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Assumption University Thailand
EE4503Electrical Systems Design
Cable
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Assumption University Thailand
Topics
• Introduction to Cables
• Cables for low voltage
• Cables for high voltage
• Cable selection
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Assumption University Thailand
Cables
• Functionality
– Conduct electrical power from one point to other
• Components
– Conductor
– Insulator (optional)
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Assumption University Thailand
Cables - Conductor
• Physical
– Solid
– Strand: flexible, reduce skin effect
• Material
– Copper
– Aluminum
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Assumption University Thailand
Cables - Conductor
http://www.cedengineering.com/upload/Electrical%20Conductors.pdf http://www.geindustrial.com/Newsletter/Aluminum_vs_Copper.pdf
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Assumption University Thailand
Cables - Insulator
• Prevent the physical contact: between two
cables, cable-to-ground
– Physical durable e.g. impact, heat
– Chemical durable, e.g. erosion
• Commonly used
– Polyvinyl Chloride (PVC)
– Cross linked Polyethylene (XLPE)6
Assumption University Thailand
Cables - Insulator
http://www.gridcables.com/power-cable.html
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Assumption University Thailand
Cables for High Voltage
• Withstand the high voltage: insulator (if any)
need to be good.
• Long distance transmission: Cable cost &
Installation cost (e.g. electricity pole)
• Two main types
– Bare Wires (reduce cost)
– Insulated Wires8
Assumption University Thailand
High Voltage CablesBare Wires
• Made of Aluminum for lower cost
• Transmission system (not distribution system
for safety): Reduce usage: animals, accident, etc.
• AAC: All Aluminum Cable
• AAAC: All Aluminum Alloy Cable
• ACSR: Aluminum Conductor Steel Reinforced9
Assumption University Thailand
High Voltage CablesBare Wires
• AAC: Basic type, for shorter span
• AAAC: Improve the property of Aluminum by making it as an alloy stronger, larger span, corrosion resistance (e.g. sea)
• ACSR: Insert the steel in the core to have more tension.
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Assumption University Thailand
High Voltage CablesInsulated Wires
• For safety and prevent interruption
• PIC: Partial Insulated Cable
• SAC: Space Aerial Cable
• XLPE: Cross-linked
Polyethylenehttp://www.huffingtonpost.co.uk/2012/03/26/northamptonshire-fire-crew-hot-air-balloonist_n_1378971.html
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Assumption University Thailand
High Voltage CablesInsulated Wires - PIC
http://www.thaiyazaki-electricwire.co.th/products/pdf/edit_pdf/hvmvpc/33kv_oc.pdf
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Assumption University Thailand
High Voltage CablesInsulated Wires - SAC
http://www.thaiyazaki-electricwire.co.th/products/pdf/edit_pdf/hvmvpc/35kv_cc.pdf
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Assumption University Thailand
High Voltage CablesInsulated Wires - XLPE
http://www.thaiyazaki-electricwire.co.th/products/pdf/edit_pdf/hvmvpc/115kv_ce.pdf
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Assumption University Thailand
Cables for Low Voltage
• Below 750V
• Conductor: Aluminum or Copper
• Insulator: PVC or XLPE
• Number of Conductor: 1 or many
• Special Type to suite the need: Fire Retardent
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Assumption University Thailand
Cables for Low Voltage(see pdf)
• PVC
– NAY (aluminum)
– THW
– VAF
– VCT
– NYY (double shealth)
• XLPE
– CV
• MI
• Fire Safety Cable
– Flame Retardant
– Fire Resistant16
Assumption University Thailand
Cables for Low VoltageFire Resistant Cable
• Flame Retardancy
• Flame Propagation
• Acid and Corrosive Gas Emission
• Smoke Emission
• Fire Resistance (Circuit Integrity)
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Assumption University Thailand
Cables for Low VoltageFire Resistant Cable
• Fire Alarm System
• Building Automation System
• Emergency Lighting System
• Public Address System
• Standby Power System
• Computer Network System
• Closed Circuit TV System
• Elevators and Escalators System
• Fire Pumps and Pressurized Stairs
• Etc.
