Calculation of Cross Sectional Area of single core power cable

8/10/2019 Calculation of Cross Sectional Area of single core power cable

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Post Lab Report # 1

Electrical Power Distribution & Utilization (EE-357)

Zain Alam

EE-072 Page 1 of 3

1. Introduction:

Power cables used for electrical distribution have different area of core (multiple strands)

and number of conductors, both the things varies with the application Our objective was tounderstand the construction of power cables and calculation of cross sectional area of a single core.

1.1 Construction:

Power cable is an assembly of two or more stranded copper or aluminum conductors1, twisted

together2 and held together with an overallsheath. The assembly is used for transmission

ofelectrical power. Cables consist of three major components: conductors, insulation, and

protective jacket (includes serving, bedding, armouring). The makeup of individual cables varies

according to application. The construction and type of materials to be used are determined by three

main factors:

Working voltage, determining the thickness

of the insulation.

Current-carrying capacity, determining the

cross-sectional size of the conductors.

Environmental conditionssuch as

temperature, water, chemical or sunlight

exposure, and mechanical impact,

determining the form and composition of the

outer cable jacket.

Power cables are classified based upon the rating of

insulation. In KESC, for most application PVC & XLPE are used because of economical reasons3. In

three core cables it is necessary to fill the interstial spaces with jute, paper or polyethene bag for

two reasons.

Allowing the formulation of a cable core that is circular in shape.

Preventing an internal passage within the cable from moisture or flammable gases, when

used in hazardous areas.

1.2 International Cable Manufacturing Standards:

In Pakistan, following standards are generally employed:4

LV Cables:

BS: 6346

BS: 5467

Figure 1.1: Parts of Power Cable
http://en.wikipedia.org/wiki/Conductor_(material)http://en.wikipedia.org/wiki/Conductor_(material)http://en.wikipedia.org/wiki/Sheathhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Sheathhttp://en.wikipedia.org/wiki/Conductor_(material)


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Post Lab Report # 1


Zain Alam

EE-072 Page 2 of 3

IEC: 60502-1

MV Cables:

IEC: 60502-1

2. Theory/calculation:

Calculating the area of core is essential for the application of power cables, such as for high

current application the area must be sufficient to reduce the power loss, also it depends on the type

of material, as copper conductor uses lesser area as compare to aluminium in same amount of

current application.. The proper sizing of power cable is important to ensure that the cable can:

Operate continuously under full load without being damaged.

Withstand the worst short circuits currents flowing through the cable.

Provide the load with a suitable voltage (and avoid excessive voltage drops).

For calculating the area of the core, we have to calculate the diameter of a single strand

first. For this purpose Screw gauge or Vernier Caliper will be used.

Area of Conductor= * (D/2)2

AndD= (1+2N) * d

Where,

Dis diameter of core, N is the no. of strands anddis the diameter of single strand.

Serial No. M.S.R C.S.R FP=C.S.R*LC T.R=M.S.R+FP Mean

(mm) (div) (mm) (mm) (mm)

1 0.325 13 0.13 0.338

2 0.325 12 0.12 0.337 0.338

3 0.325 14 0.14 0.339

Table 2.1: Observation Table for Conductor Diameter

Least Count of screw guage = 0.01mm.

The diameter of a single strand of 3 core cable is found to be d=0.338mm.

The number strands found by us for the given power cable are 19.

Therefore,

D= {1+ (2*19)}*0.338

D=13.182 mm.

Area of Conductor = * (D/2)2

Area of Conductor = * (13.182/2)2


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Post Lab Report # 1


Zain Alam

EE-072 Page 3 of 3

Area of Conductor = 136.5137mm2.

3. Results:

The area of core is found to be 137 mm2.

4. Discussion:

From our observation of different power cables in the lab, we analyzed that the number of

strands varies from cable to cable, different no. of conductors and variations in insulation thickness.

It has been cleared that these factors varies with the type or the nature of application.

The area of conductor of the observed cable was found to be 137 mm2. The copper core

having this much of area is likely to be applicable in low tension (LT) distributions

5

. For HTdistributions in KESC, conductors having cross sectional area of 300 mm

2are used.

5. Conclusion:

The area of conductor of the observed cable was found to be 137 mm2. The copper core

having this much of area is likely to be applicable in low tension (LT) distributions6. For HT

distributions in KESC, conductors having cross sectional area of 300 mm2 are used. If this type of

power cable is use in high tension (HT) then there is higher power losses, and it is not suitablefor

industrial consumers.

References:

http://www.openelectrical.org/wiki/index.php?title=Cable_Sizing_Calculation

http://www.ke.com.pk/

http://en.wikipedia.org/wiki/High-voltage_cable

http://www.pakistancables.com/voltage.html

Figure Captions:

Figure 1.1 taken fromwww.tradekorea.com
http://www.openelectrical.org/wiki/index.php?title=Cable_Sizing_Calculationhttp://www.ke.com.pk/http://en.wikipedia.org/wiki/High-voltage_cablehttp://www.tradekorea.com/product-detail/P00261229/18_30KV_CU_XLPE_PVC_LEAD_PVC_SWA_PVC_POWER_CABLES.htmlhttp://www.tradekorea.com/product-detail/P00261229/18_30KV_CU_XLPE_PVC_LEAD_PVC_SWA_PVC_POWER_CABLES.htmlhttp://en.wikipedia.org/wiki/High-voltage_cablehttp://www.ke.com.pk/http://www.openelectrical.org/wiki/index.php?title=Cable_Sizing_Calculation

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Calculation of Cross Sectional Area of single core power cable