Easy Questions from a Newbie

Discussion in 'Homework Help' started by matttrix, Mar 6, 2009.

Mar 6, 2009
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Sorry this must be some easy questions but I am lost in this assignment.

Does insulation of a wire affect its resistance? Explain

List 4 factors used to select wire for a specified current rating?

What are the most common insulator used for extremely high voltages. Explain your answer with, at least, two points for each insulator. Hint: They can withstand much higher temperatures than rubber insulation. The first is in tape form and it would is wound around the conductor in layers. The second is infused with mineral oil.

2. thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
Insulation has resistance, but it doesn't change the resistance of the wire it is surrounding. The copper is still copper.

Current carrying capacity at DC/low frequencies is largely determined by the diameter of the wire, and number of strands. All wire has a little bit of resistance, and when current flows through the wire, the heat generated needs to be dissipated.

As far as the list of 4 factors and insulators, sounds like a class specific bit of data.

"Most Common Insulator" - as cable sheathing, or as an insulator to keep cables further from ground, such as the ceramic standoffs on utility poles?

3. b.shahvir Active Member

Jan 6, 2009
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Hi,

1) I would go with Thatoneguy on this one..........the insulation of a wire cannot affect its resistance as it is just the 'skin' of the wire, just as our skin does not affect the working of our internal organs but acts as protective shield for our body!

2) For determining the factors for wire selection the paper I have attached might come of help to you.

3) The most commonly used insulater for high voltages is porcelain but glass or steatite and special composition materials are also used upto some extent. For further info, you can google High Voltage Insulators.
Hope this helps.

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