F report

AL 59 ALLOY CONDUCTOR SEMINAR REPORT-10

ABSTRACT

A new Aluminum alloy conductor having higher conductivity has been developed. By using

these special alloy conductors, electric utility can achieve significant saving in both

transmission and distribution lines. AL-59 alloy conductors are manufactured from Al-Mg-Si

(aluminum-magnesium-silica) rods. The conductor comprises of an inner core and

concentrically arranged strands forming the inner and outer layers of the conductor. ACSR

conductors are limited by a maximum current carrying capacity of 838 amperes. The material

of construction of AL-59 alloy conductors overcome this limitation enabling AL-59 alloy

conductors to transfer up to 1307 amperes of current and evacuate up to 1405 mw of power

(56 per cent higher than ACSR Conductors). Additionally, AL-59 alloy conductors have 9

per cent better 'strength to weight ratio' and 8 per cent lower sag compared with ACSR

conductors which enables effective optimization of tower designs and future proofing of the

grid. In view of development of new power transmission and distribution grids by global

power incumbents, AL-59 alloy conductors would have a special significance while

designing transmission line networks, as the properties of these conductors enable superior

power evacuation while optimizing the cost of the entire grid.

M.B.C COLLEGE OF ENGG & TECH DEPT. OF ELECTRICAL & ELECTRONICS ENGINEERING Page 1PEERMADE


INTRODUCTIONThe categories of conventional type of Aluminium and Aluminium alloy overhead

conductors available globally are:

Homogeneous Conductors

AAC – All Aluminium Conductors

AAAC – All Aluminium Alloy Conductors

Non – Homogeneous Conductors

ACSR – Aluminium Conductor Steel Reinforced

AACSR-Aluminium Alloy Conductor Steel Reinforced

ACAR – Aluminium Conductor Alloy Reinforced

For several years, distribution and transmission lines have been designed using aluminium

conductors steel reinforced (ACSR) or in some countries all aluminium alloy conductors

(AAAC). Both types normally have a conductivity calculated on the total area of 53-54%

copper (IACS). Since the mid-1970s the cost of producing electric energy has grown rapidly,

leading to an increase in the cost of losses. An attempt to find new conductor material

producing fewer losses in the network was started in Sweden at the beginning of the 1970s

and led in 1979 to the release of a new conductor standard called Al-59, where “59” stands

for its conductivity (IACS). Aluminium Conductors (i) All Aluminium Conducts (AAC) (ii)

All Alloy Aluminium Conductors (AAAC), and (iii) Aluminium Conductors Steel

Reinforced (ACSR) are used in Transmission and Distribution system to carry the generated

electrical energy from generating station to end user. The Electrical energy is normally

generated at the power stations far away from the urban areas where the consumers are

located. There is a large network of conductors between the generating stations and the

consumer. The network is called the Transmission and Distribution system. The

Transmission system is to deliver bulk power from power stations to the load centres and

large industrial consumers beyond the economical service range of the regular primary

distribution lines where as distribution system is to deliver power from power sector or

substations to the various consumers. This transmission and distribution system can employ

either overhead system or underground system. Transmission of power, overhead system

mainly due to low cost and some other advantages ACSR generally used or transmission line

and AAC and AAAC conductors for distribution of power carry out mostly the high voltage



transmission. For transmission and distribution of electric power the conductor material used

must have the following characteristics:

i) High conducting i.e. low specific resistance

ii) High tensile strength in order to withstand mechanical stress

iii) Low specific gravity in order to give low weight per unit volume

iv) Low cost in order to be used over long distance

v) Should not be brittle

Copper, Aluminium, Steel and Steel cored aluminium, galvanised steel conductors are

generally employed for this purpose and preferably stranded in order to increase the

flexibility (Solid wires, except of smaller sizes, are difficult to handle and when employed for

long spans tend to crystallize at the points of support because of the swinging in winds.

