Analysis and Design of 220kv Transmission Line Tower in Different Zones I & v With Different Base Widths a Comparative Study

INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH, VOL 1, ISSUE 4 ISSN 2347-428935 Analysis And Design Of 220kv Transmission Line Tower In Different Zones I & V With Different Base Widths – A Comparative Study Ch. Sudheer, K. Rajashekar, P. Padmanabha Reddy, Y. Bhargava Gopi Krishna Assistant Professor, Department of Civil Engineering GVPTC School of engineering, Rushikonda. Assistant Professor, Department of Civil Engineering, Andhra University Assistant Manager (Design), S.N.Bhobe & Associates Pvt Ltd. Abstract: -. In this study, an attempt is made that 220kV Transmission line tower is modeled using STADD Pro 2006. The towers are designed in two wind zones I & V with three different base widths 1/4, 1/5 &1/6 of total height of tower. Towers are modeled using parameters such as constant height, bracing system, angle sections and variable parameters of different Base widths and Wind zones. The loads are calculated from IS: 802(1995). After completing the analysis, the comparative study is done with respect to deflections, stresses, axial forces and weight of tower for all 6 different towers. 1. Introduction: 1.1Transmission line tower: The advancement in electrical engineering shows need for supporting heavy conductors which led to existence of towers. Towers are tall structures, their height being much more than their lateral dimensions. These are space frames built with steel sections having generally an independent foundation under each leg. The height of tower is fixed by the user and the structural designer has the task of designing the general configuration, member and the joint details (John D Holmes). A high voltage transmission line structure is a complex structure in that its design is characterized by the special requirements to be met from both electrical and structural points of view, the former decides the general shape of the tower in respect of its height and the length of its cross arms that carry electrical conductors(Visweswara Rao, G 1995). Hence it has given rise to the relative tall structures such as towers. The purpose of transmission line towers is to support conductors carrying electrical power and one or two ground wires at suitable distance. In this study, a 220kV Transmission line tower is modeled using STADD Pro 2006. The towers are designed in two wind zones I & V with three different base widths. 1.2 Conductor: A substance or a material which allows the electric current to pass through its body when it is subjected to a difference of electric potential is known as Conductor. The materials which are used as conductors for over head transmission lines should have the following electrical and physical properties.      It should have a high conductivity It should have tensile strength. It should have a high melting point and thermal stability. It should be flexible to permit us to handle easily and to transport to the site easily. It should be corrosion resistance. ACSR Conductors: Aluminium has an Ultimate Tensile Strength (U.T.S) of 16 – 20 kg / mm2 where as the steel has a U.T.S of about 136 kg / mm2. By a suitable combination of steel and aluminium the tensile strength of the conductor is increased greatly. Thus came into use the Aluminium Conductor Steel Reinforced (ACSR). Table 1: Conductor mechanical and electrical properties: Voltage Level Code Name of Conductor No. of conductor/ Phase Stranding/ Wire diameter Total sectional area Overall diameter Approx. Weight