Saturable Reactor Ballast - further testing 1 and SAFETY note

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Carl Litton" <Carl_Litton@xxxxxxxxxx>

Thank you, Ted.

This thread seems to have generated some interest.  So, we though some
here might appreciate an update on the 8 MOT reactor we configured this
past weekend.

http://hvgroup.dawntreader.net/8motreactor2.jpg

http://hvgroup.dawntreader.net/8motreactor1.jpg


This concept appears to be amazingly versatile with a large number of
possible configurations to address the particular V and I parameters of
its intended application.  We have verified the hypothesis posted Friday
that the control windings may be placed in series rather than parallel
to give a higher and wider control voltage range without ill affect.  In
fact, with the 8 pack above, we placed the control windings of all 4
pairs of MOT's in one continuous series, resulting in a control range of
about 0-100 VDC.

Placing the additional 2 pairs in parallel with the first 2 pairs did,
as expected, drop the high end reactance to 15 Ohms.  The low end
remained 2 Ohms.

READ THIS ****** We also tested the idea suggested here on this list
that the primaries should be placed in 'straight' parallel - that is the
left input tab of one MOT connected to the left tab of its pair partner
and the right to the right of the other.  PLEASE NOTE that this results
in nearly 4000 Volts in the control winding.  It appears that if
identical transformers are used, the primaries must be wired in
'cross/inverse/anti' (pick a term) parallel - that is the LEFT input tab
of one MOT is connected to the RIGHT input tab of the other MOT in the
pair and visa versa in order to have low or no voltage in the control.
Of course, this is predicated on the use of the HV tabs to connect the
secondaries in series, which as you can see is what we are using.
*******

There also appears to be no reason that the primaries of each pair may
not be connected in series (making sure that they are wired such that no
voltage is induced in the secondaries) and then the pairs connected to
each other in parallel.  This configuration may be more suitable for
heavy current work in the 200-300 VAC range.

The suggestion of putting parallel MOT's in each half of the phase in a
240 VAC circuit may possibly be less satisfactory.  The two legs of the
split phase are only 120 VAC *with respect to ground.*  They are 240 VAC
with respect to each other.  The MOT's are floating in this type of SR
and will be subjected to 240 VAC if placed in the circuit in this
manner.  Another consideration is that they will then be 2 inductors in
series and as such, their inductances will be additive in the circuit.

More results soon . . .


Carl Litton




-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Friday, February 24, 2006 10:05 PM
To: tesla@xxxxxxxxxx
Subject: Re: Saturable Reactor Ballast for TC from MOT's

Original poster: tesla <tesla@xxxxxxxxxxxxxxx>

Hi Carl et-al

I agree with Finn this appears to be an invention of importance to
coilers

Another configuration that might work is to configure as an inductive
voltage divider. ie a pair, one with L set high while the mate is low
(like
a potentiometer) This would create a true variable voltage divider
operating
in the range 0.93 down to 0.06.

Not a variac but could be a useful device

Rgds
Ted L in NZ