Design of the Pole

PROJECT:

Construction of 33kV Substation at NTPC Lara

CUSTOMER:

NTPC , LARA

CONTRACTOR 

C & ELECTRIC LTD

Client PO PROJECT:

Construction Power Package NTPC, Lara

Consultant:

DR N.

NAME

 M/s. Alif Engineers & Planners, Mumbai

PRPD CHKD APPD

A.K. S.A S.A

SIGN

DATE 25.06.13 25.06.13 25.06.13

TITLE

11KV POLE - DESIGN CALCULATIONS

DOC. NO. C&S/LARA/AEP/C/101

REV. NO. 0

DESIGN OF THE FOUNDATION FOR THE POLE

INPUT

DETAILS OF POLE HT h1 2.7 h2 2.7 5.6 h3 11 m Tot Ht

DIA OF POLE 140 163 194

Self wt of the Pole

=

241 kg

Minium depth of embedment Prvide Pedestal of size

=

=

1/6 x

0.7 x

0.7 x

11 =

1.83 m

1.95

(150mm above ground)

1.0 WIND LOAD CALCULATION

Calculation of design wind pressure

(As per IS:802 )

Basic wind speed

Vb =

Reference Wind Speed V R

44 =

Risk Co-efficient Terrain category

Vb/Ko

k1 = (category-1 and class-A) k2 = Vd = Vb * k1 * k2 = 34.24

Design wind Speed Design Wind Pressure

Pd

=

0.6

m/s

Wind Zone

=

44

1.07

/

1.375

= =

1

(Category -1)

m/s

2 Vz 2

703

=

=

N/m

70.34

Overturning Moment due to the wind on the pole : M

=

70.34 x 70.34 x 70.34 x

( ( (

 =

410.1 kg.mtr

2.7 x 2.7 x 5.6 x

0.1 ) 0.2 ) 0.2 )

Total weight of pole + foundation = Stabilizing Moment =

Factor of Safety

=

2630 x

2.24

>

0.35 =

32.00 m/s

(Reliability level -1 )

x x x

9.7 x 7 x 2.8 x

0.6 + 0.6 + 0.6 +

241 +

0.7 x

0.7 x

920.4125 Kgm

2 Hence safe

Provide a block of 0.7 x 0.7 x 1.95 m for all pole foundation in 1:3:6 grade Concrete All foundations shall be minm 500mm below natural grund level.

1.95 x

2500 =

2629.75 Kg

kg/m

2

3