The invention generally relates to the area of overhead transmission cables. In particular, the invention relates to a new aluminum based overhead transmission cable having low losses and a process for producing the same.

BACKGROUND OF THE INVENTION

Overhead transmission cables lines are unique. They involve public safety directly both in terms of electrical clearances and structural adequacy. One of the fundamental limitations on power flow through overhead lines is limiting the conductor temperature to a level which neither causes a reduction in the conductor strength nor causes an increase in sag sufficient to infringe upon minimum electrical clearances to ground, buildings and other conductors.

Some of the aluminum based overhead transmission cables of the Applicant which are available in the market include:
• All Aluminum Conductor (AAC): AAC conductor consists of concentric lay stranded Aluminum conductor made up of hard drawn 1350 aluminum alloy.
• All Aluminum Alloy Conductor (AAAC): AAAC conductor consists of one or more layers of Aluminum-Magnesium-Silicon alloy wires.
• Aluminum Conductor Alloy Reinforced (ACAR) Conductors: ACAR conductor is a concentric-lay stranded conductor made up of Aluminum 1350-H19 on high strength Aluminum-Magnesium–Silicon (AlMgSi) alloy core (Aluminum Alloy 6201strands).
• Al-59 Conductors: AL-59 conductors are homogenous alloy conductors belonging to Aluminium + Magnesium + Silica Alloy type. Al-59 conductors have a conductivity of 59% and hence have lesser DC resistance & higher current carrying capacity.
• Eco Series Conductors; Eco Series conductors consist of trapezoidal shaped special aluminum alloy containing magnesium, silicon and copper stranded with round core. The trapezoidal shape provides compactness to the extent of96%.

The Indian Power sector is evolving from thermal based system to much greener Renewable based Power source system. India has set an ambitious target of 175GW of renewable energy generation by 2022. By end of 2018 the government of India has Installed 74.79GW of renewable energy already and still a long way to go for completion of ambitious target. The transmission of the generated clean energy is very crucial with minimized losses.

The demand for the low loss conductor (having losses lower than ECO Conductor as marketed by the Applicant was realized) for transmission of the generated clean energy is therefore outstanding.

SUMMARY OF THE INVENTION:

This summary is provided to introduce a selection of concepts in a simplified format that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention, and nor is it intended for determining the scope of the invention.

Accordingly, the present invention provides an aluminum based overhead transmission cable (item 30 in figure-1) that comprises an aluminium core (item 10 in figure-1) having plurality of alumunium wires, each of the alumunium wire having electrical conductivity of 59% International Annealed Copper Standard (IACS); and plurality of EC grade aluminum wires (item 20 in figure-1) stranded around the aluminium core, each of the EC grade aluminium wire having electrical conductivity of 61% IACS.

To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings (figure-1). It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES:

In order that the invention may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying drawings, where like reference numerals refer to identical or functionally similar elements throughout the separate views. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present invention where:

Figure 1 illustrates a sectional view of an aluminum based overhead transmission cable (30) constructed in accordance with the teachings of the invention.

It may be noted that to the extent possible, like reference numerals have been used to represent like elements in the drawings. Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of aspects of the present invention. Furthermore, the one or more elements may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION OF THE INVENTION:

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawing and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.

As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

As used herein, and unless the context dictates otherwise, the terms "coupled to", “connected to”, “operably connected to”, “operatively connected to” are intended to include both direct connection / coupling (in which two elements that are coupled / connected to each other contact each other) and indirect coupling / connection (in which at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with" are used synonymously. Similarly, the terms “connected to” and “connected with” are used synonymously.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The device, methods, and examples provided herein are illustrative only and not intended to be limiting.

The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Referring to figure 1, the present invention provides an overhead transmission cable (30). The overhead transmission cable (30) as provided by the present invention is being referred to as aluminum based overhead transmission cable. The aluminum based overhead transmission cable (30) comprises an aluminium core (10) having plurality of alumunium wires and a plurality of EC grade aluminum wires (20) stranded around the aluminium core (10).

