Question:-
Calculate the sag in vertical direction
Option (A)
5.73m
Option (B)
7.73 m
Option(C)
8.73m
Option(D)
9.73m
Correct Option:
(D)
Question Solution:
The radial thickness of ice 1.25 cm, d = 1.42 cm.
Area of ice section = (π/4) [(d+2r)2 - d2 ] =πr(d+r)
Weight of ice per metre run = 913.5 x (π x 1.25 (1.42 +1.25) /104 )
= ((913.5 x 10.5) / 104) = 0.96 kg/m
Dead weight of the conductor = 1.09 kg/m.
The projected area of the ice covered conductor = 1 x ((d+2r) /100) sq.m
Wind pressure Ww = 37.8 x (3.92/100) = 1.48 kf/m
Resultant pressure Wr = √[(W+Wi)2 + Ww2 ] = √[( 1.09+0.96)2 + (1.48)2]
= √ (4.2+2.19) = 2.53 kg/m
Sag under this condition = (WrL2 /8T0) T0 = fm x a
a=(π x (1.42)2/4) = 1.578 sq.cm , T0 = 1050 x 1.578 = 1655 kg
Total Sag, S = (WrL2/8T0) = (2.53 x 250 x 250 /)/(8 x 1655) = 12m
The vertical component of the sag = 12 x ((W+Wi) / Wr )= 12 x ((1.09+0.96)/2.53) = ((12 x 205)/2.53) = 9.73m
question-answer-faq-1650