Re: [TCML] MOT Measurements

[tesla <tesla@xxxxxxxxxxxxxxx>]

Hi Team

Couple of observations.

I agree in a standard AC design MOT resonance due impact of magnetic shunts 
generating leakage inductance is not an issue relating to resonating with 
the Tesla primary cap unless it is really  really big. However in a DC 
system where MOT's are rectified and MOT's  "see" filter capacitances or 
where secondary side capacitive ballasting is being incorporated all bets 
are off and the impact of the significant inductance needs to be considered 
(about 6Hy per MOT at operating currents and with primary side shorted which 
is equivalent cct when feed by mains). Worth noting in many stacked designs 
the MOT leakage inductances are all in series resulting in an even larger 
inductance thru which the equivalent voltage generator is required to "see" 
the load..


I've found it very difficult to get power out of a MOT (real grunt) unless 
they see a conjugate impedance  (at least a moderatly capacitive load) and 
specifically designs requiring short pulses to charge the filter caps at the 
peak of the cycle have been unsuccessful for me. I interpret the situation 
as being one where getting short current pulses "thru" the leakage 
inductance simply results in the large reactance of that inductance limiting 
the charging current not to mention the high required currents thru the 
diodes and in and out of the filter caps)

The exception being the design (scopeboy et al) where the MOT is AC coupled 
to +ve and -ve peak clamps to generate 2 x pp which works well because those 
designs do provide a correct value capacitive component in the load seen by 
the MOT.

For those who may have interests I have looked quite closely at the impact 
on Secondary inductance in MOT's of DC in the winding for DC inductive 
charging use. (They saturate really quickly and must be gapped s if this is 
to be avoided and even then getting large L and high current capability is a 
real balance)

Best
Ted in NZ

----- Original Message ----- 
From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, December 31, 2008 2:08 PM
Subject: [TCML] MOT Measurements



_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla