FORM-2
THE PATENT ACT,1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
(As Amended)
COMPLETE SPECIFICATION (See section 10;rule 13)
"COMPACT TOWER FOR TRANSMISSION LINES"
Tata Consulting Engineers Limited, a corporation organized and existing under the laws of India, of Matulya Center “A”, 1st floor, 249, Senapati Bapat Marg, Lower Parel (west), Mumbai 400 013, India.
The following specification particularly describes the invention and the manner in which it is to be performed:

BACKGROUND OF THE INVENTION
The present invention is focused to achieve cost effective and compact tower designs for trans-mission lines to accommodate more number of circuits in a single corridor by keeping the struc-ture heights within limits, thereby increasing the power transfer capacity of the line.
Constructing new transmission line corridor pose lots of challenges both in terms of Right of Way availability and the time consumed in obtaining the statutory approvals like forest clear¬ance, for example. Some regions having huge power generation potential, face challenges in im-plementing additional transmission line infrastructure for evacuating the power to load centers, due to the limited corridor availability in the highly congested area. Moreover, many transmis¬sion line infrastructures are nearing its end of life, where the corridor will be available for con¬structing the new lines in the near future. This makes it the right time to think of implementing high capacity transmission lines using compact designs, which cater maximum power evacuation capability in the limited corridor available.
In conventional design, as the number of circuits supported by a single structure is increased, the height and weight of the structure is increased due to the increase in conductor spacing and the huge forces exerted by the cross-arms due to the increased conductor loads.
The new transmission line tower in the preferred embodiment, minimizes these concerns while essentially increasing the capacity of the line in a cost effective manner.
SUMMARY OF THE GENERAL INVENTIVE CONCEPT
In all embodiments of the invention, a high-capacity, overhead transmission line design offers performance advantages relative to conventional configurations now in use in the electric utility industry. This design provides optimal distribution of forces from the cross-arms to the tower body in addition to the reduction in cross spacing, resulting in reduced tower height; making the design more compact and cost effective.
The preferred embodiment of the invention represents multiple-circuit including but not limited to double-circuit, quadruple-circuit, hextuple-circuit lines, characterized by a compact interphase configuration using single and/or bundled conductors suspended from (or) terminated to struc-

tures with reduced height. The new structure preferably is comprised of a single and/or multiple intermediate tie members in cross-arms to achieve uniform load distribution and optimal cross-arm spacing; resulting in considerable reduction in tower weight. The phase conductors of indi¬vidual circuit are preferably arranged in triangular form and/or horizontal form in order to reduce the overall height of the tower.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description of the example embodiments refers to the accompanying figures that form a part thereof. The description provides explanations by way of exemplary embodiments. It is to be understood that other embodiments may be used having mechanical and electrical chang-es that incorporate the scope of the present invention without departing from the spirit of the in-vention.
In addition to the features mentioned above, other aspects of the present invention will be readily apparent from the following descriptions of the drawings and exemplary embodiments; wherein like reference numerals across the several views refer to identical or equivalent features, and wherein:
FIG. 1 illustrates the preferred embodiment of the double-circuit transmission line of the present invention;
FIG. 2 illustrates one conventional transmission line in use (prior art);
FIG. 3 illustrates the preferred embodiment of the quadruple-circuit transmission line of the pre-sent invention;
FIG. 4 illustrates the preferred embodiment of the hextuple-circuit transmission line of the pre-sent invention;
FIG. 5 illustrates one embodiment of conventional quadruple-circuit transmission line; FIG. 6 illustrates another embodiment of conventional quadruple-circuit transmission line;
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT(S)
The preferred embodiment of double-circuit (or multiple-circuit) tower features a compact de¬sign with conductors of two (or more) phases supported by single cross-arm. This configuration

reduces the height of the tower, whereas it increases the length of the cross-arm. Intermediate tie members are added to cross-arms, supporting conductors of more than one phases, for better load transfer from cross-arm to the tower body. The following criterion defined in Eq. (1) is followed to determine the number of intermediate tie members:
Ntie-pc = Nphase - 1 Eq. (1)
Where,
Ntie-pc= Number of intermediate tie members for cross-arm supporting phase conductors.
Nphase = Number of phases supported by the cross-arm.
FIG 2 shows a conventional cross-arm arrangement of double-circuit tower. Each cross-arm has a bottom member (9) and a main tie member (3). FIG. 1 shows the preferred embodiment of a double-circuit tower of the present invention. The bottom cross-arm, support conductors of two phases and hence one intermediate tie member (1) is utilized. FIG. 3 shows the preferred embod-iment of a quadruple-circuit tower of the present invention. The middle cross-arm support con-ductors of two phases and therefore one intermediate tie member (1) is provided. The bottom cross-arm support conductors of three phases and therefore two intermediate tie members (1) and (2) are provided. This tower is compared with two towers having conventional cross-arms with-out intermediate tie members, with similar conductor arrangement as in FIG 3. The summary of structural analysis is tabulated in Table 1 and Table 2.
TABLE 1

