3 ph to 1ph transformer conversion WAS: How about this for a power supply

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Original poster: "David Sharpe by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

All

Ok I checked my candidate VTTC transformer.  It is a 230V Delta primary
(no taps), 2600V L-L secondary, 7kVA.  Vacuum inpregnated epoxy
windings.
 So I disconnected 'B' phase low voltage connections and tied LV in
series across
existing 3 connecting studs.  I applied 120VAC across A-C HV connections

and measured A and C low voltages across primary windings...
AC (H1,H3)       AC (L1, L3)
120                     10.03       9.94

If calculated from previous posting  2600/sqrt(3) ~ 1500V
Vs/Vp = Turns Ratio = 6.52

Measured            60V across each HV winding / AC (L1,L3 above)
5.98   6.03

By proper phasing of L1 and L3 windings will result in sum of turns
ratio
(12.01:1)
With 240 on each winding will result in AC output H1 to H3 of
240*12.01 or nearly 2900V, as compared to 2600V originally.
Why apparent reduction in turns ratio based on nameplate?  IMO, it may
be caused by increased leakage inductance in core since 'B' phase
winding
is no longer used, and mean magnetic path is longer.

kVA of new assembly would be 57% of original (7*0.57) ~4kVA,
in VTTC 10kVA (2.5X original) is possible for staccato mode and
short duty cycles.  FWIW.

Regards
Dave Sharpe, TCBOR
Chesterfield, VA. USA