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Blow Off Calculation Rev.1

The document provides calculations for wind load on overhead contact lines for different span lengths between 27m to 54m. It calculates the blow off, which is the maximum lateral displacement of pantograph due to wind load, for different spans based on factors like wind pressure, diameter and weight of contact wire and catenary wire, span length, tension in wires, etc. The blow off values range from 84.09mm to 336.38mm for different spans. It also states that the acceptable sway of pantograph is 525mm which is more than the calculated blow off values, making the design safe.

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Ankit Agarwal
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665 views4 pages

Blow Off Calculation Rev.1

The document provides calculations for wind load on overhead contact lines for different span lengths between 27m to 54m. It calculates the blow off, which is the maximum lateral displacement of pantograph due to wind load, for different spans based on factors like wind pressure, diameter and weight of contact wire and catenary wire, span length, tension in wires, etc. The blow off values range from 84.09mm to 336.38mm for different spans. It also states that the acceptable sway of pantograph is 525mm which is more than the calculated blow off values, making the design safe.

Uploaded by

Ankit Agarwal
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLSX, PDF, TXT or read online on Scribd
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stagger S1 300 250

stagger S2 300 250

Track Gauge 1435


Ambient temp 0 to 65
Half working width of pantograph, mm 525

Blow off = 1.05*(Wp+Wq)*L*L/(8*(T1+T2)

Span Radious In Static


Versine Sway of
length curvature offset Blow off (mm)
(mm) Pantograph
(m) (mm) (mm)

1 2 3 4 5 6

L 112.5 kg/mm2 154 mm

16 125 400 -150 29.531 183.53


18 125 350 -50 37.375 191.38
22.5 200 320 -20 58.399 212.40
27 400 370 -70 84.095 238.09
31.5 600 370 -70 114.462 268.46
36 650 200 100 149.502 303.50
40.5 750 120 180 189.213 343.21
45 700 300 0 233.597 387.60
49.5 1200 300 0 282.652 436.65
54 1400 200 100 336.379 490.38

Acceptable Value 525 mm


Hence safe.
Wind Perssure Adopted 112.5 kg/m2
Contact wire dia 14.5
Catenary wire dia 10.5
Drag factor changed to 1 (from 2/3) as
Drag Factor 0.75 per EN 50119,
drag factor 0.75 considered
Contact wire (Wp), kg/m 1223.438
Catenary (Wq), kg/m 885.938
Tension Catenary, T1 1200
Tension Contact wire, T2 1200

Sway of the Panto graph due to


vehicle and panto graph
dynamics is max 154
mm (Rolling Stock data)
Item No. 1.11

Wind Load Calculation


Wind Pressure Kg/m2 112.5 112.5

N/m2
Wind Pressure, qK OR 1103.248 1103.248
Pa
OR
Kg/m
Drag Factor of the conductor, C c - 0.75 0.75
Contact Wire Diameter, d m 0.0145 0.0145
Catenary Diameter, d m 0.0105 0.0105
Structural repsonce factor for conductors, G c 0.75 0.75
L1, L2 - Length of two adjacent spans 54 49.5
ɸ - is the angle of incidence of the critical wind
direction in respect to the perpendicular to the cos2ɸ 1 1
conductor. In general ɸ is assumed to be zero.
Wind load on Contact wire N 485.91 445.42
Wind load on Catenary wire N 351.87 322.54
Contact wire (Wp) kg/m 1.223 1.223
Catenary (Wq) kg/m 0.886 0.886
Tension catenary kgf 1200 1200
Tension contact wire kgf 1200 1200
Blow off 1.05*(Wp+Wq)*L*L/(8*(T1+T2) m 0.33637939453 0.28265213
Blow off in mm 336.38 282.65
Sway at Design Speed 154 154
Half Width 525 525
Total Blow Off 490.38 436.65

As per EN 50119, 2009


Wind Load = Wind presseure qK x Gc x d x Cc x (L1+L2)/2) x Cos2 ɸ
112.5 112.5 112.5 112.5 112.5

1103.248 1103.248 1103.248 1103.248 1103.248

0.75 0.75 0.75 0.75 0.75


0.0145 0.0145 0.0145 0.0145 0.0145
0.0105 0.0105 0.0105 0.0105 0.0105
0.75 0.75 0.75 0.75 0.75
45 40.5 36 31.5 27

1 1 1 1 1

404.93 364.43 323.94 283.45 242.96


293.22 263.90 234.58 205.26 175.93
1.223 1.223 1.223 1.223 1.223
0.886 0.886 0.886 0.886 0.886
1200 1200 1200 1200 1200
1200 1200 1200 1200 1200
0.2335968 0.18921341 0.14950195 0.11446243 0.0840948
233.60 189.21 149.50 114.46 84.09
154 154 154 154 154
525 525 525 525 525
387.60 343.21 303.50 268.46 238.09

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