Question
Download Solution PDFThe maximum and minimum stress in the dielectric of a single core cable are 80 kV/cm (rms) and 20 kV/cm (rms), respectively. If the conductor diameter is 4 cm, then find the thickness of insulation.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe correct answer is option 2):(6 cm)
Concept:
Maximum dielectric stress (at the surface of the conductor) is given by
Minimum dielectric stress (at the inner sheath) is given by
Condition for minimizing dielectric stress (economical)
The ratio between the maximum and minimum stress in the dielectric of a single-core cable is given as
Insulation thickness =
Where
g = electric field intensity
d = Diameter of the conductor
D = Diameter of the inner sheath
r = conductor radius
R = inner sheath radius
V = peak value of the potential of conductor w.r.t sheath
Calculation:
Givengmx = 80 kV/cm
gmn = 20 kV/cm
d = 4 cm
D =
=
= 16
Insulation thickness =
=
= 6 cm
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