Comparison of Tower designs of Conventional and Present Invention
(Forces on tower body near cross-arms)
Force on Member
Member ID
(Typ-1 / Typ-2 /
New) Conventional De-sign – 1 (FIG 5) Conventional De-sign – 2 (FIG 6) New Design (FIG 3)
H11 / H21 / H31 x y z
H12 / H22 / H32 1.5x 0.7y 1.1z
H13 / H23 / H33 0.4x 1.2y 1.1z
H14 / H24 / H34 1.4x 0.9y 1.3z
H15 / H25 / H35 0.7x 0.2y 0.3z

As shown in FIG 5 (Conventional Design – 1), in case of towers supporting multiple-circuits, if conductors of more than one phases are supported by single cross-arm (5) and (6), the force transferred to the tower body increases (Table 1) and hence vertical arrangement of conductors with one phase per cross-arm, as shown in FIG. 2 is generally followed. On the other hand, if the base area of cross-arm connection to the tower body is increased by raising the level of connec-tion of main tie member (3) as shown in FIG 6 (Conventional Design – 2), the force on tower body (Table 1) get reduced. However, due to the non-uniform distribution of forces in the hori-zontal members (H21), (H22), (H23), (H24) and (H25), the forces (Table 2) in the main legs (L21), (L22), (L23), (L24) and (L25) are substantially higher. In addition to this, the cross-arm spacing is also needs to be increased to achieve required electrical clearances (R1), (R2), (R3) as indicated in (7), at various swing angles (ϴ1), (ϴ2) of conductor (16) and suspension or pilot in-sulator (17). These will increase the overall height of the tower at least by 3.5 m compared to Conventional Design – 1.
In the present invention, these problems are addressed by introducing the intermediate tie mem-bers as shown in FIG 3. As seen from Table 1, the forces transferred by the cross-arm to the tow-er body are not uniform in both the conventional designs. Whereas, in the new design, the forces from each cross-arms with intermediate tie members are uniformly distributed to the tower body to the extent possible, thereby minimizing the forces in tower legs.
TABLE 2

Comparison of Tower designs of Conventional and Present Invention (Forces on tower legs near cross-arms)
Member ID Force on Member % reduction of forces in tower legs
(Con-1 / Con-2 / New) Conven-Conven¬tional
tional De-Design –
sign – 2 1 New De-sign With respect With respect
to Conven- to Conven-tional Design tional Design – 1 – 2
L11 / L21 / L31 x1 0.9x1 0.3x1 70% 68%
L12 / L22 / L32 X2 X2 0.4x2 59% 59%
L13 / L23 / L33 X3 X3 0.7x3 28% 28%
L14 / L24 / L34 x4 1.1x4 0.8x4 17% 26%
L15 / L25 / L35 x5 0.9x5 0.4x5 55% 50%

The addition of intermediate tie members has resulted in up to 70% reduction of forces on tower legs, which contribute to the reduction in overall weight of the tower. Moreover, this design pro-vides the required electrical clearances (7) at a lesser cross-arm spacing when compared to the conventional designs in use, thereby reducing the overall height of the tower by 10%. In addition to these, this design also helps to improve the structural stability of the cross-arms by distributing the conductor loads directly to tower body through the intermediate tie members, as they are connected exactly at the conductor attachment points in the cross-arm.
Table 3 shows the overall comparison of the double-circuit, quadruple-circuit and hextuple-circuit towers based on the new design against conventional designs in use. From the table, it is evident that the new design has yielded to substantial reduction in the height and weight of the tower with the reduction in overall cost of the tower.
TABLE 3

Comparison of Tower designs of Conventional and Present Invention
(Overall comparison)
Height of tower Weight of tower Right of way
(m) Conventional (MT) (m)

