Cable Sizing Calculations front sheet

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SOFCON-STANLEY APPROVED

KINGDOM OF SAUDI ARABIA

RC APPROVED

‫المملكة العربية السعودية‬

ROYAL COMMISSION FOR JUBAIL AND YANBU

‫الهيئة الملكية للجبيل وينبع‬

DIRECTORATE GENERAL FOR

‫الدارة العامة لمشروع الجبيل‬

JUBAIL PROJECT

‫مدينة الجبيل الصناعية‬

JUBAIL INDUSTRIAL CITY

T06-202 :‫عمل رقم‬

JOB No. 202-T06 DESIGN OF POWER AND TELECOMMUNICATION SYSTEM FOR STAGE 1 OF JUBAIL 2 FACILITY NO. 1-08-071

071-08-1 : ‫رقم المنشأة‬

CONTRACT NO. 071-C11

C11-071 :‫رقم العقد‬

SUBSTATION FOR STAGE 1 OF JUBAIL 2

230kV CABLE SIZING CALCULATIONS

SCALE:

None

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DESIGN OF POWER AND TELECOMMUNICATION SYSTEM FOR STAGE 1 OF JUBAIL 2

SOFCON / STANLEY Association Subject:

230kV CABLE SIZING CALCULATIONS

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CONTENTS

6. Results and Conclusions:............................................................................................................6 i) The proposed cable size of 2000mm2 XLPE copper between GIS and 400MVA transformers is adequate..............................................................................................................6 ii) The proposed cable size of 630mm2 XLPE copper between GIS and 133MVA transformers is adequate..............................................................................................................6

Pr Prepared: AB

Checked : SS

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Approved : RD

Date and Time: 3/21/20110:58 a3/p3

DESIGN OF POWER AND TELECOMMUNICATION SYSTEM FOR STAGE 1 OF JUBAIL 2

SOFCON / STANLEY Association 230kV CABLE SIZING CALCULATIONS

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Purpose and Scope: This document deals with sizing calculations for the 13.8kV cables proposed between pad transformers to mounted switches and from pad mounted switches to existing substation SS/6F. It may be noted that as per PTS, the CONTRACTOR shall obtain this calculation from the cable manufacturer but now a rough calculation is done for the purpose of selecting the tentative size of the cable.

2.

Design Input: • Design Parameters: The following design parameters are considered. Nominal Voltage System short circuit current for 1 sec. Maximum conductor short circuit temperature Maximum permissible continuous conductor temperature

3.

: : : :

13.8 kV 25 kA 250°C 90°C

Assumptions: Maximum ambient temperature of 40°C is assumed inside the duct banks

4.

Methodology: This calculation is carried out in line with SEC-EOA standards SES-P-104.03.

5.

Calculations:

5.1

Ampacity Calculations for 300mm2 XLPE Copper Cable Table 03-5(6A) of SES-P-119.03, 5.1.1

Cable Ampacity in Air Though this is manufacturer specific, a typical value of 1890A is considered from Table 03-5(6A) given in SES-P-104.03. Also though this value pertains to oil filled cable, the same is considered for XLPE cable, which results in safer design, since XLPE insulated cables typically have more ampacity than oil filled cables.

5.1.2

Derating Factors To this value of 1890A, derating factors have to be applied based on the proposed laying conditions. Since in our case cable is not buried, the following typical derating factors given in Section 4.9.4.3 of the above-mentioned SES are considered.

Pr Prepared: AB

Checked : SS

/opt/scribd/conversion/tmp/scratch6078/53994886.doc

Approved : RD

Date and Time: 3/21/20110:58 a3/p3

DESIGN OF POWER AND TELECOMMUNICATION SYSTEM FOR STAGE 1 OF JUBAIL 2

SOFCON / STANLEY Association 230kV CABLE SIZING CALCULATIONS

Subject:

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Derating Factor for Variation in Air Temperature (F21) In our case, the cable is partially laid in Cable Cellar which is partially air conditioned and the other portion is laid in Cable Trench. Since the cable trench is not air conditioned, the ambient temperature is considered as 40°C. But since the air is not circulated, the heat generated by the cables increases the temperature by a few degrees. For safe design, this increase is considered as 10°C and hence derating factor of 0.89 for 50°C air temperature [from Table 03-5(21) of the above SES] is considered.

