skin effect and proximity effect

[morgan3520]

Hello, how do you calculate the component ac resistance resulting from skin effect and proximity effect (Y_c) from equation 311.60(B).

 

[David Castor]

You can start here: https://www.electricalengineeringtoolbox.com/2014/07/ac-resistance-of-conductor.html

There are also tables of ac/dc resistance ratios that should get you pretty close.

 

[morgan3520]

You can start here: https://www.electricalengineeringtoolbox.com/2014/07/ac-resistance-of-conductor.html

There are also tables of ac/dc resistance ratios that should get you pretty close.

I am looking at the chart (see below) so R/R₀ = Y_c? How do you differentiate between conductor sizes?

 

[David Castor]

There was nothing attached. But just be aware that almost no one ever uses this method for determining ampacity, at least in my experience. Is there some unusual application where you don't think you can use the values in the NEC Tables?

 

[morgan3520]

There was nothing attached. But just be aware that almost no one ever uses this method for determining ampacity, at least in my experience. Is there some unusual application where you don't think you can use the values in the NEC Tables?

My supervisor wants me to develop an Excel spreadsheet using Neher-McGrath equations as a standard spreadsheet for our department (she is aware of software that does this). see attachment, this is what I was referring to last message. I am trying to get a grasp of the equations to do hand calculations.