transmission TOWER PPT

(1)

A MINI PROJECT PRESENTATION

ON

DESIGN OF TRANSMISSION

LINE TOWER USING STAAD.PRO

under the guidance of

Mr.K.Rajendra Prasad Assistant Professor

Submitted by

G.Bhavik Kumar Goud 12B81A0105 U.Nikhil 12B81A0126

(2)

INTRODUCTION

Transmission tower is a tall structure used to support a overhead power line.They are used in high-voltage AC and DC systems, and come in a wide variety of shapes and sizes. Typical height ranges from 15 to 55 metres .

(4)

PARTS OF TRANSMISSION TOWER

• Peak of transmission tower

• Cross arm of transmission tower • Cage of transmission tower

• Transmission tower body • Insulator string

(5)

(6)

TYPES OF TRANSMISSION TOWER

 Based on Angle of deviation :

1. A-type tower-anlge of deviation 0º to 2º 2. B-type tower-anlge of deviation 2º TO 15º 3. C-type tower-anlge of deviation 15º to 30º 4. D-type tower-anlge of deviation 30º to 60º

. Based on force applied by conductor on cross arms: 1. Tangent suspension tower and it is generally A-type

tower

2. Angle tower or tension tower or section tower. All B,C,D types are of this type.

(7)

TOWER HEIGHT

1. Minimum permissible ground clearance h1 2. Maximum sag h2 3. Vertical spacing between conductors h3 4. Vertical clearance

between ground wire and top conductor h4

(8)

ROLE OF WIND PRESSURE

• Wind zones and basic wind speed • Variation of wind speed with height • Wind force on structure

(9)

PROBLEM DEFINITION

Tower location is selected at Hyderabad with following specifications.

The following parameters are assumed from

IS 802 Part 1: Sec 1 : 1995, IS 5613 Part 2:Sec 1: 1989. • Transmission line voltage : 220KV

• Angle of line deviation : 0º to 2º • Terrain type considered : plain

• Terrain Category: 2 (Normal cross country lines with few obstacles)

• Return Period: 50 years • Wind zone: 3

(10)

• Basic Wind Speed: 44 m/s

• Basic Wind Pressure: 614 N/

• Reference wind speed ��

=

32m/s • Design wind speed �� = 32m/s

• Design wind pressure = 614.4 N/

• Tower Type: Self-Supporting Tower, Suspension Type Tower, Tower Type "A"

• Tower Geometry: Square Base Tower • No. of Circuits: Double Circuit

• Bracing Pattern: X-B Bracing • Cross-Arm: Pointed

(11)

• Maximum Temperature: 46 • Minimum Temperature: 6 • Peak Type: Triangular

• Number of Ground Wires: Single • Shielding Angle: 30º

• Minimum Ground Clearance: 7 m • Maximum Height above G.L = 33 m • Width at Cross Arm level = 2 m

• Width at base: 5 m

• Vertical Spacing between Conductors = 5 m • Horizontal Spacing between Conductors: 9 m

(12)

• Base Width / Height: 1:6.6

• Wind Span = Normal span = 350 m  Conductor properties

• Voltage Level: 220 kV

• Code Name of Conductor: ASCR “ZEBRA” • No. of Conductors/Phase: ONE

• Stranding / Wire dia.: 54/4.13 Al + 7/3.53 St. • Total Sectional Area: 597

• Over all dia.: 31.77 mm

• Approx. Weight: 1998 kg/km • Min. UTS: 159.6 KN

(13)

• Modulus of Elasticity: 69GN/

• Coefficient of Linear Expansion: 19.3 X / • Maximum temperature of Conductor: 75

Earth Wire Properties

• Material of Earth Wire: Galvanized Steel • No. of earth wire: ONE

• Stranding / Wire diameter: 7 / 3.15 • Total Sectional Area: 54.55

• Over all dia.: 9.45 mm

• Approx. Weight: 428 kg/km • Min. UTS: 56 KN

(14)

• Modulus of Elasticity: 193.61 GN/

• Coefficient of linear expansion: 11.50 X / • Maximum temperature of Earth Wire: 53

(15)

TOWER HEIGHT CALCULATIONS

• Here we are taking h1 = 7.478m

• we have sag S = = = 7.522m • For 220KV line of 2 circuits, minimum vertical

spacing between conductors is 4.9m. We are taking it as 5m and h3 = 10m.

• The height can be calculated by considering the

(16)

at the peak point to the line joining the peak point and top insulator string.

Tan 30 =

(17)

WIND LOAD

For wind load on tower

�� = × �� ×��  × × • At top cross arm

�� = (614.4 ×2.975 ×0.924 ×2.26254)÷4 + (614.4 ×2.08×2.286 ×2.284)

= 7.63KN

• At middle cross arm:

𝐹𝐹𝐹 = (614.4 ×2.975 ×0.924 ×2.21254) ÷4 + ( 614.4 ×2.08×2.286 ×2.234)

(18)

• At bottom cross arm: �� = (614.4 ×3.3 ×0.6996×2.07964) ÷4 + ( 614.4 ×2.08×2.286 × 2.1552) = 7.03KN • At peak point: 𝐹𝐹𝐹 = (614.4 ×3.05 ×0.4992×2.313 ) ÷3 = 0.72KN

(19)

LOAD CASES ON TOWER

1. Normal condition @32 & 100% wind

(20)

3

. GW + TC + BC + MC Broken @ 32 &100% wind

(21)

(22)

STAAD MODELLING

• Transmission line tower is modelled using the

coordinates of different nodes and then, joining them to form members and ultimately a transmission tower. • Support are chosen to be fixed.

• Then the 5 load cases are considered.

• Sections is chosen as ISEA 60 ×60 ×6 mm. • Parameters defined as

Ultimate tensile strength = 41,000 KN/ Yield strength = 25,000 KN/

(23)

Section chosen = hot rolled section

• Design is done according to the loading conditions and then the results are obtained.

(24)

Axial Force Distribution Diagrams For 5 Load Cases

1 2 ₃

(25)

Deflected Shape Diagrams For 5 load Cases

(26)

CONCLUSION

In the present study, a 220 KV transmission line tower is designed in wind zone 3 with a basic wind speed of 44m/s. The various loads acting on the tower, Conductors and the Ground wire are calculated using the required Indian Standard Codes, and then the tower is modelled and designed using STAAD.Pro V8i . The steel sections required are obtained along with member forces and Nodal displacements.

(27)