transmission TOWER PPT

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 D.Rakesh Reddy 12B81A0133

CONTENTS INTRODUCTION PARTS OF TRANSMISSION TOWER TYPES OF TRANSMISSION TOWER TOWER HEIGHT ROLE OF WIND PRESSURE PROBLEM DEFINITION TOWER HEIGHT CALCULATIONS WIND LOAD LOAD CASES ON TOWER STAAD MODELLING CONCLUSION

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 .

PARTS OF TRANSMISSION TOWER • • • • •

Peak of transmission tower Cross arm of transmission tower Cage of transmission tower Transmission tower body Insulator string

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.

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

ROLE OF WIND PRESSURE • Wind zones and basic wind speed • Variation of wind speed with height • Wind force on structure

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

• Basic Wind Speed: 44 m/s • Basic Wind Pressure: 614 N/ �2 • 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

• • • • • • • • • • •

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

• 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

• 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

/

• Modulus of Elasticity: 193.61 GN/ • Coefficient of linear expansion: 11.50 X • Maximum temperature of Earth Wire: 53

/

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 shield angle = 30 i.e., the angle between the vertical

at the peak point to the line joining the peak point and top insulator string. Tan 30 = h4 = 7.794m.

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) = 7.46KN

• 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

LOAD CASES ON TOWER 1. Normal condition @32

& 100% wind

2. GW + TC + MC + BC Broken @ 32

& 100% wind

3. GW + TC + BC + MC Broken @ 32

&100% wind

4. GW + BC + MC + TC Broken @ 32

& 100% wind

5. TC + MC + BC + GW Broken @ 32

&100% wind

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/

Section chosen = hot rolled section • Design is done according to the loading conditions and then the results are obtained.

 

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2

3

4

Axial Force Distribution Diagrams For 5 Load Cases

5

1

2

3

4

Deflected Shape Diagrams For 5 load Cases

5

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.

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