5.1.2.2

Grays Derating Factor for Cables Installed above Ground (F22) In each cable trench, three single core cables are laid with a spacing of 400mm. This spacing is more than twice the diameter of the cable and for safer design, this factor is taken as 0.95 from Table 03-5(22) of the above-mentioned SES.

5.1.3 Derated Ampacity This is the product of Ampacity in air multiplied by Derating factors. In other words, Derating ampacity

= = =

1890 x F21 x F22 1890 x 0.89 x 0.95 1598 A

Since this is greater than the 1339A required as per Section 4.03A.1 of PTS1135, the cable of 2000mm2 size selected is adequate. 5.2

Ampacity Calculations for 630mm2 XLPE Copper Cable Table 03-5(6A) of SES-P-119.03, 5.2.1

Cable Ampacity in Air Though this is manufacturer specific, a typical value of 1890A is considered from Table 03-5(6A) given in SES-P-104.03. Also though this value pertains to oil filled cable, the same is considered for XLPE cable, which results in safer design, since XLPE insulated cables typically have more ampacity than oil filled cables.

5.2.2

Pr Prepared: AB

Derating Factors

Checked : SS

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Approved : RD

Date and Time: 3/21/20110:58 a3/p3

DESIGN OF POWER AND TELECOMMUNICATION SYSTEM FOR STAGE 1 OF JUBAIL 2

SOFCON / STANLEY Association 230kV CABLE SIZING CALCULATIONS

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To this value of 1890A, derating factors have to be applied based on the proposed laying conditions. Since in our case cable is not buried, the following typical derating factors given in Section 4.9.4.3 of the above-mentioned SES are considered. 5.2.2.1

Derating Factor for Variation in Air Temperature (F21) In our case, the cable is partially laid in Cable Cellar which is partially air conditioned and the other portion is laid in Cable Trench. Since the cable trench is not air conditioned, the ambient temperature is considered as 40°C. But since the air is not circulated, the heat generated by the cables increases the temperature by a few degrees. For safe design, this increase is considered as 10°C and hence derating factor of 0.89 for 50°C air temperature [from Table 03-5(21) of the above SES] is considered.

5.2.2.2

Grays Derating Factor for Cables Installed above Ground (F22) In each cable trench, three single core cables are laid with a spacing of 400mm. This spacing is more than twice the diameter of the cable and for safer design, this factor is taken as 0.95 from Table 03-5(22) of the above-mentioned SES.

5.2.3

Derated Ampacity This is the product of Ampacity in air multiplied by Derating factors. In other words, Derating ampacity

= = =

1890 x F21 x F22 1890 x 0.89 x 0.95 1598 A

Since this is greater than the 1339A required as per Section 4.03A.1 of PTS1135, the cable of 2000mm2 size selected is adequate. 5.2.4

Short Circuit Current Rating for Copper Conductor Nominal conductor area in mm2

=

2000 mm2

Short circuit time in seconds

=

1 second

Maximum allowable short circuit current

Pr Prepared: AB

Checked : SS

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Approved : RD

Date and Time: 3/21/20110:58 a3/p3

DESIGN OF POWER AND TELECOMMUNICATION SYSTEM FOR STAGE 1 OF JUBAIL 2

SOFCON / STANLEY Association 230kV CABLE SIZING CALCULATIONS

Subject:

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for XLPE, copper conductor

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142 × Area Time

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(from Section

4.9.6 of above SES) = =

142 × 2000 1

284 kA

Since this is higher than the required short circuit of 63kA, the offered conductor size is adequate. 6. 6.1

Results:

ii) 6.2

Results and Conclusions:

i) The proposed cable size of 2000mm2 XLPE copper between GIS and 400MVA transformers is adequate. The proposed cable size of 630mm2 XLPE copper between GIS and 133MVA transformers is adequate.

Conclusions: Based on the results of the calculations, it is concluded that the proposed conductor sizes for 230kV cables is adequate.

7.

References: SES-P-104.03 – Cable selection

8.

Attachments: Attachment-1

Pr Prepared: AB

Checked : SS

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Approved : RD

Date and Time: 3/21/20110:58 a3/p3