Stranded conductors usually have a central wire around which there are successive layers of

6, 12, 18, 24 wires. For 19 layers, the total number of individual wire is 3n (n+1). If the

diameter of each strand is torn diameter of the stranded conductors will be (2n+1) d. In the

process of manufacture adjacent layers are spiraled in opposite direction, so that the layers

are bound together. This method of construction is called as Concentric Lay, out of above

mentioned conducting materials, Aluminium is widely used due to its cheapness and many

others comparative advantages over other conducting materials. However, owing to the fact

that the line or co-efficient of expansion of aluminium is 104 times that of copper, the sag is

greater in aluminium wire, therefore, steel cored Aluminium (ACSR) wire is used to

compensate this property of Aluminium. The steel conductors used are galvanised in order to

prevent rusting and electrolytic corrosion. The AAC/AAAC/ACSR conductors for high

voltage transmission have first replaced the bore copper conductors where copper is scarce

and costly on the other hand EC grade Aluminium is easily available in India and as far as the

electric properties are concerned, aluminium is equally good being lighter in weight and for

same sage span length of the transmission could be increased in comparison to copper.

Keeping in view the simple technology involved AAC/ACSR/AAAC conductors up to 19

strand have been reserved for exclusive production in small scale sector. However,

Aluminium conductors up to 61 strand can be manufactured. Different types of aluminium

conductors manufactured are:

i) All Aluminium stranded conductors (AAC)



ii) Aluminium conductors, aluminized steel reinforced

iii) Aluminium conductors galvanised steel reinforced (ACSR)

iv) All Aluminum Alloy stranded Conductors (AAAC)

v) Aluminium conductors galvanised steel reinforced for extra high voltage (400 kV or

above) (ACSR)

HISTORYIn 1920’s, within about 20 years of introducing ACSR, France introduced for the first time a

new type of electric al conductor made of an alloy of aluminium with magnesium and silicon

alloy. Other European countries also developed similar material as their conductor material

US also followed the same in 1960’s The electrical conductor made of such alloy had higher

strength than EC grade aluminium of equal size with slight loss in conductivity. Due to the

increased strength the conductors did not require steel reinforced. AAAC thus made its

advent as the most suitable current carrier in transmission and distribution. IEC

recommendation number 208 provides an internationally acceptable standard for AAAC

(Aluminium Alloy Conductors). At the beginning of 70’s AB Electrokopper in Helinsburg

developed an alloy with the trade name DUCTALEX. It has a better conductivity than the

alloys developed by the France but a slightly lower mechanical strength.

This new conductor alloy was laboratory tested at the Swedish State Power Board with

respect to creep, corrosion resistance, self damping and fatigue strength, all tests showed the

same or better properties than the ordinary alloy. Tests were made on actual distribution lines

starting in 1975. As only satisfactory results were obtained the new alloy was installed in 400

KV line. The measurement of sag after five years showed a high degree of agreement with

what was predicted. Concurrent with all trials the Swedish Standardization Committee

worked out and issued the standards SS4240813 for AL-59 wires and SS4240814 for AL-59

conductors.



BASIS AND PRESUMPTIONS

The basis for calculation of production capacity has been taken on two shifts per day

basis on 75% efficiency.

The maximum capacity utilization on two shifts basis per day for 300 days a year.

During first year and second year of operations the capacity utilization is 60% and

80% respectively.

The unit is expected to achieve full capacity utilization from the third year onwards.

The salaries and wages, cost of raw materials, utilities, rents, etc. are based on the

prevailing rates. The cost factors may vary with time and location.

Interest on term loan and working capital loan has been taken at the rate of 12% on an

average. This rate may vary depending upon the policy of the financial

institutions/agencies from time to time.

The cost of machinery and equipments refer to a particular make / model and prices

are approximate.

The break-even point percentage indicated is of full capacity utilization.

The project preparation cost etc. whenever required could be considered under pre-

operative expenses.