The present invention also provides a process of producing aluminum based overhead transmission cable, which comprises providing an aluminium core (10) having plurality of aluminium wires, each of the aluminium wire with electrical conductivity of 59% International Annealed Copper Standard (IACS); and standing plurality of EC grade aluminum wires (20) around the aluminium core (10), each of the EC grade aluminium wire with electrical conductivity of 61% IACS.

In an embodiment of the invention, the aluminium core (10) comprises a central aluminium wire and a plurality of peripheral aluminium wires stranded around the central aluminium wire.

In an embodiment of the invention, the overall conductivity of the aluminium based overhead transmission cable to be 61.5% IACS.

In an embodiment of the invention, the shape of the central aluminium wire (10) is round.

In an embodiment of the invention, the shape of the peripheral aluminium wires (10) is round.

In an embodiment of the invention,the shape of the EC grade aluminum wire (20) is trapezoidal.

In an embodiment of the invention, the aluminium core (10) is made of AlMgSi alloy.

In an embodiment of the invention, the aluminum based overhead transmission cable (30) has minimized power losses and thereby allows for transmitting power more efficiently. By way of a non-limiting embodiment, the aluminum based overhead transmission cable (30) can reduce the power losses upto 3% compared to normal ECO conductor of similar outer diameter.

In a more specific embodiment, the Aluminum based overhead transmission cable (30) comprises of two different types of Aluminium to achieve reduced losses in transmission line. The Aluminum based overhead transmission cable (30) comprises has AlMgSi Alloy with higher tensile strength and with 59.0% conductivity (IACS) in the inner layer(s) and normal trapezoidal shaped EC grade aluminium with 61% conductivity (IACS) in the outer layer(s). The combination of Al59 Alloy with EC grade aluminium is surprisingly providing the conductor better conductivity than Purely alloy based conductor. The average conductivity of Al59 conductor is 59.9% (IACS) whereas for the average conductivity of the new Aluminium based overhead transmission cable under this application is about 62% (IACS). The increase in conductivity facilitates for increased power transfer and lower losses.

Parts of new Aluminum based overhead transmission cable:
The inner layer(s) of aluminium core has concentrically stranded round wire core of AL59 (Al-Mg-Si alloy) as per SS4240813 with 58.84% conductivity (IACS) on individual wire.

The trapezoidal shaped normal hard drawn EC grade aluminium with 61% Conductivity (IACS) is stranded over the core.

Areas of Application of the new Aluminum based overhead transmission cable:
• Replacement of Al59 / ECO Series conductor for reducing losses
• Renewable Energy segment
• In Distribution Lines of 11kV to 66kV for reducing losses
• Any other application as chosen by the User (customers)

Uniqueness of the new Aluminum based overhead transmission cable:
• The new Aluminum based overhead transmission cable is Combination of Al-Mg-Si Alloy Aluminium Strands with Avg.59.9% % IACS as core of the conductor and EC Grade Aluminium Strands with Avg. 62% IACS as outer layers of conductor.
• The Combination of Aluminium Mg-Si Alloy With EC grade aluminium has Overall Avg. conductivity in conductor to be 61.5 %(IACS).
• The Ultimate tensile Strength in the conductor will be in the range of 160-260Mpa.
• The ratio of Al-Mg-Si alloy area to EC grade Aluminium area may be less than 25%.

Advantages of the new Aluminum based overhead transmission cable:
• The new Aluminum based overhead transmission cable is environmentally friendly which helps in reducing the carbon emissions drastically by 1,34,834 Tons/30 years compared to corresponding ACSR conductor.
• Power Saving (lower losses) up to 3% compared to ECO Series Conductor (as being marked by the Applicant), up to 30% Compared to Al59 Conductor and up to 40% compared to ACSR Conductor.
• The new Aluminum based overhead transmission cable will have lower operating temperature with that of ECO Series Conductor for same power transfer which will aid in lowering sag.
• Ease of Manufacturing
• Light in weight compared to ACSR for same power transfer
• Higher Conductivity up to 60% over cross section area of conductor