Calculated D.C resistance at 20 0C Min.UTS Modulus of elasticity Co – efficient of linear expansion Max. Allowable temperature 220kV ACSR “ZEBRA” ONE 54/3.18mm AL + 7/3.18mm steel 484.5 mm2 28.62 mm 1621 Kg/ Km 0.06915 ohm/Km 130.32 kN 7034 Kg/mm2 19.30 x 10-6/ 0C 750C 1.3 Earthwire: The earthwire is used for protection against direct lightning strokes and the high voltage surges resulting there from. There will be one or two earthwire depending upon the shielding angle or protection angle. The earthwire to be used for transmission line Copyright © 2013 IJTEEE. t2 = 00 C No Wind.15mm 54. t2 = 320 C Copyright © 2013 IJTEEE. of Circuits: Double circuit d) Wind: As per IS:875 part III. t2 = 320 C 75% Full Wind. Weight Calculated D. ii. t2 = 750 C No Wind.01m 1. Functions of Insulators: The insulators separate the current carrying conductors of a transmission line from their support structures to prevent the flow of current through the structure to ground and to provide necessary mechanical support to the conductors at a safer height above the ground level. weight of the conductors and weight of the technicians with tools. under all operating conditions.UTS Modulus of elasticity Co – efficient of linear expansion Max.INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH. Allowable Temp.45 mm 428 Kg/ Km 3.C resistance at 200C Min. i. Sag = The following combinations will be considered: No Wind. ISSUE 4 ISSN 2347-4289 36 Table 2: Earthwire mechanical and electrical properties Voltage Level Material of Earthwire No.4 Insulator Strings: Insulators are devices used in the electrical system to support the conductors or to support the conductors carrying at given voltages.375 ohm/Km 5710 Kg 19361 Kg/mm2 11. t2 = 320 C c) No. 220kV Galvanized steel ONE 7/3.50 x 10-6/ 0C 53 C 0 e) Tower Height: H = h1 + h2 + h3 +h4 Minimum Permissible Ground Clearance (h1): For 220kV h1 = 7. Details of tower configuration: a) Tower type: Suspension and self supporting tower. Mechanical: They should be strong to withstand maximum expected loading for different operating conditions such self – weight. Maximum Sag (h2): The sag tension calculation for the conductor and earthwire shall be made in accordance with the relevant provisions of IS: 5613 (part – 2 / sec – 1):1985 for the following combinations. . Their main functions may be summarized as follows. wind and ice loads. and 36% design wind pressure after accounting for drag co–efficient and gust response factor at minimum temperature. b) Bracing system: Pratt system From the above equation. of earthwire Stranding/ Wire diameter Total sectional area Overall diameter Approx. For the conductors with higher aluminium content normally used for 220kV lines increased sag of 2 to 4% of the maximum sag value is allowed. VOL 1. 100% design wind pressure after accounting for drag co – efficient and gust response factor at every day temperature. we get sag tension of the conductor (T2). Electrical: They should keep separate the conductors or other current carrying devices with support structures which are at ground potential. Two wind zones I & V with wind speeds 33 m/s & 50 m/s respectively are taken into consideration.55 mm2 9. T22 [T2 A E +A α E (t2 – t1) – T1] = A E 2. Full Wind. 8 277166. The maximum deflections in X.3 183547.5 -18.7 223663. base width at concrete level is the distance from the centre of gravity of the corner leg angle to that of the adjacent corner leg angle.5 135127. axial forces in the members and maximum deflections of the nodes in x.1 123970.704 8.9 -60.05 51608.10.2 168. Tower is modeled with 12 panels and is built up with steel angle section.3 -23.2 339702. y & z directions and the above parameters are compared in wind zones I & V with wind speed 33 & 50 m/s respectively.3 -20.7 109 76.4 252119.4 239.3 407419 368760 260576. 