Self capacitance of a multi layer coil

[hobbs125]

Hi everyone,

I am trying to figure out how to correctly calculate the self capacitance of a multi layer coil.

I have been trying to find an online calculator or software which can do this but I don't really know where to look.

Just hoping someone here can give me some insight. Any help will be greatly appreciated!

 

[NascentOxygen]

Perhaps you'd better define "self-capacitance". Self-inductance I can grasp, self-capacitance is more nebulous. Can you draw a schematic and show a capacitor marked "self-capacitance"?

 

[sophiecentaur]

At a low frequency, the self inductance should be fairly easy to calculate if the coil is of standard construction. The self capacitance is something that will be much harder to determine because it will be frequency dependent. There is a capacitance 'between the connecting terminals' (in parallel with the nominal L) because of the proximity of the turns at each end and this will resonate (parallel resonance) at a certain frequency with the L and increase the effective impedance of the coil. This frequency can be found experimentally with a sweep oscillator but is very hard to predict. I would search with terms like "RF coil winding techniques" and "Parasitic capacitance of coils"

I found this.

 

[Carl Pugh]

The Book "Electronic Transformers and Circuits" by
Reuben Lee, Leo Wilson & Charles E. Carter has two pages describing how to calculate the distributed capacitance of a transformer coil.

 

[alphysicist]

Hello!

Calculating the self capacitance of a multi layer coil can be a bit complex, but here are some steps you can follow to get an accurate estimate:

1. Determine the dimensions of your coil - this includes the number of turns, the diameter, and the length of the coil. These parameters will affect the self capacitance value.

2. Calculate the inductance of your coil using a formula such as the Wheeler formula or the Biot-Savart law. This will give you a starting point for your calculations.

3. Use the calculated inductance to find the self capacitance using the formula C = 1/(4π²f²L), where f is the frequency and L is the inductance.

4. Take into account the effects of the multiple layers by using the formula for capacitance of a parallel plate capacitor, C = εA/d, where ε is the permittivity of the material between the layers, A is the area of each layer, and d is the distance between the layers.

5. Finally, to get a more accurate value, you can also consider the mutual capacitance between the layers, which is the capacitance between two adjacent layers. This can be calculated using the formula C = εA/d, where A is the area of overlap between the two layers and d is the distance between them.

I hope this helps! Keep in mind that these calculations may not give an exact value, as there are other factors that can affect the self capacitance of a multi layer coil. It may be helpful to consult a professional or use specialized software for a more precise estimation. Good luck with your research!