yuleba name and the locations of roma, surat, miles and chinchilla mentioned

8/10/2019 Yuleba Name and the Locations of Roma, Surat, Miles and Chinchilla Mentioned

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YULEBA NAME AND THE

LOCATIONS OF ROMA, SURAT,

MILES AND CHINCHILLA

MENTIONED


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Thermal sand is widely used throught the power industry to

improve underground electrical cable performance. An

electrical cable primarily made up of two elements theconductor and the insulator, the limiting factor on a power

cable capacity is the temperature that the insulation can

withstand and the more power or current that is flowing

through the conductor the more heat is generated by the

cable.


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Different insulation materials are available PVC is rated to 60

deg C and XLPE a cross linked poly ethylene is rated at 90

deg C meaning that for the same size conductor the current

carry capacity of the cable can be increased by as much as


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Other insulating materials based on ceramic materials are

used in special applications but these types of insulations

are very expensive and reach the point where there cost is

the same as the conductor meaning it easier and cheaper to

increase the size of the conductor.


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Burying the cable in the ground increases the cable capacity,

the ground act as a heat sink taking heat away from the

insulation and reducing the cable temperature. Thermal sand

is a way of increasing this thermal heat transfer.


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Thermal sand is now widely used when installing

underground cables. The thermal sand is rated or tested to

provide a known heat transfer efficiency.


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The cable and the thermal sand are installed so that the

thermal sand is in direct contact with the cable. The thermal

sands high heat transfer efficiency ensures the heat

generated by the cable is transfered from the cable through

the thermal sand to the surounding earth.


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Thermal sand is specified to a thermal resisitivity which is

measured in deg K m/W or C-cm/W and typically the thermal

sand may need to meet a required standard for example

thermal resistivity shall be less than or equal to 0.9 K m/W


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The thermal sand becomes the connection between the cable

and the general mass of the earth.All the heat generated by

an underground power cable must be dissipated through the

soil. This is quantified by the soil thermal resistivity (or

thermal rho, C-cm/W), which can vary from 30 to 500C-cm/W. Electrical engineers understand the performance of

the cable quite well, but to most, the soil behavior is a

mystery, usually handled by using a thermal backfill with a

supposedly safe thermal rho.


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The ability of the surrounding soil to transfer the heat

determines whether an operating cable remains cool or

overheats. Improving the external thermal environment and

accurately defining the soil and backfill thermal rhocommonly results in a 10% to 15% increase in cable

ampacity, with 30% improvements noted in some cases.


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Compacted granular backfills can have good thermal

properties. Since most of the heat conduction is through the

soil mineral particles and their contacts, one must ensure a

high-density soil mixture to maximize these contacts. A well-

graded sand to fine gravel can be a good thermal backfill

when compacted to its maximum density as determined by a

laboratory standard Proctor test (ASTM D698).


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The total cost of a compacted backfill must include material

and transportation costs, as well as installation labor and

quality-assurance costs. Yuleba Minerals makes a thermal

sand which has been used for projects in and around Roma,

Chinchilla and the Surat basin.


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The one often-neglected factor about compacted backfills is

the need for quality assurance during installation. If the

gradation of the backfill is not correct (sieve analysis ASTM

D422), or it is not at the optimum moisture content (ASTM

D698), or not enough compaction effort is applied, or thebackfill lifts are too thick, then the maximum density will not

be achieved and the thermal capability degraded.


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Gas Power projects in the Surat basin have been the catalyst

for Yuleba Minerals developing and testing a thermal sand for

use in underground cable installation.


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To know more information, visit us

http://www.yulebaminerals.com.au/
http://www.yulebaminerals.com.au/http://www.yulebaminerals.com.au/

yuleba name and the locations of roma, surat, miles and chinchilla mentioned

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