New Conventional New Conventional New
Design Design Design Design Design Design
Double-Circuit a1 0.8a1 b1 0.8b1 c1 c1
Quadruple-Circuit a2 0.9a2 b2 0.8b2 c2 c2
Hextuple-Circuit a3 0.9a3 b3 0.8b3 c3 c3
It is evident from Table 3 that the use of intermediate tie members has yielded a considerable reduction in height and weight of the tower in double-circuit as well as multiple-circuit configu-rations, when compared to the conventional designs of similar type that are already in use. There is no change in the Right of Way requirement in the present invention when compared to the conventional tower design in use. Due to the reduction in weight of the tower, there is a signifi-cant reduction in capital cost and carbon footprint as well, due to less usage of steel in the new

designs compared to the conventional designs that are presently in use. Apart from the ad-vantages in cost reduction, the reduction in height in the present invention also enables the use of overhead lines by providing such compact tower, at sensitive locations having restriction in structure height.
The tower of the present invention is capable of accommodating multiple sub-conductor per phase with two-, three-, four-conductor or larger phase bundles. It also supports usage of differ-ent types of phase conductors with symmetrical and/or asymmetrical bundles. Provision of two shield wires is considered in the present invention to provide preferably twenty-degree shield angle for the outermost conductors in conformance with the statutory rules. The cross-arms for shield wire (10) shall also be supported by intermediate tie members when the cross-arm length is higher, to result in optimized structure. The following criterion defined in Eq. (2) shall be fol-lowed to decide the use of intermediate tie members in cross-arms supporting shield wires:

Where,
Ntie-pc = Number of intermediate tie members for cross-arm supporting shield wire.
Wc s = Shield wire cross-arm spread (11) in meters.
Wt b = Width of tower body at Shield wire cross-arm level (12) in meters.
While certain embodiments of the present invention are described in detail above, the scope of the invention is not to be considered limited by such disclosure, and modifications are possible without departing from the spirit of the invention as evidenced by the following claims:

We claim:
1. A lattice tower structure to support transmission line conductors in tension at certain an¬
gle of deviation, comprising:
cross-arms with intermediate tie members to support conductors of two or more phases ter-minated with tension insulator strings.
three phase conductor bundles per circuit to transmit electrical power in an electrical power transmission system, each conductor bundle comprised of one or multiple sub-conductors spaced at uniform distance throughout the line;
wherein the three phase conductors of a circuit are spaced either in triangular arrangement or in horizontal arrangement such that at least one of the cross-arms support conductors of two or more phases.
wherein the three phase conductors of a circuit if spaced in triangular arrangement, they are equally spaced from each other such that they form the corners of an equilateral triangle, to improve the geometric mean distance, resulting in reduction of line inductance, thereby increasing the capacity of the line.
2. The transmission tower structure according to claim 1, wherein the first intermediate tie member (1) is connected to the tower leg (8) at one end, and the other end is connected to the bottom horizontal main member of the cross-arm (9), where the first phase conductor near to tower leg (8) gets terminated through tension insulator string.
3. The transmission tower structure according to claim 1, wherein the second intermediate tie member (2) is connected at one third length of the first intermediate tie member (1) at one end, and the other end is connected to the bottom horizontal main member of the cross-arm (9), where the second phase conductor near to tower leg (8) gets terminated through tension insula-tor string.
4. The transmission tower structure according to claim 1, wherein the main tie member (3) is connected at the mid-point of the first intermediate tie member (1) (in case the cross-arm

support conductors of two phases) at one end, and the other end is connected to the bottom hor¬izontal main member of the cross-arm (9), at the tip, where the outermost phase conductor gets terminated through tension insulator string.
5. The transmission tower structure according to claim 1, wherein the main tie member (3) is connected at one third length of the second intermediate tie member (2) (in case the cross-arm support conductors of three phases) at one end, and the other end is connected to the bot¬tom horizontal main member of the cross-arm (9), at the tip, where the outermost phase con¬ductor gets terminated through tension insulator string.
6. The transmission tower structure according to claim 1, wherein one end of the intermedi-ate tie member (13) of the cross-arm supporting shield wire is connected to the tower leg (8), at the point where the main tie member (3) of top cross-arm connects to the tower leg(8) (in case the top cross-arm (4), support conductors of one phase), and the other end is connected to the top horizontal main member of the cross-arm (15), at its mid point.
7. The transmission tower structure according to claim 1, wherein one end of the main tie member (14) of the cross-arm supporting shield wire is connected at the mid-point of the first intermediate tie member (13) (in case the top cross-arm (4), support conductors of one phase), and the other end is connected to the top horizontal main member of the cross-arm (15), at the tip, where the shield wire gets terminated through tension clamps.
8. The transmission tower structure according to claim 1, wherein one end of the main tie member (14) of the cross-arm supporting shield wire is connected at the mid-point of the first intermediate tie member (1) of top cross-arm, at the point where the main tie member (3) of top cross-arm connects to the first intermediate tie member (1) of top cross-arm (4) (in case the top cross-arm (4), support conductors of two phases), and the other end is connected to the top hor¬izontal main member of the cross-arm (15), at the tip, where the shield wire gets terminated through tension clamps.

