Transmission Towers

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  • Topic: Electric power transmission, Electricity distribution, Electricity pylon
  • Pages : 17 (2511 words )
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  • Published : October 6, 2011
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TRANSMISSION TOWER
R.Saravanan, PGET, L&T, UAE

R.SARAVANAN, PGET, L&T UAE

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R.SARAVANAN, PGET, L&T UAE

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R.SARAVANAN, PGET, L&T UAE

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Power in UAE..?
 Production capacity – 18.74 GW. (lack in peak seasonal times)  Lack of natural gas  Gulf Cooperation Council – UAE, Kuwait, Qatar, Bahrain, Saudi Arabia & Oman

 GCC began region-wide power grid – demand
 UAE has no spare power capacity  Phase 3 of GCC grid to southern system of UAE  In Dec’2009 $20 billion contract to Korean Electric Power – 4 nuclear reactors  1st reactor may 2017 – each reactor 1400 MW

R.SARAVANAN, PGET, L&T UAE

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Electric power transmission..?
 The bulk transfer of electrical energy, from generating power plants to substations  Power is usually transmitted through overhead power lines  Underground power transmission has a significantly higher cost and greater operational limitations - urban & sensitive areas

Overhead Power lines..?
 An electric power transmission line suspended by towers  It is the lowest-cost method of transmission for large quantities of electric energy (most of insulation by air)  The bare wire conductors on the line are generally made of aluminum R.SARAVANAN, PGET, L&T UAE 5

Transmission tower..?
• Tall structure usually a Steel lattice tower, used to support an overhead power line • Electricity pylon – UK & parts of Europe • Ironman – Australia • Hydro tower in parts of Canada

R.SARAVANAN, PGET, L&T UAE

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R.SARAVANAN, PGET, L&T UAE

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TOWER GEOMENTRY

EXTENSIONS BRACINGS

ANATOMY

R.SARAVANAN, PGET, L&T UAE

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Tower Anatomy
 Peak - supports G.W  Cage - b/w peak & tower body  Cross Arm - Support Conductor/G.W  Boom – supports power conductors (horizontal)  Tower body – main portion, connects cage/boom to foundation/(leg/body )extensions R.SARAVANAN, PGET, L&T UAE 9

R.SARAVANAN, PGET, L&T UAE

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Bracings
 Provided for interconnecting the legs  To afford desired slenderness ratio for economical tower design  Framing angle b/w bracings & main leg members shall not be < 15 degree  Patterns are a) Single web system b) Double web or warren system c) Pratt system d) Portal system e) Diamond Bracing system f) Multiple Bracing System

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1.Struts are designed in compression & Diagonals in tension 2.NARROW BASE 3.66Kv single circuit

1.Tension diagonal give eff.support to compression one @ pt of connections 2.Used in both large and small towers

1.Shear carried by diagonal member(t) 2.Large deflection under heavy loads 3.Unequal shears at top of four stubs for design

R.SARAVANAN, PGET, L&T UAE

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1.1half of Horizontal member in T & another C 2.Advantageous to use it in BOTTOM panel 3.Extensions & Heavy river crossing

1. Similar to waran system 2.Horizontal member carry no primary loads designed as redundant supports

1.Increse in strenght reducing member sizes 2.Increase in No.of bolts, fabrication & erection cost, 3.Overal reduction in Wt & cost of steel

R.SARAVANAN, PGET, L&T UAE

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Tower Extension
Body Extension

Body Extension Leg Extension

Used to Increase the height of tower to obtain the reqd min Ground clearance & over road crossings, river crossings, ground obstacles Body extensions upto 7.5m height in steps 2.5m can be used & thus form a part of standard tower Extensions having greater heights (25m) the suitability is checked by reducing span length and angle of deviation. Practice in tower industry is also to specify negative body extension (portion of tower body is truncated) R.SARAVANAN, PGET, L&T UAE 14

Leg Extension
Tower Leg extensions are required when the tower was spotted in the undulated surface / Hilly terrain.

While spotting the tower locations in hilly areas requires more benching or revetment or both are involved , but suitable hill side (leg extensions) can be used to minimize benching or revetment or both.

Two types of...
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