with
Answer: the increase in length of the insulation
20
If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be
Answer: 10 kV/mm