6.4 -83.900 -20.9 223834.4 137079. f) Tower Width: The width of the tower is specified at base.7 V -72.704 8.5866 m.38m. Base Width: The spacing between the tower footings i. 7.2 186225 173461 185998.direction I 98.e.7 327103.1 180881. Table 3: Maximum Axial Deflections Base Width (m) Zone 5.6 291877 265645 191371.5866 m. Y & Z direction are presented in figure 1.1 Type of tower Horizontal spacing between conductors(mm) 220kV Double Circuit (0 ) 9.. 2.5866 6. H = h1 + h2 + h3 +h4 = 33. y. tensile stresses in members in wind zones I & V with the base widths 5.86 3.6 287655.12 47892. Discussions and Results: The parameters of this study are maximum compressive and tensile stresses in the tower members. 6. & z directions in wind zones I & V with the base widths 5. .5866 432068.5 -23. 9. same angle sections and constant height.3 75883. 3. All the towers are having 12 panels.3 663334 559603 587120. Table 3 represents the maximum axial deflections of nodes in x.7 -18. ISSUE 4 ISSN 2347-4289 37 Sag value for different temperatures and for different wind conditions are calculated and the maximum value of the above combinations + 4% extra will gives the h2 of the conductor. Table 6.INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH.4 105047 96728 90378.8 506641 442819 332449. 8. Tables 4 & 5 represent the maximum axial force in tower members in zone I & V with 3 base widths.3 275876.9 -60.5 361839. The tower weight with different base widths is presented in figure 4. Tower with different base widths are modeled and loading conditions are considered for two different wind zones I & V.9 416218 378150 336236. The maximum compressive stresses with different base widths are Copyright © 2013 IJTEEE.4 90260 81828 52874.9 139285.7 Y –direction I V Z .7 V 216. waist and cross – arm / boom level.1 129246.704 8. Spacing of Conductors (h3): Vertical spacing between conductors (mm) 5.76 52804 48198 5. The variable parameters are base widths.27 5.704 m & 8.12.9 143089.05 55589.58 47861.586 Maximum Axial Deflections (mm) X – direction I -72. Loadings on Tower: Modelling Approach: Loads are calculated as per IS 802:1995 & CBIP manual. 4. different wind zones.704 m & 8.38m. Transmission Line Tower is modeled using STAAD PRO – 06.38 725345.6 306625.1 243563.4 591254 495289 480807 530769 455485 421085.7 6.7.7 304624.38 Vertical Clearance between Ground Wire and Top Conductor (h4): The same procedure is repeated as done in finding sag of the conductor (h2) but only difference is instead of conductor properties substitute earthwire properties.52 m. Table 4: Maximum Axial Forces in Zone – I Panel 1 2 3 4 5 6 7 8 9 10 11 12 member 104 204 304 404 504 604 704 804 904 1004 1104 1204 Base Widths (m) 6.4 -83. The maximum tensile stresses with different base widths are presented in figure 6.2 333643.3 183757 169289 104437. 8 & 9 represents the maximum compressive.8 201285.4 289215.2 269772.8 358970. and 3 cross arms with double circuit lines and ground wire at the peak. Table 5: Maximum Axial Forces in Zone – V Panel 1 2 3 4 5 6 7 8 9 10 11 12 member 104 204 304 404 504 604 704 804 904 1004 1104 1204 Base Widths (m) 5. VOL 1.3 82279.34 43629. The maximum axial forces in members are presented in figure 11.200 presented in figure 5.29 55571.9 81932.38 398540. 