Re: ESL in MMC`s

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Original poster: acmq@xxxxxxxxxxxxxxxx

> Original poster: Finn Hammer <f-h@xxxx>
>
> All,
>
> I am building a MMC for an OLTC. This MMC is
> designed to last, so it is getting quite bulky.
>
> Any extra inductance outside of the primary coil
> loop is basically unwanted, but  in a High C, Low
> L, Low V coil it can get *very* unwanted, because
> of it`s influence on the resonant frequency of
> the primary circuit. It is entering a LC circuit
> where the inductance is only 350µF.
>
> I am therefore going to measure the Resonant
> Frequency of this cap, and calculate the
> Inductance according to 4*pi^2*F^2*L*C=1
>
> I assume that the resonant frequency is due to
> the known Capacitance and the sum of inductances.
> These inductances being: Inductance internally in
> the cap, and inductance of the leads from the signal generator.
>
>
> What I am asking is this:
>
> How do I exclude the inductance of the leads from
> the signal generator from the measurement?

Connect the two leads of the signal generator to the capacitor (maybe
using a series resistor) and connect the oscilloscope leads to the same
points. Look for a notch, that depends only on the series inductance of
the capacitor and wiring. With good capacitors in straight line, you shall
obtain something around 1 uH per meter of length of the string.

Antonio Carlos M. de Queiroz