Calculation of Crippling (Ultimate Transverse) Load on Electrical Pole

Calculation of Crippling (Ultimate Transverse) Load on Electrical Pole

  • Wind Speed = 89 Mile/Hr.
  • Height of Pole=10 Meter
  • Type of Pole =RCC
  • Height of Pole in Ground=1.5 Meter.
  • Pole Section on Bottom of Pole (Length x Width)=400mm x 150mm
  • Pole Section on Top of Pole (Length x Width)=127mm x 150mm
  • Conductor Mounting from top of Pole(g)=0.5 Meter.
  • Distance between Two Pole(s) =20 Meter.
  • No of Conductor on Pole(n)=3No’s
  • Size of Conductor(r)= 30mm

Calculations:

  • Wind Pressure = 00256 x 2x Wind Speed
  • Wind Pressure = 00256 x 2x 90 = 20.506 Pound /Sq.Foot
  • Wind Pressure(Wp) =4.882×20.506 = 100 Kgf/M2
  • Wind Load on Conductor/Span(ws)=2/3 x Wp x s x r x n
  • Wind Load on Conductor/Span(ws)=2/3 x 100 x 20 x 30 x 3 =120 Kg———–(I)
  • Height of Pole Above Ground (h)= 10-1.5 =8.5 Meter
  • Total Bending Movement at Ground Level due to Wind Load on All Conductor=ws x h
  • Total Bending Movement at Ground Level due to Wind Load on All Conductor(b)=120 x 8.5= 960 Kg.Mt
  • Equivalent Safe Working Load at said Meter from TOP of The Pole corresponding to Wind Load on All Conductors =b / (h- g) = 960 / 8.5-0.5 =120 Kg
  • Wind Load on Pole Surface above Ground Level (p1)=Wp x h /((l1+w1)/(2×1000))
  • Wind Load on Pole Surface above Ground Level (p1)=100×8.5/(400+150/2×1000) =233.75 Kg
  • Centre of Gravity of Tapering rectangular section of Pole(p2)= (h/3)x((l2+(l1*2))/(l1+l2))
  • Centre of Gravity of Tapering rectangular section of Pole(p2)= (5/3)x((127+(400×2)) /(127+400))=4.98Mt
  • Bending Movement at Ground Level due to Wind Load on Pole(p) =p1 x p2
  • Bending Movement at Ground Level due to Wind Load on Pole(p) =233.75×4.98=1164.98 Kg.Mt
  • Equivalent Safe Working Load at said meter from Top of The Pole corresponding to Wind Load on Pole(wt) = p /(h-g) =1164.98 / (8.5-0.5) = 62 Kg——————————(II)
  • Total Transverse Load at said meter from Top of The Pole (Due to wind Load on Conductors + Wind Load on Pole Surface) (T)=Ws + Wt = 120+145.62 =256.62 Kg
Type of Pole Safety Factor
Wooden Pole 3.5
RCC Pole 2.5
PCC Pole 2.5
Steel Tubular Pole 2
Rail/RSJ Pole 2
Struts (Steel Pole) 2.5
Struts (RCC/PCC) 3
PCC Pole for 33 KV 2

 

  • From Above Table Safety Factor=2.5
  • Total Transverse Load (Crippling Load) of Pole = T x Safety Factor
  • Total Transverse Load (Crippling Load) of Pole = 256 x 2.5 =664 Kg.
  • Total Transverse Load (Crippling Load) of Pole=664 Kg
Max. Length of Pole (Meter) Min. Ultimate Transverse Load from 0.6meter from Top (Kg)
17 3000
17 2300
17 2000
17 1400
16 1100
15 1050
14 1050
13 1000
12 800
11 600
10 500
9 300
8 200
7 200
6 200
5 150
4 150
3 150

 

  • From Above Table Min. Ultimate Transverse Load for 10 Meter Pole = 500 Kg and as per our calculation it is 664 Kg hence Selection of Pole if O.K

Results:

  • Calculated Transverse Load (Crippling Load) of Pole = 664 Kg

About Jignesh.Parmar (B.E,Mtech,MIE,FIE,CEng)
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE) and CEng,India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

2 Responses to Calculation of Crippling (Ultimate Transverse) Load on Electrical Pole

  1. Muhammad Mohsin Ansari says:

    Thanks

  2. ARIF ALAM says:

    Dear Sir,

    Kindly send the standard and brief calculation of cable sizing and busbar sizing as per load…

    Thanks & Regards,

    Arif Alam

    On Sun, 19 Jul 2020, 9:41 am Electrical Notes & Articles, wrote:

    > Jignesh.Parmar (B.E,Mtech,MIE,FIE,CEng) posted: “Calculation of Crippling > (Ultimate Transverse) Load on Electrical Pole Wind Speed = 89 Mile/Hr. > Height of Pole=10 Meter Type of Pole =RCC Height of Pole in Ground=1.5 > Meter. Pole Section on Bottom of Pole (Length x Width)=400mm x 150mm ” >

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