# Re: ESL in MMC`s

```Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Finn,

There is this:

http://www.elecdesign.com/Articles/Index.cfm?ArticleID=1822&pg=1

However I am not sure abut the "Q".

```
If the inductance is say 100nF and the capacitance is 10uF with 0.02 ohms then the Q is:
```
Q = SQRT(L / C) / R = 5

```
So there is a chance the Q would be real low and the waveforms might be hard to pick out.
```
There is this:

http://emcesd.com/tt020100.htm

http://www.mwrf.com/Articles/ArticleID/5450/5450.html

"Maybe" this will help.

Cheers,

Terry

At 05:20 AM 8/13/2006, you wrote:
```
```All,

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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?
```
I will post pictures of the cap as soon as it is completed.

Cheers, Finn Hammer

The capacitor is made from 99pcs.

```
Cornell Dubilier 940C12W1P5K-F caps in a 33/3 configuration for 16.5µF @ 3600VDC/1500VAC Ipeak=21100A Iavg=478.5A
```

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```

```