Transcript Cable

Assumption University
Thailand
EE4503
Electrical Systems Design
Cable
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Assumption University
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Topics
• Introduction to Cables
• Cables for low voltage
• Cables for high voltage
• Cable selection
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Cables
• Functionality
– Conduct electrical power from one point to
other
• Components
– Conductor
– Insulator (optional)
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Cables - Conductor
• Physical
– Solid
– Strand: flexible, reduce skin effect
• Material
– Copper
– Aluminum
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Cables - Conductor
http://www.cedengineering.com/upload/Electrical%20Conductors.pdf
http://www.geindustrial.com/Newsletter/Aluminum_vs_Copper.pdf
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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)
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Cables - Insulator
http://www.gridcables.com/power-cable.html
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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 Wires
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High Voltage Cables
Bare 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 Reinforced
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High Voltage Cables
Bare 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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High Voltage Cables
Insulated Wires
• For safety and prevent
interruption
• PIC: Partial Insulated Cable
• SAC: Space Aerial Cable
• XLPE: Cross-linked
Polyethylene
http://www.huffingtonpost.co.uk/2012/03/26/northamptons
hire-fire-crew-hot-air-balloonist_n_1378971.html
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High Voltage Cables
Insulated Wires - PIC
http://www.thaiyazaki-electricwire.co.th/products/pdf/edit_pdf/hvmvpc/33kv_oc.pdf
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High Voltage Cables
Insulated Wires - SAC
http://www.thaiyazaki-electricwire.co.th/products/pdf/edit_pdf/hvmvpc/35kv_cc.pdf
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High Voltage Cables
Insulated Wires - XLPE
http://www.thaiyazaki-electricwire.co.th/products/pdf/edit_pdf/hvmvpc/115kv_ce.pdf
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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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Cables for Low Voltage
• PVC
(see pdf)
• XLPE
– NAY (aluminum)
– CV
– THW
• MI
– VAF
• Fire Safety Cable
– VCT
– Flame Retardant
– NYY (double shealth)
– Fire Resistant
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Cables for Low Voltage
Fire Resistant Cable
• Flame Retardancy
• Flame Propagation
• Acid and Corrosive Gas Emission
• Smoke Emission
• Fire Resistance (Circuit Integrity)
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Cables for Low Voltage
Fire Resistant Cable
• Fire Alarm System
• Computer Network System
• Building Automation
System
• Closed Circuit TV System
• Public Address System
• Fire Pumps and Pressurized
Stairs
• Elevators and Escalators
• Emergency Lighting System
System
• Standby Power System
• Etc.
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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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Cable Selection
• Usage: Table 5-16 (EIT Standard 2001-51) for low
voltage cable
• Rated Voltage: 300V or 750V
• Rated Current
• Multiple Conductors
• Voltage Drop
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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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Cable Selection – Rated Current
Installation Conditions (3.1)
Handout: BCC - Installation Guide.pdf
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Cable Selection – Rated Current
Installation Conditions (3.1t)
Handout: BCC - Installation Guide.pdf
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Cable Selection – Rated Current
Installation Conditions (3.2)
Handout: BCC - Installation Guide.pdf
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Cable Selection – Rated Current
Installation Conditions (3.2t)
Handout: BCC - Installation Guide.pdf
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Cable Selection – Rated Current
Installation Conditions (3.3)
Handout: BCC - Installation Guide.pdf
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Cable Selection – Rated Current
Installation Conditions (3.3t)
Handout: BCC - Installation Guide.pdf
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Cable Selection – Rated Current
Number of Cables in a Conduit
Handout: BCC - Installation Guide.pdf
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Cable Selection – Multiple Conductors
• To increase the rated current
Handout: BCC - Installation Guide.pdf
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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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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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Cable Selection – Voltage Drop
Zcable
220 V (AC)
Zload
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Cable Selection – Voltage Drop
• Load: 𝑍𝑙 is from the consumption and
power factor: 𝑝𝑓 =
𝑅𝑙
𝑍𝑙
or cos
−1
𝑝𝑓 =
𝑅𝑙
𝑍𝑙
• Cable: 𝑍𝑐 is from the table (𝑅𝑐 and 𝑋𝑐 )
– 𝑋𝑐 depends on the wiring configurations.
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Cable Selection – Voltage Drop
Calculation
• Use the normal voltage divider in the
calculation.
– 𝐸𝑠𝑜𝑢𝑟𝑐𝑒 =𝐸𝑐 +𝐸𝑙
– 𝐸𝑠𝑜𝑢𝑟𝑐𝑒 =𝐼 ∗ (𝑅𝑐 + 𝑗𝑋𝑐 ) +𝐸𝑙
– ????
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Cable Selection – Voltage Drop
Calculation
http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pourvisualisation_basse_def.pdf
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Cable Selection – Rated Current
Calculation
http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pourvisualisation_basse_def.pdf
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Equivalent Circuits
Impedance: table for PVC cables
𝑅𝑐 = 𝑅 ∗ 𝐿 and 𝑋𝑐 = 𝑋 ∗ 𝐿
Size
(𝒎𝒎𝟐 )
Resistance
𝒎𝛀
( )
Reactance
𝒎𝛀
( )
Size
(𝒎𝒎𝟐 )
Resistance
𝒎𝛀
( )
Reactance
𝒎𝛀
( )
2.5
7.400
0.155
70
0.264
0.097
4
4.625
0.141
95
0.195
0.096
6
3.083
0.131
120
0.154
0.094
10
1.850
0.121
150
0.123
0.092
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1.156
0.113
185
0.100
0.091
25
0.740
0.107
240
0.077
0.090
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0.529
0.103
300
0.062
0.089
50
0.370
0.100
400
0.051
0.088
𝒎
𝒎
𝒎
𝒎
Electrical Systems Design: ประสิ ทธิ ์ พิทยพัฒน์
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Cable Selection – Rated Current
From Table
http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pourvisualisation_basse_def.pdf
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Cable Selection – General Rules
• 20% to 25% factor.
• Using current or VA (not power).
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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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Cable Selection – Examples
• Motor 37kW, 400V, In=72A
– DOL & Star-Delta
• Motor 60kW, 400V, pf.=0.8
• Room
– receptacles 2.5kVA
– lighting 500VA
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Handout
• BCC - Installation Guide
• HELUKABEL - Installation Operating
Conditions
• AS_NZS_3008.1.1_2009
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Reference
• Electrical Systems Design: ประสิ ทธิ ์ พิทยพัฒน์
• Thai Electrical Code 2002: EIT Standard 2001-51
• http://www.bangkokcable.com
• http://www.thaiyazaki-electricwire.co.th
• Electrical Installation Guide 2010: schneider-electric
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