TDMM 13 Chapter 9 Power Distribution Question
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TDMM 13 Chapter 9 Power Distribution QuestionExpand / Collapse
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Posted Saturday, March 21, 2015 9:33 AM
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TDMM 13 page 9-16 Solid Conductor Diameter

In this section, it is stated that "If starting with the fixed diameter of 4/0, then each smaller size is derived from the previous size by multiplying it by a factor of 1/R = 0.89052571".

Can anyone explain where 1/R = 0.89052571 came from. It follows that R would = 1.122932205966294 and therefore diameter would be 2.245864411932588 and that makes no sense at all.

The example is starting with 4/0 cable which is 0.46 inch diameter. Radius = 0.23 inch.

I find this section really confusing.
Post #9719
Posted Saturday, March 21, 2015 12:12 PM
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"R" does not stand for "Radius" in this case. It is a constant that represents the relationship between the diameters in any two successive gauges in the AWG system.

Quoting from the Wikipedia entry on AWG:

By definition, No. 36 AWG is 0.005 inches in diameter, and No. 0000 is 0.46 inches in diameter. The ratio of these diameters is 1:92, and there are 40 gauge sizes from No. 36 to No. 0000, or 39 steps. Because each successive gauge number increases cross sectional area by a constant multiple, diameters vary geometrically. Any two successive gauges (e.g. A & B) have diameters in the ratio (dia. B ÷ dia. A)(approximately 1.12293).

http://en.wikipedia.org/wiki/American_wire_gauge
Post #9720
Posted Saturday, March 21, 2015 11:29 PM
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Well that certainly helps explain things a little better. There should have been a reference the what "R" is. I wish the TDMM would be a little more consistent with the description or explanation of the formulas they publish.

Thanks for the reply.
Post #9723
Posted Wednesday, October 17, 2018 11:23 PM
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The questions you give are very good and practical, I appreciate your questions.
asianfanfics


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