Re: AC wire resistance with proximitry effects

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Bart,

I agree.  At the time I started the post, I had forgotten that WoL/R 
was an intermediate result.  My main concern is that the correct L be 
used with your equation (or the correct L and C be used with my 
equation).  The effective L is smaller than Ldc and can't really be 
measured correctly because of the current profile. Same goes for 
effective C.  I'm assuming that your Les and Ces are correctly 
calculated from the FEA portion of your program and can be used to 
calculate Q.  Also, the peak frequency response, in general, will be 
smaller than that associated with Wo (except for an infinite Q coil 
where ESR is zero).

Take care,
Gerry R.

> Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
>
> Hi Gerry,
>
> The equations are identical, but there are considerations. When 
> using Q=sqrt(L/C)/R, assuming R is the same for both forms, the 
> final value will only be identical when Wo=w (1/sqrt(LC)=2pi*F). To 
> ensure this is true, it's best to measure L and calc C or 
> vice-versa. I simply find it easier to implement as Q=wL/ESR. This 
> removes an incorrect input situation if L and C are actual inputs 
> and if C is found from L, than it saves a step.
>
> Take care,
> Bart
>
>
>
> Tesla list wrote:
>
> > Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>
> >
> > On 10 Oct 2005, at 11:47, Tesla list wrote:
> >
> > > Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> > >
> > > Hi Bart,
> > >
> > > I understand now what you are saying.  One thing I might question is
> > > your equation for Q.  I dont think this is the right equation for a
> > > series RLC circuit:
> > >
> > > The RLC Laplace impedance is sL + R + 1/sC
> > >
> > > I(s) = V(s) / sL+R+1/sC
> > >
> > > to put in standard form:
> > >
> > > I(s)/V(s) =  (s/L) / (s^2 + sR/L + 1/LC) = (s/L) / (s^2 + s Wo/Q +
> > > Wo^2)
> > >
> > > Wo =  sqrt (1/LC)
> > >
> > > R/L = Wo/Q
> > >
> > > Q = WoL/R = sqrt (L/C) / R
> > >
> > > Gerry R
> > >
> > >
> > > >Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
> > >
> > > >First, regarding Ldc. Your right, it's not in the equation for
> > > >Fraga, but it is used when predicting Q. Here is what I'm doing, at
> > > >least at this time.
> > > >
> > > >ESR = wL/Q
> > > >Q = wL/ESR
> > > >I am replacing ESR with Fraga's resistance because it is a combined
> > > >R.
> >
> > I'm struggling to see a difference apart from Bart defining "R" as
> > "ESR" which is quite correct.
> >
> > ??
> > Malcolm
> >
> > >
> > >
> > >
> > >
> > >