Supports of overhead line
- 1. Supports Of Overhead Line Submitted by:- Shreyansha Tai Sonwane
- 2. Index 1) Introduction 2) Line Poles 3) Tower 4) Cross Arms 5) Stay Set 6) Insulators 7) Conductors
- 3. Introduction What is an Overhead Line ? An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy along large
- 4. Poles Poles are classified on the basis of material used in making poles Wooden poles Concrete poles a) Reinforced cement concrete poles (RCC) b) Prestressed cement concrete poles (PCC) Steel poles a) Tubular poles b) Rail poles c) RS joist poles d) H beam poles
- 6. Steel Poles Cross Section of Rail Pole Tubular Pole Rail pole
- 7. RS Joist H Beam Cross section of RS joist Cross section of H beam
- 8. Towers Based on numbers of circuits carried by a transmission tower, it can be classified as Single circuit tower Double circuit tower Multi circuit tower. Single circuit tower
- 9. Double circuit tower Multi circuit tower
- 10. According to the angle of deviation there are four types of transmission tower A – type tower – angle of deviation 0o to 2o B – type tower – angle of deviation 2o to 15o C – type tower – angle of deviation 15o to 30o D – type tower – angle of deviation 30o to 60o As per the force applied by the conductor on the cross arms, the transmission towers can be categorized in another way Tangent suspension tower and it is generally A - type tower Angle tower or tension tower or sometime it is called section tower All B, C and D types of transmission towers come under this category.
- 11. Angle Tower Tangent Tower
- 12. Cross Arms V shaped cross arm Straight cross arm The purpose of cross arms is • to provide required space between the conductors • to provide base for mounting insulators
- 13. Stay Set The purpose to use stay set in distribution line is To balance the forces of line in different direction. The main components of stay set are • Anchor rod • CI anchor plate • Stay bow • Thimbles • Stay wire • Stay clamp • Turn buckle
- 15. Insulators 1) Insulators are mounted on the cross arms. 2) The purpose of using insulator is to Provide insulation between live part & earth part. Provide support to the conductor.
- 16. Properties of overhead line insulator High mechanical strength High relative permittivity High insulation resistance Ability to withstand large temperature variation
- 17. Types of insulators Pin type insulator Shackle insulator
- 18. Suspension type insulator Strain type insulator
- 19. Conductors The purpose of using Conductor is to Transmit the electricity from generation plants to our houses Properties of a good conductor (i) High electrical conductivity. (ii) High tensile strength in order to withstand mechanical stresses. (iii) Low cost so that it can be used for long distances. (iv) Low specific gravity so that weight per unit volume is small.
- 20. Aluminium conductor steel reinforced (ACSR) Cross section of 3 layered ACSR •Steel strands •Aluminium strands •It consists of a pore of galvanized steel strand surrounded by a no. of aluminium strands. •The steel pole takes a greater percentage of mechanical stress while the aluminium carries the bulk current. •ACSR conductor being of high tensile strength & lighter in weight produces small sag & therefore can be used for longer spans.
- 21. All Aluminum Alloy Conductors (AAAC) • In AAAC conductors central strands are made out of high strength Aluminum-Magnesium- Silicon alloy. • These conductors are designed to get better strength to weight ratio and offers improved electrical characteristics, • It has excellent sag-tension characteristics and superior corrosion resistance when compared with ACSR.