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RE: ballasting, alternators, Saturable, controllable cores

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Thanks for the reply!

Presently, I am not using the genset as a machinist is setting up the
registration between the diesel flywheel and the flex plate from the
armature. I am limiting my dedicated single phase 70amp 240v Edison circuit.
However, the idea of limiting the field current in the alternator is
intriguing and since Tesla invented the rotating magnet field to begin with,
highly appropriate.

Clearly, I am going to have to crack the books on this. The alternator
schematic clearly shows the exciter field bridge diode assembly's connection
to the regulator transformer along with the suppressors rv1 and rv2 across
the main and exciter fields and the six pulse diode assembly.

The alternator is presently wired for 277/480 volt wye output operation. I
planned to scale it back to 139/240 which is where the variac consideration
also came into play when the "big one" hits here. I mention the suppressors
on the fields as it is nagging to me that the generators smoked in Colorado
Springs due to some reflected harmonics back from Tesla's coil, did they

So much to learn, so little time... I should mention that this is a heavy
duty alternator, very conservatively rated at 18.7 KVAR with very heavy
windings. The armature shaft is 2".

Jim Mora

Harvey, if Terry would be so kind, I could scan the schematic inside the
termination box for your clarification remarks, and to augment my limited
education in this area. My neighbor down the street rewinds motors for the
oil patch here; but, I would rather not have to humbly bring it to him :-^)

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Sunday, February 05, 2006 1:39 PM
To: tesla@xxxxxxxxxx
Subject: Re: ballasting not revisited, Saturable, controllable cores

Original poster: Harvey Norris <harvich@xxxxxxxxx>

--- Tesla list <tesla@xxxxxxxxxx> wrote:

 > Original poster: Steve Conner <steve@xxxxxxxxxxxx>
 > >Still working on my 3 phase monster... 3 2950
 > Superiors in a stack
 > >for voltage control. A 20KW 3 phase generator
 > driven by an Isuzu
 > >diesel (not a factory unit!)
 > Why are you bothering to lug a big variac stack and
 > saturable
 > reactors, when you can easily control voltage by
 > adjusting the field
 > excitation on the generator?
 > Steve Conner
 > http://www.scopeboy.com
Yes I was also going to comment on this matter as
there may be more here then mere control of output
voltage by the generator, if designed as the rotating
electromagnet field of an alternator by amount of
causitive field excitation. In this situation the
stator output can be tested for its current limitation
by shorting the output windings, (which also
determines R(int) by division of respective V and I
readings) and then increasing the field current until
the designated current output is reached. It is here
in making this assumptive field measurement that we
discover that the field itself being a DC pole face
assembly that mimics an AC output by design of
triangular flux leakage in mechanical rotation
interacting with the circular stator rim: this field
itself is a non-linear resistance, easily appearing
higher in resistance in rotation then when not in
motion. In fact it is not until the  stator output
voltage is doubled from its prexistant rotational one
that the amount of field current begins to
significantly reflect the availability of stator
current. In any case the fact that the primary of the
transformer can be ballasted by the amount of field
current in the AC alternator as a current limited
supply; this has further ramifications on the
transformer output end which is operating a primary
arc gap. In this case the effect of shorting the
alternator  stator itself is to cause its output
voltage to drop to its lowest possible operational
point, thus also withdrawing voltage for the operation
of the primary arc gap, making for  the possibility of
a better quenched arc, all of this dependent on the
time lag between currents on the secondary and the
primary, and how the secondary draw influences the
primary one.