The essential production machinery and test equipment required for the project have

been indicated. The unit may also utilize common test facilities available at

Electronics Test and Development Centers (ETDCs) and Electronic Regional Test

Laboratories (ERTLs) and Regional Testing Centers (RTCs)

MANUFACURING PROCESSES

The process of manufacturing of Aluminium Alloy Conductors (AAC), Aluminium

Conductor Steel Reinforced (ACSR) and All Aluminium Alloy Conductor (AAAC),

Aluminium 59 etc. involves the following process:

Drawing of aluminium alloy rod of 9.5mm dia into the required size through a set of

gradually reducing sizes of dies in wire drawing machine and wounded up on a spool.



The required number of spools fitted in the tubular stranding machine and stranded in

a wooden drum.

For ACSR and AAAC the alloy rod is drawn into 7.15 mm dia and put in furnace for

heat treatment at a constant temperature at 530oC for 40 minutes.

After heat treatment the heat treated alloy wire dipped into the cold water in a

quenching tank for 30 to 40 minutes within 6 to 10 seconds of heat treatment.

The quenched alloy wire then dried for 8 to 12 hours.

7.15 mm alloy wire then finally drawn into different sizes in wire drawing machine.

The drawn wire then subjected to ageing at 160oC temperature for 4 hours in furnace

on condition and kept inside furnace for on condition and kept inside furnace for

another 2 to 4 hours in furnace off condition.

After standing the alloy conductors in a 7 stand high speed tubular machines in 61

strand (7+54) multi layer stranding machine.

Stranded wire inspected and tested for resistance, elongation and breaking load before

finally dispatching to customer.

QUALITY CONTROL AND STANDARDS

Purity of aluminium for the items to be used in electrical and electronic industries

shall be 99.9%. The quality of the Aluminium conductors produced can be controlled

by sticky following the related IS specifications right from beginning of raw material:

Ensuring the correct quality of raw material as per IS 5484:1978 EC grade aluminium

rods produced by continuous casting and rolling. The aluminium content shall not be

less than 99.5% and copper conductors shall not be more than 0.04 per cent.

While manufacturing AAC, AAAC and ACSR Conductors strictly adhering to IS

Specification.

IS 398 (Part 1): 1996 for AAC

IS 398 (Part 2): 1996 for ACSR (Galvanised Steel Reinforce)

IS 398 (Part 3) For Aluminium Conductors, Aluminized Steel, Reinforced)

IS 398 (Part 4): 1994 AAAC (Aluminium, Magnesium silica

IS 398 (Part 5) AC Galvanized high voltage (400 kV and above)

IS 7623: 1993 Lithium base grease for industrial purpose

IS 1778: 1980 Use of Reels and drums for wounding conductors.



The test to be carried out as per above mentioned IS Specification are enumerated in

process flow chart of aluminium conductor manufacturing. Obtaining ISO

certification can further boost the credibility of the unit.


Fig. 1 Power Conductor Manufacturing Process: Rod manufacture

Fig. 2 Power Conductor Manufacturing Process: Rolling mill

Fig.3 Power Conductor Manufacturing Process: Wire Drawing

Fig.4 Power Conductor Manufacturing Process: Wire Stranding


AL 59 ALLOY CONDUCTOR

AL-59 alloy conductors are manufactured from Al-Mg-Si (aluminum-magnesium-silica)

rods. The conductor comprises of an inner core and concentrically arranged strands forming

the inner and outer layers of the conductor. ACSR conductors are limited by a maximum

current carrying capacity of 838 amperes. The material of construction of AL-59 alloy

conductors overcome this limitation enabling AL-59 alloy conductors to transfer up to 1307

amperes of current and evacuate up to 1405 mw of power (56 per cent higher than ACSR

Conductors). Additionally, AL-59 alloy conductors have 9 per cent better 'strength to weight

ratio' and 8 per cent lower sag compared with ACSR conductors which enables effective

optimization of tower designs and future proofing of the grid. In view of development of new

power transmission and distribution grids by global power incumbents, AL-59 alloy

conductors would have a special significance while designing transmission line networks, as

the properties of these conductors enable superior power evacuation while optimizing the cost

of the entire grid.