9. The transmission tower structure according to claim 1, wherein one end of the main tie
member (14) of the cross-arm supporting shield wire is connected at one third length of the
first intermediate tie member (1) of top cross-arm, at the point where the second intermediate
tie member (2) of top cross-arm connects to the first intermediate tie member (1) of top cross-
arm (4) (in case the top cross-arm (4), support conductors of three phases), and the other end is
connected to the top horizontal main member of the cross-arm (15), at the tip, where the shield
wire gets terminated through tension clamps.
10. The transmission tower structure according to claim 1, wherein the lattice tower
structure to support transmission line conductors in suspended form, comprising:
cross-arms with intermediate tie members to support conductors of two or more phases sus-pended with suspension insulators strings.
three phase conductor bundles per circuit to transmit electrical power in an electrical power transmission system, each conductor bundle comprised of one or multiple sub-conductors spaced at uniform distance throughout the line;
wherein the three phase conductors of a circuit are spaced either in triangular arrangement or in horizontal arrangement such that at least one of the cross-arms support conductors of two or more phases.
wherein the three phase conductors of a circuit if spaced in triangular arrangement, they are equally spaced from each other such that they form the corners of an equilateral triangle, to improve the geometric mean distance, resulting in reduction of line inductance, thereby increasing the capacity of the line.
11. The transmission tower structure according to claim 10, wherein the first interme-diate tie member (1) is connected to the tower leg (8) at one end, and the other end is connect-ed to the bottom horizontal main member of the cross-arm (9), where the first phase conductor near to tower leg (8) is suspended through suspension insulator string.
12. The transmission tower structure according to claim 10, wherein the second in-termediate tie member (2) is connected at one third length of the first intermediate tie member (1) at one end, and the other end is connected to the bottom horizontal main member of the

cross-arm (9), where the second phase conductor near to tower leg (8) gets suspended through suspension insulator string.
13. The transmission tower structure according to claim 10, wherein the main tie member (3) is connected at the mid-point of the first intermediate tie member (1) (in case the cross-arm support conductors of two phases) at one end, and the other end is connected to the bottom horizontal main member of the cross-arm (9), at the tip, where the outermost phase conductor gets suspended through suspension insulator string.
14. The transmission tower structure according to claim 10, wherein the main tie member (3) is connected at one third length of the second intermediate tie member (2) (in case the cross-arm support conductors of three phases) at one end, and the other end is connected to the bottom horizontal main member of the cross-arm (9), at the tip, where the outermost phase conductor gets suspended through suspension insulator string.
15. The transmission tower structure according to claim 10, wherein one end of the intermediate tie member (13) of the cross-arm supporting shield wire is connected to the tower leg (8), at the point where the main tie member (3) of top cross-arm connects to the tower leg(8) (in case the top cross-arm (4), support conductors of one phase), and the other end is connected to the top horizontal main member of the cross-arm (15), at its mid point.
16. The transmission tower structure according to claim 10, wherein one end of the main tie member (14) of the cross-arm supporting shield wire is connected at the mid-point of the first intermediate tie member (13) (in case the top cross-arm (4), support conductors of one phase), and the other end is connected to the top horizontal main member of the cross-arm (15), at the tip, where the shield wire gets suspended through suspension clamps.
17. The transmission tower structure according to claim 10, wherein one end of the main tie member (14) of the cross-arm supporting shield wire is connected at the mid-point of

the first intermediate tie member (1) of top cross-arm, at the point where the main tie member (3) of top cross-arm connects to the first intermediate tie member (1) of top cross-arm (4) (in case the top cross-arm (4), support conductors of two phases), and the other end is connected to the top horizontal main member of the cross-arm (15), at the tip, where the shield wire gets suspended through suspension clamps.
18. The transmission tower structure according to claim 10, wherein one end of the
main tie member (14) of the cross-arm supporting shield wire is connected at one third length of the first intermediate tie member (1) of top cross-arm, at the point where the second inter-mediate tie member (2) of top cross-arm connects to the first intermediate tie member (1) of top cross-arm (4) (in case the top cross-arm (4), support conductors of three phases), and the other end is connected to the top horizontal main member of the cross-arm (15), at the tip, where the shield wire gets suspended through suspension clamps.