Lecture 10 Conductor Types

Lecture 9

Copper:◦ it is an excellent conductor◦ Very popular ◦ Not affected significantly by weather◦ It is durable

Aluminum:◦ Good conductor◦ Not as durable as copper◦ Cost is less◦ Less weight than copper◦ Rust resistant

Conductors (Continued)

Steel:◦ Poor conductor compared to copper and aluminum.

◦ It is very strong◦ To increase the tensile strength steel strands are used in aluminum conductors.

Conductors

Most common power line conductors are solid, stranded and aluminum conductor steel-reinforcced (ACSR).

Solid Conductors: smaller and stronger than stranded conductors. They are difficult to bend and get damaged easily. They are made of one solid wire.

Conductor Types

The figures below show solid conductors

Solid Conductors

http://workmanship.nasa.gov/lib/insp/2%20books/links/sections/101%20General%20Requirements.html

http://www.mcmelectronics.com/product/JSC-WIRE---CABLE-411831A-Y-500R-/24-9730

Three or more strands of conductor material is twisted to form a single conductor.

They can carry high currents and are more flexible than solid conductors.

The figure below shows a stranded conductor

Stranded Conductors

http://www.acsrconductors.com/all-aluminium-conductors.html

To add strength to aluminum conductors steel strands are used in the core.

These conductors are used for long span distances

The figure below shows ACSR conductors

Aluminum Conductor Steel- Reinforced

http://www.mohtacables.com/conductors.php

http://skm-systems.blogspot.com/2010/12/ac-transmission-lines.html

Question 1:Write the applications for the three conductor

types discussed above. Question 2:Write the advantages and disadvantages for the

three conductor types discussed above

Home Work 4

Two conductor sizes are used in electrical systems: a). American Wire Gauge b). Circular Mils

American Wire Gauge(AWG): ◦ Old standard ◦ Used for smaller conductors◦ As the conductors get larger the numbers get smaller

Circular Mils: ◦ Conductors greater than AWG 4/0 are measured in circular mils (cmils)

Conductor size

◦ One circular mil is equal to the area of a circle having a 0.001 inch (1 mil) diameter.

◦ Figure below shows a magnified picture of a conductor which has 55 c mils.

◦ In actual size a conductor of 55 circular mills is 4 times smaller than a full stop.

◦ Therefore conductors sized in circular mils are stated in thousands of circular mils.

Conductor size

Question 3:Table 3-1 pg 53 of your textbook shows conductor sizes in AWG, cmils. Try to understand the table e.g. in row one of the table AWG size is given as 4,copper equivalent is given as 6, ratio is given as 7/1 etc… figure

out of a relationship exists between these columns. If a relationship exists find and explain that. If no relationship exists then comment on you findings.

Home Work 4 (continued)

Current carrying conductors of metal can be insulated or non insulated when in use.

Bare wires use insulators for separating them from grounded structures.

Question 4: Find example for the second bullet. Also List applications of bare wires.

Insulated conductors use plastic, rubber or other jacketing materials for electrical isolation.

Question 5: Find and list the applications of insulated conductors.

Insulation and Outer Covers

Question 1: Table 3-2 pg 54 of your textbook shows voltage class, voltage category and system

voltages for North America. Find the above

three for Pakistan.

Home Work 5

Read Your self pg 55-56 of your textbook

Transmission Line Design Parameters

Three to ten times costlier than over head transmission lines because of right of way requirements, material cost, obstacles etc…

Usually used near airports or urban areas where overhead transmission is not possible.

Underground Transmission

Question 2:List advantages and disadvantages of overhead

transmission lines Question 3:List advantages and disadvantages of underground transmission lines. Question 4:List applications of overhead and underground

transmission lines.

Home Work 5 (Continued)

Method of submission:

Homework 4 is due next week on 12th October 2011. Assignments submitted after class time would be considered as late, and no late assignments would be entertained.

Homework 5 is due the week after that on 19th October 2011. Assignments submitted after class time would be considered as late, and no late assignments would be entertained.

Due Dates