Chemical composition : Mark Chemical composition [ % ]

AI59Fe Si Cu Mn Mg Cr Zn B Ti+V Al

0,40 0,1 0,35 0,01 0,2 0,01 0,05 0,05 0,02 99,2

Permissible diameter deviation : +/- 5% for all diameters,

Rod ovalness : +/- 3% for all diameters

Mechanical and electrical features:

Tensile strength Rm ≥170 MPa

Elongation A100: ≥ 9 %

Resistivity ≤28,6 nm

Conductivity w % IACS ~59,4

Mechanical and electrical properties measurements made not less then 3 days after

quenching.

Measurements of rod electrical properties should be made at 20o C.





APPLICATION OF AL-59 ALLOY CONDUCTORSAl-59 Alloy Conductors are used in power transmission and distribution lines for a wide

voltage range - low voltage to Ultra high Voltage.

COMPLIANCE WITH STANDARDS

AL-59 alloy conductor complies with the standard SS4240814 and AL-59 alloy wires

complies with standard SS4240813 that specifies the limits for conductivity, strength and

creep irrespective of the chemical composition which is not discussed in this standard. Other

properties are similar to conventional AAAC conductors.

REFERENCE OF USE OF AL-59 ALLOY CONDUCTORS

Al-59 Alloy Conductors have been used extensively by Swedish Electricity, Swedish

Railways and Norway Electricity.

MATERIAL PROPERTIES

Size of the Conductor AL-59 conductors range from AL-59 31 sq-mm (7/2.38 mm) to AL-

59 910 sq-mm (61/4.36 mm).

Strength of the wire

For diameter less than 3.5 mm: 250 MPA

For diameter less than 4 mm: 240 MPA

For diameter less than 4.5 mm: 230 MPA

Resistivity of the wire

Individual resistivity: 29.30 nJm

Average resistivity: 29.08 nJm

Creep of the conductor

Maximum conductor Creep at 23oC at 40 % of rated tensile strength and 1500 hours are as

Follows

7 strands: 350 mm/Km 19 and 37 strands: 400 mm/Km

61 strands: 450 mm/Km


Fig. 4 AL 59 Conductors


COMPARISION WITH CONVENTIONAL ACSR AND AAACThe comparison is based on the current carrying capacity, strength of the conductor and sag.

The comparison for transmission as well as for the distribution is as detailed below:

Table 1 - Comparison of various Transmission conductors



Comparison of 7 strand Distribution conductors

Table 1 - Comparison of 7 strand Distribution conductors



Comparison of AAAC Weasel, ACSR Weasel and AL-59 conductors.

All Aluminium Alloy Conductors (AAAC)This conductor is made from aluminium-magnesium-silicon

alloy of high electrical conductivity containing enough

magnesium silicide to give it better mechanical properties after

treatment. These conductors are generally made out of

aluminium alloy 6201. AAAC CONDUCTOR has a better

corrosion resistance and better strength to weight ratio and

improved electrical conductivity than ACSR CONDUCTOR on

equal diameter basis.

AAC conductor is made from aluminum-magnesium-silicon alloy of high electrical

conductivity containing magnesium (0.6-0.9%) & silicon (0.5-0.9%) to give it better

mechanical properties after treatment. AAC conductors are generally made out of

aluminum alloy 6201 (minimum conductivity is 54%). AAC conductor has a better

corrosion resistance and better strength to weight ratio and improved electrical


Graph. 1 Comparison of AAAC Weasel, ACSR Weasel and AL-59 conductors


conductivity than ACSR conductor on equal diameter basis.

Key Benefits:

High tensile strength as compared to AAC conductor.

Higher conductivity as compared to ACSR conductor.

Better corrosion resistance than ACSR conductor.

