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Inductor selection

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Hello Board,

I am designing an EMI/EMC compliant circuit to
EN 50121 standard. The Inductor is 100uH(1Amp) . I need advise regarding AXIAl Inductor and RADIAL Inductor .
coil-gif.27208

Does it makes any difference If I use any a RADIAL inductor? . I have seen circuits using AXIAL for EMI/RFI suppression, but afterall Inductor is an Inductor or it makes a difference?

Regards
 

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If both inductors have the same number of turns, the same core size and the ferrite material is the same grade, they will both work the same. If the wire gauge is the same they will get equally hot.
 
Hello Board,

I am designing an EMI/EMC compliant circuit to
EN 50121 standard. The Inductor is 100uH(1Amp) . I need advise regarding AXIAl Inductor and RADIAL Inductor .

Does it makes any difference If I use any a RADIAL inductor? . I have seen circuits using AXIAL for EMI/RFI suppression, but afterall Inductor is an Inductor or it makes a difference?

Regards

It depends on where you are using the inductor. If it is part of a switching regulator circuit, then I would consider the series resonant frequency as this is partly a function of the method of construction and it may have a significant effect on the intensity of ringing in the regulator. If it is being used as part of some sort of filter, then I might consider what the Q is because we usually want very low Q in an EMI filter, especially one on a data signal conductor.

In any case, another key difference between the two examples you show is that the magnetic flux lines are oriented differently in the two and if there is a chance of magnetic coupling to any other loops of metal (like other inductors for example) I would choose the one that is not of the same alignment as those others, in order to minimize coupling.
 
It depends on where you are using the inductor. If it is part of a switching regulator circuit, then I would consider the series resonant frequency as this is partly a function of the method of construction and it may have a significant effect on the intensity of ringing in the regulator. If it is being used as part of some sort of filter, then I might consider what the Q is because we usually want very low Q in an EMI filter, especially one on a data signal conductor.

In any case, another key difference between the two examples you show is that the magnetic flux lines are oriented differently in the two and if there is a chance of magnetic coupling to any other loops of metal (like other inductors for example) I would choose the one that is not of the same alignment as those others, in order to minimize coupling.

Hi Ron ,Its for power supply filtering ,Vishay's Axial 100uH has been suggested as its taking 25mm length and 12mm Width therefore its consuming a good amount of PCB space. I dont feel there would be any coupling with other inductors which are about 2cm away from this one.

If you see the top one AXIAL Inductor it is a single layer wound and the other one RADIAL is multi layer wound , does this has anything to do with RFI filtering quality .The RADIAL one will have air gaps between the layers, This is a concern.

Thanks
 
Hi Ron ,Its for power supply filtering ,Vishay's Axial 100uH has been suggested as its taking 25mm length and 12mm Width therefore its consuming a good amount of PCB space. I dont feel there would be any coupling with other inductors which are about 2cm away from this one.

If you see the top one AXIAL Inductor it is a single layer wound and the other one RADIAL is multi layer wound , does this has anything to do with RFI filtering quality .The RADIAL one will have air gaps between the layers, This is a concern.

Thanks


I would want to see its behavior of inductance vs frequency. If it is not a single layer coil, I'm guessing that the inter-winding capacitance is more and it might transition towards resonance at a lower frequency than the other one. The main effect will be that the filtering will be effective up to a lower frequency than the axial one, and I don't know what frequencies you are targeting with this filter.
 
I would want to see its behavior of inductance vs frequency. If it is not a single layer coil, I'm guessing that the inter-winding capacitance is more and it might transition towards resonance at a lower frequency than the other one. The main effect will be that the filtering will be effective up to a lower frequency than the axial one, and I don't know what frequencies you are targeting with this filter.

Please have a look at here https://www.electro-tech-online.com/custompdfs/2009/03/EN205012120Railway20Standard.pdf this should provide some hint to the standard .
Its basically for Surge tolerrance like 1800V with lasts for about 50uS and has a source impedance of 100E. And sustaining Transient bursts EN50121-3-2 etc type standards. The succeptablity to EMI is from KHz to GHz .
 
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