Guest orinoco Posted October 15, 2004 Share Posted October 15, 2004 I am familiar with this current density and that higher the freq goes, less current goes in the middle and more on the skin. But CSA 1mm is not 1 square mm. CSA 1mm is simply d² , but 1 square mm is ∏r² ... 27517[/snapback] Off out for a beer now (I do have a life) I'll answer your question when i get back and my mind is suitably refreshed... Regards Bellman 27535[/snapback] man i cant wait for part 2, especially when the beer kicks in. Link to comment Share on other sites More sharing options...
bellman Posted October 16, 2004 Share Posted October 16, 2004 I am familiar with this current density and that higher the freq goes, less current goes in the middle and more on the skin. But CSA 1mm is not 1 square mm. CSA 1mm is simply d² , but 1 square mm is ∏r² ... 27517[/snapback] Off out for a beer now (I do have a life) I'll answer your question when i get back and my mind is suitably refreshed... Regards Bellman 27535[/snapback] man i cant wait for part 2, especially when the beer kicks in. 27572[/snapback] Brian beat me to it... Regards Bellman Service Engineer and all round nice bloke ) The views above are mine and NOT those of my employer. Link to comment Share on other sites More sharing options...
Guest Posted October 16, 2004 Share Posted October 16, 2004 What I found from the web is that CSA is announced in Circular mils (d²) not ∏r² .. Thou I do not have absolute facts, just what I found from the web: http://www.allaboutcircuits.com/vol_1/chpt_12/2.html http://ourworld.compuserve.com/homepages/b...th/condfill.htm try google and circular mils Link to comment Share on other sites More sharing options...
bellman Posted October 16, 2004 Share Posted October 16, 2004 Part 2... Right, Thinking cap on Georg, A circular mil is the area of a circle having a diameter of 1 mil, as shown in your diagram above. The area in circular mils of a round conductor is obtained by squaring the diameter, measured in mils. Thus, a wire having a diameter of 25 mils has an area of 252, or 625 circular mils. To determine the number of square mils in the same conductor, apply the conventional formula for determining the area of a circle (A = pr2). In this formula, A (area) is the unknown and is equal to the cross-sectional area in square mils, p is the constant 3.14, and r is the radius of the circle, or half the diameter (D). Through substitution, A = 3.14, and (12.5) 2; therefore, 3.14 x 156.25 = 490.625 square mils. The cross-sectional area of the wire has 625 circular mils but only 490.625 square mils. Therefore, a circular mil represents a smaller unit of area than the square mil. If a wire has a cross-sectional diameter of 1 mil, by definition, the circular mil area (CMA) is A = D2, or A = 1 2, or A = 1 circular mil. To determine the square mil area of the same wire, apply the formula A = pr2; therefore, A = 3.14 x (.5) 2 (.5 representing half the diameter). When A = 3.14 x .25, A = .7854 square mil. From this, it can be concluded that 1 circular mil is equal to. 7854 square mil. This becomes important when square and round conductors are compared. from this we can use the following to convert between the 2 different standards of measurement. When the square mil area is given, divide the area by 0.7854 to determine the circular mil area, or CMA. When the CMA is given, multiply the area by 0.7854 to determine the square mil area. The man to speak to over this is dale as he teaches this stuff. I hope this clarifies the point for you Regards Bellman Service Engineer and all round nice bloke ) The views above are mine and NOT those of my employer. Link to comment Share on other sites More sharing options...
bellman Posted October 16, 2004 Share Posted October 16, 2004 Just been reading the two links that you posted in your previous message Georg, They both explain how to convert between the 2 standards From the first link:- "Because this is a unit of area measurement, the mathematical power of 2 is still in effect (doubling the width of a circle will always quadruple its area, no matter what units are used, or if the width of that circle is expressed in terms of radius or diameter). To illustrate the difference between measurements in square mils and measurements in circular mils, I will compare a circle with a square, showing the area of each shape in both unit measures:" and from the second link:- "The square mil is the area of a square whose sides are each one mil (0.001 inch). Hence, the area of a square mil is 0.001 squared, or 0.000001 square inch. With reference to the previous definitions of the circulare mil and the square mil, it is obvious that in order to convert a unit of circular area into its equivalent area in square mils the circular mil must be multiplied by Pi/4, or 0.7854, which is the same as multiplying by 1.273. These relations may be written as: Area = diameter squared = circular mils (CM) Square Mils = circular mils times 0.7854 = circular mils divided by 1.273. Circular mils = square mils divided by 0.7854 = square mils times 1.273." Regards Bellman Service Engineer and all round nice bloke ) The views above are mine and NOT those of my employer. Link to comment Share on other sites More sharing options...
bellman Posted October 16, 2004 Share Posted October 16, 2004 banghead Where's Dale when I need him !!! Regards Bellman Service Engineer and all round nice bloke ) The views above are mine and NOT those of my employer. Link to comment Share on other sites More sharing options...
Guest Posted October 16, 2004 Share Posted October 16, 2004 thanks bellman, there is no problem converting between these circular mils and square millimetres but is CSA announced in square millimetres or circular mils. This I found from the web: http://www.lanshack.com/DesigningConduitRuns.asp ___ Link to comment Share on other sites More sharing options...
bellman Posted October 16, 2004 Share Posted October 16, 2004 In the UK csa is usually expressed in square mm but either can be used... by the way, you were right in your calculations earlier Circular mil... So if CSA is 1mm it is 0,7854 square mm --> CSA0,2 mm --> 0,157 square mm.. Right?because of the formula A = pr2; therefore, A = 3.14 x (.5) 2 (.5 representing half the diameter). When A = 3.14 x .25, A = .7854 square mil. From this, it can be concluded that 1 circular mil is equal to. 7854 square mil. regards Bellman Service Engineer and all round nice bloke ) The views above are mine and NOT those of my employer. Link to comment Share on other sites More sharing options...
Guest Posted October 16, 2004 Share Posted October 16, 2004 I am rarely wrong in my calculations So from now on i except CSA to mean square millimetres.. Unless mentioned otherwise. So, Bellman.. Were you real Bellman yesterday and drink boxes of Bell's or just having a beer? I noticed that you posted something after you got home..? Link to comment Share on other sites More sharing options...
bellman Posted October 16, 2004 Share Posted October 16, 2004 Was drinking Guinness until pub shut, then went round to a mates flat and started drinking again there, posted from his net connection whilst i was there. brain was far to addled to reply last night so i thought i'd do part 2 this morning after i got up... Glad it's all clear and understandable now for you. Regards Bellman Service Engineer and all round nice bloke ) The views above are mine and NOT those of my employer. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.