Physical contents of alluminium alloy :

Density - 2.70 kgm/dm3 at 20°C

Coefficient of Linear Expansion - 23 x 10-6 / °C

Resistivity - 0.0326 Ohms mm2/m at 20°C

Constant Mass Temperature Coefficient (a) - 0.00360/ °C

Material - Heat treated Al. Mg. Si. Alloy

Comparison of AAAC 61/4.26, ACSR Bersimis and AL-59 910 sq.mm conductors

ACSR conductors consist of a solid or stranded steel core

surrounded by strands of aluminum (E.C. GRADE). ACSR

conductors are available in a wide range of steel, containing

carbon from 0.5% to 0.85 %. The higher strength ACSR

conductors are used for river crossings, overhead ground wires,

installations involving extra long spans etc. Against any given

resistance of conductor, ACSR may be manufactured for having

a wide range of tensile strength as per the requirement.

The principal advantage of these conductors are high tensile strength so that they are used

for longer spans with less supports. Due to the greater diameter of ACSR conductors a

much higher corona limit can be obtained causing big advantages on high as well as extra

high voltage overhead lines.


Graph. 2 Comparison of AAAC 61/4.26, ACSR Bersimis

and AL-59 910 sq.mm conductors


Comparison of AAAC Moose, ACSR Moose and AL-59 conductors

Aluminum Conductor Steel

Reinforced (or ACSR) cable is

a specific type of high-

capacity, high-strength

stranded cable used in overhead

power lines. The outer strands

are aluminum, chosen for its

excellent conductivity, low

weight, and low cost. The

center strand is of steel for the

strength required to support the weight without stretching the aluminum due to its ductility.

ACSR cables are available in several specific sizes, with multiple center steel wires and

correspondingly larger quantities of aluminum conductors. For example, an ACSR cable with

72 aluminum conductors that requires a core of 7 steel conductors will be called 72/7 ACSR

cable.[1] It has a very high tensile strength and it is used to reduce skin effect which is

predominant in AC supply applications

Even though strength of the AL-59 conductor is less compared to conventional AAAC, AL- 9

is strung at the same tension as like conventional AAAC. The Important factor for choosing

tension from the vibrating point of view is tension divided by the conductor mass. This value

is independent of Ultimate tensile strength


Graph.3 Comparison of AAAC Moose, ACSR Moose and AL-59 conductors

http://en.wikipedia.org/wiki/Alternating_current

http://en.wikipedia.org/wiki/Ductility

http://en.wikipedia.org/wiki/Steel

http://en.wikipedia.org/wiki/Aluminum

http://en.wikipedia.org/wiki/Overhead_powerline

http://en.wikipedia.org/wiki/Overhead_powerline


ADVANTAGES OVER ACSR AND AAAC

Higher current carrying capacity with lesser cross sectional area.

Higher power transfer capacity with lesser cross sectional area.

Commercial benefits due to lower power loss and higher power transfer capacity

Longer life

Lower power losses

Thermal stability

Higher ampacity



CONCLUSION

Power for all by the year 2012 is the vision of the Ministry of Power, Government of India.

The Government of India’s Transmission Perspective Plan focuses on the creation of a

‘National Grid’ in a phased manner by adding over 60,000 km of Transmission Network by

2012. Such an integrated grid is envisaged to evacuate additional 1, 00,000 MW by the year

2012 and carry 60% of the power generated in the country. The existing inter-regional power

transfer capacity is 9,000 MW, which is to be further enhanced to 30,000 MW by 2012

through creation of “Transmission Super Highways”. On a global level, ABS Research, UK

reports that the global market for power transmission conductors was valued at about

US$12.3 Billion in 2006 and has a CAGR of 7% from 2004 through 2006. ABS Research

also anticipates a stable demand growth in the global market from 2007 through 2010 at a

CAGR of about 7%. In view of development of new power transmission and distribution

grids by global power incumbents, Al-59 Alloy Conductors would have a special significance

while designing transmission line networks, as the properties of these conductors enable

superior power evacuation while optimizing the cost of the entire grid.



REFERANCES

Wikipedia- online encyclopaedia.

Sterlite ®. Sterlite is a registered trademark of Sterlite Technologies Limited -

www.sterlitetechnologies.com

New range of special alloy conductors – Advantages over ACSR & AAAC

conductors

Author G L Prasad

www.midalcable.com


F report

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