Cable

Assumption University

Thailand

EE4503

Electrical Systems Design

Cable

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Thailand

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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(see pdf)

• PVC • XLPE

–

NAY

(aluminum)

–

THW

–

VAF

–

VCT

–

NYY (double shealth)

–

CV

•

MI

•

Fire Safety Cable

–

Flame Retardant

–

Fire Resistant

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Fire Resistant Cable

• Flame Retardancy

• Flame Propagation

• Acid and Corrosive Gas Emission

• Smoke Emission

• Fire Resistance (Circuit Integrity)

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Fire Resistant Cable

•

Fire Alarm System

•

Computer Network System

•

•

Building Automation

System

•

Closed Circuit TV System

•

Emergency Lighting System

•

Elevators and Escalators

System

•

Public Address System

Standby Power System

•

Fire Pumps and Pressurized

Stairs

•

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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Installation Conditions (3.1)

Handout: BCC - Installation Guide.pdf

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Installation Conditions (3.1t)


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Number of Cables in a Conduit


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Cable Selection – Multiple Conductors

•

To increase the rated current


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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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Z cable

220 V (AC)

Z load

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•

Load: 𝑍 𝑙 is from the consumption and power factor: 𝑝𝑓 =

𝑅 𝑙

𝑍 𝑙 or cos −1 𝑝𝑓 =

𝑅 𝑙

𝑍 𝑙

• Cable: 𝑍 𝑐 is from the table ( 𝑅 𝑐 and 𝑋 𝑐

)

– 𝑋 𝑐 depends on the wiring configurations.

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Calculation

• Use the normal voltage divider in the calculation.

– 𝐸 𝑠𝑜𝑢𝑟𝑐𝑒

= 𝐸 𝑐

+𝐸 𝑙

– 𝐸 𝑠𝑜𝑢𝑟𝑐𝑒

= 𝐼 ∗ (𝑅 𝑐

+ 𝑗𝑋 𝑐

) +𝐸 𝑙

–

????

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Calculation http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pourvisualisation_basse_def.pdf

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Calculation http://www.east-med.schneider-electric.com/documents/electrical-distribution/en/shared/eig_guide2010/Doc-pourvisualisation_basse_def.pdf

36

10

16

25

35

50

2.5

4

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Equivalent Circuits

Impedance: table for PVC cables

𝑅 𝑐

= 𝑅 ∗ 𝐿 and 𝑋 𝑐

= 𝑋 ∗ 𝐿

Size

( 𝒎𝒎 𝟐

)

Resistance

( 𝒎𝛀 𝒎

)

7.400

4.625

3.083

1.850

1.156

0.740

0.529

0.370

Reactance

( 𝒎𝛀 𝒎

)

0.155

0.141

0.131

Size

( 𝒎𝒎 𝟐

70

95

120

)

0.121

0.113

0.107

0.103

150

185

240

300

0.100

400

Electrical Systems Design:

ประสิทธิ์ พิทยพัฒน์

Resistance

( 𝒎𝛀 𝒎

)

0.264

0.195

0.154

0.123

0.100

0.077

0.062

0.051

Reactance

( 𝒎𝛀 𝒎

)

0.097

0.096

0.094

0.092

0.091

0.090

0.089

0.088

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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

–

40 o C or 50 o C

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Cable Selection – Examples

•

Motor 37kW, 400V, I n

=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:

ประสิทธิ์ 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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Cable

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