Re: MOT Mutual inductance with DC PSU's

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: tesla <tesla@xxxxxxxxxxxxxxx>

Thanks Team
Tried a very interesting expt.
Set up a MOT with a SC sec with its shunts intact. Then replaced the Sec SC
with  TWO MOW caps in parallel. This calculates with my estimate of 6Hy
souce inductance to near 50Hz resoance. The effect is significant, Primary
current went off the ampmeter scale with the variac up to 30%.

So simple cure will be tyo put a MOT cap array in series with the supply to
the Tesla to tune out the inductive source reactance of the MOT's. I need to
think carefully about ratinigs for the caps here as I need to consider
resonant rise I think
Best
Ted L in NZ

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, January 13, 2006 3:34 PM
Subject: RE: MOT Mutual inductance with DC PSU's


> Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>
>
>
> Ted:
>
> I have not found the same thing.  My PSU is (4) MOT's parallel primaries
> series secondaries.  The secondary is grounded between the 2nd and 3rd
> MOT so I have two AC legs 180 deg out of phase at ~4000 VAC feeding a FW
> Rectifier with ~1uF capacitor strings between each DC leg and ground.
> Thus DC output is ~ +6000 VDC one leg and -6000 VDC the other leg. My
> charging reactor is 36 H and my tank cap is ~ 40 nF.
>
> The MOT primary is current limited by an adjustable inductor(currently
> set at 15 mH).  All MOT's still have their shunts.  With the CR(15 mH) I
> pull 17 amps when operating the coil feeding the CR 120VAC(MOT's see ~90
> to 100 VAC).
>
> Without the CR and the MOT's dead short I pull in excess of 75 amps.
> Achieved as high a 30 amp draw by reducing CR inductance.  Haven't
> pushed farther due to concern about blowing capacitor.  See
> www.teslaboys.com for pictures.
>
> Mark R Dunn, P.E.
> Engineering Manager
> Wm. W. Meyer & Sons, Inc.
> 847-673-0312 x244
>
>
>
> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Thursday, January 12, 2006 1:23 PM
> To: tesla@xxxxxxxxxx
> Subject: MOT Mutual inductance with DC PSU's
>
>
> Original poster: tesla <tesla@xxxxxxxxxxxxxxx>
>
> Hi Team
>
> Looking for confirming comments on a problem I've been experiencing with
> a larger DC resonant charging MOT system I'm trying to get going. (90nF
> CP and 30Hy Charging inductance from 6 gapped MOT's (2 in parallel of 3
> in series
> config)
>
> I've configured an earlier 4 (or 6 if extra MOT's are added) MOT stack
> AC system to run as DC with a FW bridge into DC Filter of 1.25 uF using
> 20 MWO caps (across the plus to minus whole 12kv developed at the bridge
> O/P)
>
> I've found the system will not draw much current into the Coil. I've
> concluded that the Magnetic shunts in the MOT's is adding so much O/P L
> to the system that large O/P inductive reactance of the MOT PSU iteself
> adds too much current limiting impedance in a system that requires brief
> pulses to charge the filter caps.
>
> I've noticed in the past that MOT stacks pull much more mains current
> into a very capacitive load and I've always theorised that his was due
> to cancellation of the very inductive O/P Z of the MOT's due to the
> magnetic shunts.
>
> I've removed the magnetic shunts from a MOT and the reduction of
> effective O/P Z is dramatic and I believe that charging Caps via a
> rectifier system is best done with magnetic shunts removed in the MOT's.
> Has anybody experience with this situation ?. The primary current on a
> MOT with a SC secondary with the shunts removed is at least 4 times the
> current with the magnetic shunts in place.
>
> Ta
> Ted L in NZ
>
>
>