Re: OLTC maggy

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "boris petkovic by way of Terry Fritz <teslalist-at-qwest-dot-net>" <petkovic7-at-yahoo-dot-com>


 > The coupling in a typical OLTC (well, both of the
 > OLTCs that exist) is so
 > high that it might as well be a magnifier. Terry's
 > and mine both quench
 > after about 3 cycles, suggesting a coupling around
 > 0.25. Having said that,
 > if the energy transfer were speeded up even more,
 > like to 0.5 or 1 cycle,
 > it could reduce "gap" losses.
---
Energy transfer in 0.5 cycles isn't possible.
Both in magnifier and ordinary TC you need 1 cycle at
least.
---



  This is a good thing
 > because the IGBTs are
 > probably more lossy than a real spark gap. Are
 > transfer times this fast
 > possible with a maggie?
---

mode (1,2,3) is the  mode with the smallest coupling
between primary-secondary that allows 1 cycle transfer
in 3 coil system.But,the smallest here means k=0.67(!)
Yes, there are constructing ways to get that
high.Particulary interesting, in OLTC design with a
big cap and only 1 primary turn,with driver coil ratio
H/D<1.
Of course ,usual design is a must  with 2 and more
primary turns with H/D>1 but encountering isolation
difficulties with higher bang energies(after all,oil
immersing is always way out).
However,I would strongly recomend you to go for mode
(2,3,4) and transfer in 1.5 cycles with k=0.57.
Not becouse k=0.67 looks scarrry but there is
another,special reason I opt for that.
Since you are reading Antonio's paper think why.
If you don't figure it out, Antonio or I will tell
you.
---
 > On the other hand, one of the problems I had with
 > the OLTC was that the
 > secondary kicks back into the primary after turnoff,
 > and partially
 > recharges the tank cap via the flywheel diodes. This
 > interferes with the
 > charge circuit and makes the bangs smaller than they
 > should be. The higher
 > the coupling, the worse this effect is. So on a
 > magnifier it might be
 > unacceptable. It can be combated by just increasing
 > the supply voltage, but
 > then if the cap were to start off fully discharged
 > for some reason, you'd
 > blow something out.
---
That's a good point.I think this trouble isn't
unsolvable problem.OLTC concept being rather new but
developing and improving very fast.There are already
some experts on it (For instance,I find Terry to be
one ).
Note also that if you miss considerably exact tuning
point in these high ranges we are talking about,
an incomplete energy transfer will happen in higher
percantage than usual.That may cause some problems.


If you decide to construct the system let the list
know.

cheers,
Boris