logging in or signing up under ground transmission line suroj Download Post to : URL : Related Presentations : Let's Connect Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 772 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: September 18, 2011 This Presentation is Public Favorites: 1 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Slide 1: UNDERGROUND ELECTRIC TRANSMISSION LINE VIDHYAPEETH INSTITUTE OF SCIENCE & TECHNOLOGY BY SUROJIT MAHATOSlide 3: INTRODUCTION: This overview contains information about electric transmission lines which are installed underground, rather than overhead on poles or towers. Underground cables have different technical requirements than overhead lines and have different environmental impacts. Due to their different physical, environmental, and construction needs, underground transmission generally costs more and may be more complicated to construct than overhead lines .Slide 4: HERE WE WILL DISCUSS : v Types of Underground Electric Transmission Cables v Ancillary Facilities v Construction and Operation Considerations v Costs v RepairsSlide 5: Types of Underground Electric Transmission Cables: The common types of underground cable construction also include : v High-pressure, fluid-filled pipe (HPFF) v High-pressure, gas-filled pipe (HPGF) v Self-contained fluid-filled (SCFF) v Solid cable, cross-linked polyethylene (XLPE)Slide 6: High-Pressure, Fluid-Filled Pipe-Type Cable: 1. HPFF or HPGF Pipe-Type Cross Section: Welded Externally Coated Steel Pipe Pressurized Gas or Fluid (usually nitrogen or synthetic oil at 200 psi Segmented Copper Conductor Paper Insulation Metallic ShieldSlide 7: 2. High-Pressure, Gas-Filled Pipe-Type Cable: 3. Self-Contained, Fluid-Filled Pipe-Type: 4. Solid Cable, Cross-Linked Polyethylen:e Self-contained cables are laid either directly onto the bottom or into trenches. In crossing bodies of water, the ordinary plastic or lead covered cable is usually protected with a wrapping of tarred jute, and armored with galvanized-steel wire.Slide 8: 5. XLPE Cables with Different Voltages: Underground XLPE cables left to right: 345 kV, 138 kV, 69 kV, and distributionSlide 9: XLPE Cable Cross-Section Cross-linked Polyethylene Insulation Segmental Copper Conductor and Shield Outer CoveringsSlide 10: Ancillary Facilities : 1.Vaults : 345 kV XLPE project – Cement vault visible with two chimneys extending up to be level with the future road surface. 138 kV XLPE project – Bottom half of pre-constructed vault positioned in trench.Slide 11: 2.Transition Structures: insulators Pole height range 60’-100’ pole heads Raiser height range 30’-40’Slide 12: 3.Pressurizing Sources: Construction of Underground Transmission Installation of an underground transmission cable generally involves the following sequence of events: 1 ) ROW clearing, 2) trenching/blasting, 3) laying and/or welding pipe, 4) duct bank and vault installation, 5) backfilling, 6) cable installation, 7) adding fluids or gas, and 8) site restoration. Many of these activities are conducted simultaneously so as to minimize the interference with street traffic.Slide 13: Figures shows a typical installation sequence in a city street.Slide 14: Examples of Trench Construction:Slide 15: Costs: Cable Repairs: V One cable repair needed per year for every 833 miles of cable. V One splice repair needed per year for every 2,439 miles of cable. V One termination repair needed per year for every 359 miles of cable A typical new 69 kV overhead single-circuit transmission line costs approximately $285,000 per mile as opposed to $1.5 million per mile for a new 69 kV underground line (without the terminals). A new 138 kV overhead line costs approximately $390,000 per mile as opposed to $2 million per mile for underground (without the terminals).Slide 16: THANK YOU You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.