Re: [TCML] Inductor design program?

[David Dean <deano@xxxxxxxxxxxxxxxx>]

On Friday 23 April 2010 12:06:57 pm jhowson4@xxxxxxxxxxx wrote:
> I see, 
> so I can use the slope to obtain XL 
> which is equal to 2*pi*60*L 
> which can be used in the ohms law equation like this? 
> 
> V/( I*2*pi*f)=L 
> so (140 V) / (30 A * 120*pi) =12.4mH ? 
> 
> which seems wrong to me because I have always seen mention of 100mH
>  inductors being used? 
> 
Lets see:

2*pi*f=w ;  (w stands for omega (lowercase), I don't have Greek letters on my 
keyboard and who knows how mail clients may treat the ASCII code for the proper 
symbol. omega is in units of *radians per second*)

Let f = 60Hz;
So w=377;  (2*3.1415*60)

X(L)= 140V/30A= 4.67Ohm;

L= X(L)/w = 4.67/377 = 12.4mH

Now lets take the other case.

100mH = 0.1H;

X(L)=wL = 377*0.1 = 37.7Ohms;

140V/37.7Ohms= 3.71A which is considerably less than 30A.

So it looks like it all works out just fine. I would rewrite your formula as:
( V/ I)*(2*pi*f)=L because sometimes the order of the parentheses can make a big 
difference.

later
deano
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