38 122.405 84.617 133.5866 225.613 87.269 209.931 141.direction in Zone I & V 5.219 216.direction in Zone I & V 300 250 200 150 100 50 0 5.INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH.752 201.203 Copyright © 2013 IJTEEE.872 45.872 45.382 215.465 8.568 175.538 182. 1 Deflection in Y .465 -5 -10 -15 -20 -25 5.517 85.107 79.5866 137.704 122.834 117.I Zone -V Deflection(mm) 224.735 143.156 Zone .706 47.38 -60.794 Deflection Base Width(m) Figure.557 -18.996 8.704 8.968 122.039 148.807 123.405 84. ISSUE 4 ISSN 2347-4289 38 Table 6: Maximum Compressive Stresses (N / mm2) in Zone – I with different base widths Panel 1 2 3 4 5 6 7 8 9 10 11 12 Member 104 204 304 404 504 607 708 810 907 1010 1124 1204 5. VOL 1.967 210.32 -23.787 84.704 129.126 124.969 0 -20 -40 -60 -80 Deflection in X .757 196.166 87.648 47.38 98.518 85.747 164.226 110.736 239.018 140.757 135.2 Deflection in Z .226 110.89 -20.601 202.946 156.775 78.3 49.5866 6.946 156.107 79.557 178.38 187.827 79.795 88.545 175. .928 229.5 123.5866 6.347 129.604 207.704 8.38 Table 7: Maximum Compressive Stresses (N / mm2) in Zone – V with different base widths Zone -V Panel 1 2 3 4 5 6 7 8 9 10 11 12 Member 104 204 304 404 504 607 708 810 907 1010 1124 1204 5.601 133.807 123.5866 6.239 168.085 141.99 Deflection -100 Base width(m) Figure.347 129.442 Base Width(m) Figure.413 116.617 133.838 144.845 137.686 6.753 109.827 79.613 189.direction in Zone I & V 0 Deflection(mm) 78.145 141.567 117.312 76.283 160.031 52.731 -72.775 Deflection(mm) Zone -1 6.465 -83.269 92.601 133.312 91.459 141.704 8. 071 -93.944 -115.846 -48.61 -61.762 -111.258 -59.305 151.846 -48.02 -82.269 -149.421 -83.759 -138.556 -52.849 6.704 -109.386 -75.664 -163.813 -104.0 62074.731 -120.768 -98.652 201.38 162.607 -192.4 Table 8: Maximum Tensile Stresses (N / mm ) in Zone – I with different base widths Zone -1 Panel 1 2 3 4 5 6 7 8 9 10 11 12 Member 109 202 302 402 502 602 709 825 906 1009 1127 1202 5.954 -175.61 -61.4 Table 9: Maximum Tensile Stresses (N/mm2) in Zone – V with different base widths Zone -V Panel 1 Member 109 202 302 402 502 602 709 825 906 1009 1127 1202 5.643 -110.024 186.468 -55.641 -104.716 -117.513 -104.5866 6.112 Weight(N) Weight (N) 64000 63000 62000 61000 60000 5.746 -141.876 -102.14 112.704 8.071 -93.601 2 6 7 8 9 10 11 12 Copyright © 2013 IJTEEE.643 -110.919 -105.641 -104. VOL 1. .386 -75.987 -100.314 -111.741 -68.523 -52.805 -194.377 -98.38 63034.601 8.262 -97.38 -130.5866 -198.939 -98.INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH.429 -101.115 146.844 -123.762 -111.876 -102.002 169.074 -128.69 -188.919 -105.21 -103.159 -121.337 -101. ISSUE 4 ISSN 2347-4289 39 Weight of Tower in Different Base widths 66000 65000 65632.205 -174.25 -174.83 184.314 -111.299 -117.159 8.393 -166.262 -97.228 6.259 115.704 -130.5866 -114.485 -73.818 -127.3 2 3 4 5 Base Width (m) Figure. 38m Tensile Stresses ( N/mm² ) 0 -50 -100 -150 -200 -250 109 202 302 402 502 602 709 825 906 1009 1127 1202 Member 1 2 3 4 5 6 7 8 9 10 11 12 ZONE .6 Maximum Compressive Stresses in Zone I & V with base width 6.I Figure. .5 Maximum Tensile Stresses in Zone I & V with base width 8.704m Compressive Stresses ( N / mm² ) 200 180 160 140 120 100 80 60 40 20 0 104 204 304 404 504 607 708 810 907 1010 1124 1204 1 2 3 4 5 6 7 8 9 10 11 12 Zone . VOL 1.I Member Figure.INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH. ISSUE 4 ISSN 2347-4289 40 Maximum Compressive Stresses in Zone I & V with base width 8.V Zone .38m Compressive Stresses(N/mm²) 250 200 150 100 50 0 104 204 304 404 504 607 708 810 907 1010 1124 1204 1 2 3 4 5 6 7 8 9 10 11 12 ZONE .7 Copyright © 2013 IJTEEE.V ZONE .I Member Figure.V ZONE . 