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Assumption University Thailand
Assignments
• Take pictures of the cable that you can see and classify the types of those cables.
• Take pictures of the name-plates
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Assumption University Thailand
Cable Selection
• Usage: Table 5-16 (EIT Standard 2001-51) for low
voltage cable
• Rated Voltage: 300V or 750V
• Rated Current
• Multiple Conductors
• Voltage Drop20
Assumption University Thailand
Cable Selection – Rated Current
• Size of Conductor
• Type of Insulator
• Ambient Temperature
• Installation Conditions:
– Calculation: BCC - Technical_data_Cable
– Table: BCC - InstallationGuide, AS_NZS_3008.1.1_2009
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Assumption University Thailand
Cable Selection – Rated CurrentInstallation Conditions (3.1)
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Rated CurrentInstallation Conditions (3.1t)
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Rated CurrentInstallation Conditions (3.2)
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Rated CurrentInstallation Conditions (3.2t)
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Rated CurrentInstallation Conditions (3.3)
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Rated CurrentInstallation Conditions (3.3t)
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Rated CurrentNumber of Cables in a Conduit
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Multiple Conductors
• To increase the rated current
Handout: BCC - Installation Guide.pdf
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Assumption University Thailand
Cable Selection – Multiple Conductors
• Only for cable from 50 sq.mm. and up
• Same type of cables
• Same length
• Same wiring method
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Assumption University Thailand
Cable Selection – Voltage Drop
• Voltage drop due to the impedance of the cable
• NEC
– Main incoming to load: no more than 5%
– Feeder: no more than 2%
– Branch Circuit: no more than 3%
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Assumption University Thailand
Cable Selection – Voltage Drop
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Zcable
Zload
220 V (AC)
Assumption University Thailand
Cable Selection – Voltage Drop
• Load: is from the consumption and power factor: or
• Cable: is from the table ( and )
– depends on the wiring configurations.
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Assumption University Thailand
Cable Selection – Voltage DropCalculation
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• Use the normal voltage divider in the calculation.
– =
– =
– ????
Assumption University Thailand
Cable Selection – Voltage DropCalculation
http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pour-visualisation_basse_def.pdf
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Assumption University Thailand
Cable Selection – Rated CurrentCalculation
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http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pour-visualisation_basse_def.pdf
Assumption University Thailand
Equivalent CircuitsImpedance: table for PVC cables
and
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Size () Resistance()
Reactance()
2.5 7.400 0.155
4 4.625 0.141
6 3.083 0.131
10 1.850 0.121
16 1.156 0.113
25 0.740 0.107
35 0.529 0.103
50 0.370 0.100
Electrical Systems Design: ประสิ�ทธิ์�� พิ�ทยพิ�ฒน์�
Size () Resistance()
Reactance()
70 0.264 0.097
95 0.195 0.096
120 0.154 0.094
150 0.123 0.092
185 0.100 0.091
240 0.077 0.090
300 0.062 0.089
400 0.051 0.088
Assumption University Thailand
Cable Selection – Rated CurrentFrom Table
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http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pour-visualisation_basse_def.pdf
Assumption University Thailand
Cable Selection – General Rules
• 20% to 25% factor.
• Using current or VA (not power).
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Assumption University Thailand
Cable Selection – Examples
• Water Heater 6kW
– in Air or in Metal Conduit
• Microwave 2,300VA
• Industrial Heater 40kW, 400V 3phase
– 40oC or 50oC
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Assumption University Thailand
Cable Selection – Examples
• Motor 37kW, 400V, In=72A
– DOL & Star-Delta
• Motor 60kW, 400V, pf.=0.8
• Room
– receptacles 2.5kVA
– lighting 500VA41
Assumption University Thailand
Handout
• BCC - Installation Guide
• HELUKABEL - Installation Operating Conditions
• AS_NZS_3008.1.1_2009
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Assumption University Thailand
• Electrical Systems Design: ประสิ�ทธิ์�� พิ�ทยพิ�ฒน์�• Thai Electrical Code 2002: EIT Standard 2001-51
• http://www.bangkokcable.com
• http://www.thaiyazaki-electricwire.co.th
• Electrical Installation Guide 2010: schneider-electric
Reference
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