A comparison between the performance of the new Aluminum based overhead transmission cable and the performance of the ECO Series Conductor (as being marked by the Applicant) is provided herein below in the form of Table1.
Table 1:

S.NO. PARTICULARS Unit

Conductor Code Name
- ECO Series (existing product) Product of the Invention
A Conductor Parameters
Overall Diameter of Conductor Mm 22.00 23.00
Total area of the conductor mm2 353.1 380.63
Nominal Weight of Conductor Kg/km 973 1049
Rated Strength of the conductor KN 81.95 65.83
Maximum DC Resistance at 20°C of Conductor Ohm/Km 0.08460 0.0762
Modulus of Elasticity kg/sqmm 6936 6086
Temperature Coefficient of Resistance 0.0039 0.004
B Power Transfer Capacity For 30MW
Ampacity in Single Conductor A 583 583
Conductor temp. at above ampacity Deg. C 87.76 84.83
Power Transfer @ p.f -0.9 MW 30.0 30.0
A.C Resistance at above ampacity Ohm/Km 0.1074 0.0963
Power loss per Ckt @ Load Factor-
0.15 & 50 Km Line Length KW 822 736
Power Loss Benefit over ECO Panther Conductor --- 10% better than ECO
Max. Sag at 60 m Span Mtrs 0.94 1.00

C Max. Power Transfer Capacity
Ampacity in Single Conductor A 656 585
Conductor temp. at above ampacity Deg. C 95 85
Power Transfer MW 34.0 30.0
Max. Sag at 60 m Span at above Temp Mtrs 1.04 1.00
D SAG & TENSION Limits
Span Length Mtr 60 60
Factor of safety at everyday temp and no wind Kg 25% 25%
Everyday temperature 32 °C & No Wind Condition Kgf 2089 1698
Everyday temperature 32 °C & Full wind condition
(Wind Pressure - 71.5 Kg/m2)
Kgf
2256
1923
NOTE1: Assumption for Ampacity Calculation : Wind Speed : 0.56 m/s , Solar absorptivity-0.8 , Emissivity - 0.45 , Solar Radiation -1045 W/m2 , Ambient Temp. 50deg.C, Elevation 0 m,Wind Pressure 71.5 Kg/Sq.m, Span - 60 mtr, if there is change in any assumption and conditions the value and design may vary.
NOTE2: Power & Loss assumption for calculations: P.F 0.9, Single circuit single conductor, voltage 33kV.

While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

We Claim:

1.An aluminum based overhead transmission cable (30) comprising:
an aluminium core (10) having plurality of alumunium wires, each of the alumunium alloy wire having electrical conductivity of Avg. 59.9% International Annealed Copper Standard (IACS); and
plurality of EC grade aluminum wires (20) stranded around the aluminium core, each of the EC grade aluminium wire having electrical conductivity of Avg.62% IACS.

2. The aluminum based overhead transmission cable as claimed in claim 1, wherein the aluminium core (10) comprises a central aluminium wire and a plurality of peripheral aluminium wires stranded around the central aluminium wire.

3. The aluminum based overhead transmission cable as claimed in claim 1, wherein the overall conductivity of the aluminium based overhead transmission cable is in the range 61.5% IACS.

4. The aluminum based overhead transmission cable as claimed in claim 1, wherein shape of the central aluminium wire is round.

5. The aluminum based overhead transmission cable as claimed in claim 1, wherein shape of the peripheral aluminium wires is round.

6. The aluminum based overhead transmission cableas claimed in claim 1, wherein the shape of the EC grade aluminum wire (20) is trapezoidal.

7. The aluminum based overhead transmission cable as claimed in claim 1, wherein the aluminium core (10) is made of AlMgSi alloy.

8. A process of producing aluminum based overhead transmission cable, comprising:
providing an aluminium core (10) having plurality of aluminium wires, each of the aluminium wire with electrical conductivity of Avg59.9% International Annealed Copper Standard (IACS); and
standing plurality of EC grade aluminum wires (20) around the aluminium core (10), each of the EC grade aluminium wire with electrical conductivity of Avg.62%IACS.