Re: MOT current

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: tesla <tesla@xxxxxxxxxxxxxxx>

Hi Team, Ted L in NZ here

The question in my view is actually deceptively tricky.

The answer depends on the reactance of the MOT load and of course the size
of the MOT. Recently appreciated the effect of the effective source
impedance of a MOT. Due to  the magnetic shunts in the MOT the O/P Z is
effectively a voltage generator of about 2kV in series with an inductor of
about 6 Hy and a series resistance (I think of about 200ohms). In an
experiment some time ago I fed a MOT into a single capacitor (0.33uF) with a
static gap across it and measured the peak charging current back into the
cap when the SG had fired at 3 amps. The peak current will depend very much
on the value of the capacitor and the value of the O/P inductance. If the
value of C is such as to tune out ALL the inductive reactance of the source
then the pk current will be maximised. I've test jigged this up and
certainly the mains current with a short circuit load in series with a near
resonant capacitive load goes ballistic.

Because tesla coilers often feed capacitve loads and are interested in how
much peak current can be fed into the capacitor I believe this type of
approach to considering the current available from a MOT is more relevant
than what can be delivered into rms into a resistive load of about 0.5amps.
The maximum power O/P will be obtained from a conjugate load at 50Hz where
the resistive component is the same as the MOT source.

Shortly (after I repair an exploded ASRSG) I intend to try some experiments
with a DC resonant charging 4 MOT stack using a series capacitor (another
MOT cap array) to 'tune out" the effect of the O/P inductance from the MOT
source. I have found that a bridge rectifier load into a capacitor filter is
not a good "match" load compared with a conventional AC tesla. My maximum
current draw from the MOT's was much reduced to that when running the same
tesla as an AC excited machine.

Best
Ted L in NZ