I have been paralleling plate xfmr secondary's since 1977..with zero
issues.
Back then, it was 80 lb hammond plate xfmrs. Those came with a 0-105-110
-115-120 primary...and the usual CT secondary.
We would series the 120 vac primary's to run on 240 vac. Then parallel
the secondary's.
Zero issues.... and a 50-50 split.
I still have a pair of 80 lb hammond plate xfmrs configured like
this....used on a hb 2 x 4-400 amp.
Both Asamoto and also Henry radio paralleled plate xfmr's (both pri and
sec) on their RF generators and also FM broadcast PA's. Some of the FM
broadcast PA's used 3 phase supplies, either 208 3 phase, or 360 vac 3
phase. On their single phase versions, 2 x identical plate xfmr's were
used....again with pri in parallel..and sec's in parallel.
And no, nobody is gonna wire plate xfmr secondary's in SERIES. Why
would you ? As is, these xfmr's have 4300 and also 5300 taps. Why
the hell would u even think of series 2 x 4300 secondarys....u would end
up with a whopping 8600 vac = 12.16 kvdc. And 14.9 kvdc if the 5300 taps
were used.
The pair of plate xfmrs used on the 16 kva supply are identical. That
combo, using the same xfmrs is already in use in the above mentioned
commercial applications......was done all the time.
I went through all this with Dahl himself. One of my options was to
parallel both pri and sec of his 127 lb xfmr's. ZERO issues with that
proposed config...using 2 x identical 127 lb xfmrs.
( I ended up opting for a single 253 lb Dahl).
Xfmrs are made to an exact winding spec. XX turns on the pri...and YY
turns on the sec. Why u think there is gonna be a V difference between em
is beyond me.
The only trick is.... to get the phasing correct ( both pri and sec). IE:
left side pri terminal on xfmr #1 is in parallel with the left side pri
terminal of xfmr #2. And right side terminals bonded. And ditto with
the sec of each xfmr. Get one of those reversed, and you will blow the
primary fuse / breaker asap. This is why for initial testing, a variac
is used, with a real small fast fuse installed.
2-3-4 plate xfmrs have been used, with pri's and also sec's in
parallel...and zero issues. Same deal with pole pigs.
Installing a FWB assy on the output of each sec will also work..then
paralleling the outputs of each FWB assy...... but it's a wasted effort.
And putting a resistor in series with the paralleled FWB outputs....to
the filter caps is a huge no-no. You will destroy the regulation in a
heartbeat due to the high pulsed currents every 8.3 msecs.
A client wanted a 25 kw pep output 80-10m amp, using a 3x15 tube in GG.
Heyboer highly recommended using 2 x identical plate xfmrs...with both
pri's in parallel.....and also sec's in parallel....done all the time with
a 50-50 split. This was 2 x 20 kva xfmrs in parallel.
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