5866m Zone . ISSUE 4 ISSN 2347-4289 41 Maximum Tensile Stresses in Zone I & V with base width 6.8 Maximum Tensile Stresses in Zone I & V with base width 5.704m Tensile Stresses (N / mm² ) 0 -20 -40 -60 -80 -100 -120 -140 109 202 302 402 502 602 709 825 906 1009 1127 1202 1 2 3 4 5 6 7 8 9 10 11 12 Member Zone . VOL 1.5866m Tensile Stresses (N / mm²) 0 -50 -100 -150 -200 -250 109 202 302 402 502 602 709 825 906 1009 1127 1202 1 2 3 4 5 6 7 8 9 10 11 12 Zone .V Zone .I Member Figure 9 Compressive Stresses (N/mm²) 250 200 150 100 50 0 Maximum Compressive Stresses in Zone I & V with base width 5.I Figure.V Zone .I 104 204 304 404 504 607 708 810 907 1010 1124 1204 1 2 3 4 5 6 7 8 9 10 11 12 Member Figure 10 Copyright © 2013 IJTEEE. .V Zone .INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH. Reference: [1].039 N/mm2 & in Zone –V is 156.400 KV Lines. IS: 802 (part 1/sec 1): 1995. 2. Maintenance and Renovation of ransmission ines”.INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH. Copyright © 2013 IJTEEE.04 5.5866m and 35% more than the values at base width of 8. . 6.38 6.704 m. loads and permissible stresses).5866 104 204 304 404 504 604 704 804 904 1004 1104 1204 Member Figure 12 Conclusions: 1. At base width 6. Sec. VOL 1. 7.38 6. IS: 5613 (Part 3/Sec 1): 1989 Code Of Practice For Design.704 m base width.5866 Figure 11 Axial Force in the Member in the Zone .N and Kuldi Singh. “Innovative Techniques for Design.617 N/mm2 at base width 6. At a base width of 6. in all directions. Section 1 .716 N/mm2 & at member 109 in Zone –V is 130. the tensile stresses are maximum at member 402 in Zone – I is 128.5 N in Zone – I and 663334 N in Zone – V at 6. ( 00 ). 3. installation And Maintenance For Overhead Power Lines.I & Zone .V 2500000 Axial Force(N) 2000000 1500000 1000000 500000 0 1 2 3 4 5 6 7 8 9 10 11 12 8.704m is having 15% more than the values at base width of 5.V. deflections are found to be maximum than other two base widths 5.380m The maximum axial deflection At a base width of 6. deflections in Z-directions shows maximum values in both Zone . When compared to X and Y directions.I & Zone . 5.Design. a er presented at the National Seminar conducted by Central Board of Irrigation and Power. ISSUE 4 ISSN 2347-4289 42 Axial Force in the member in Zone -I 1400000 1200000 1000000 800000 600000 400000 200000 0 104 204 304 404 504 604 704 804 904 1004 1104 1204 Member 1 2 3 4 5 6 7 8 9 10 11 12 Axial Force (N) 8. 8. [3]. Y & Z directions for both Zone .1 Materials and Loads. The compressive stresses are maximum at member 404 in Zone – I is 175. Part 3 . The maximum axial forces are 398540.V. 4.641 N/mm2. Construction. All the deflections are in permissible limits is less than H/100.380m in all X.704 m.704 5.704m. Use of structural steel in over head transmission line towers – code of practice (materials.5866m. [2]. Mathur G. No 06 SPL. VOL 1. International Journal of Earth Sciences and Engineering ISSN 09745904. pp 81-92. Vol. Journal of Computers and Structures. October 2011. Copyright © 2013 IJTEEE.3 March 2011 pp 2474 – 2485. Ghugal et al. Y. International Journal of Engineering Science and Technology. Visweswara Rao G (1995). 57. akshmi et al. [6]. pp 691-694. V. “O timum Designs for ransmission ine owers”. Volume 04. “Analysis and Design of Three and Four Legged 400KV Steel Transmission Line Towers: Comparative Study”. ISSUE 4 ISSN 2347-4289 43 [4]. [5]. “Study On Performance Of 220 Kvm/C Ma Tower Due To Wind”.INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH. M. 3 No. . ISSN: 0975-5462 Vol.