# How to Find Capacitance between Coil, Magnetic Core and Shield.(Need Help)

#### Xeeshan143

##### Newbie level 5
Hello I want to Find the Capacitance between the Coil, Magnetic core and Aluminum Shield in HFSS, Please help me out, how can I found the capacitance between each part. I will be thankful to your kind reply.

Thanks

#### Attachments

• 1AA.jpg
279.4 KB · Views: 24

#### FvM

##### Super Moderator
Staff member
Use plate capacitor formula?

#### BigBoss

$C=\epsilon_{0}\epsilon_{r}\frac{A}{d}$

#### dick_freebird

I imagine the equation may be different for cylindrical structures
as field lines converge / diverge. Maybe not by much if "d" << r
(radius of curvature, of the "plates"). Toroidal may compound this
(two curves). And there, also the outer face becomes sparse (not
"plate". But I expect you could "unroll it in your mind" and get a
parallel-plate-squashed-flat approximation that would be a
roughly right value (finer points aside) to check work.

I gather the object of the exercise is for the student to learn HFSS,
rather than the practical value of measuring real stuff in place of
simulator noodling. If this was a real physical assembly then the
measuring could have been done long since.

But the little I know about HFSS, is that it should work from a
physical mesh (FEA) and figure it all out so you avoid solving
equations by hand where it's impractical due to complexity /
influence of picky details.

So I'm not sure any relevant (i.e. concisely answerable) question