[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: ESL in MMC`s

Original poster: "Steve Ward" <steve.ward@xxxxxxxxx>


Charge up the MMC to 50-100V or something, place a CT on one end of
the cap, and short out the cap through this lead with the CT.
Depending on your caps construction, this wire might be very short, so
its effects will be negligable.  Or perhaps you could approximate its
inductance.  Anyway, when you short the cap, it would give a step
response with a ringdown.  You can watch the current ringdown on a
scope and calculate the period from that.

Or, i guess skip the CT and just watch the cap's voltage, either way
will show you the period so you can calculate the frequency.


On 8/13/06, Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: Finn Hammer <f-h@xxxx>


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