Re: low-cost 1800-amp heating source

On Aug 2, 4:51 am, Tony Williams <to...@xxxxxxxxxxxxxxxxxxx> wrote:
In article <1186051537.860371.213...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Winfield <winfieldh...@xxxxxxxxx> wrote:



Tony Williams wrote:

I was interested in Ken's idea, so sketched a
possible circuit, as below.

+ Pri - Load current
230V high +------////////---------->-----+
T1 ======== |
DC-------////////-----+ |(
+ Sec - | |( L(leak)
| |(
.----------------' | Win's Load.
| \
| - Sec + /Rload
+---////////---------DC \
T2 ======== |
230V low +-------////////----------------+
- Pri +
For quick estimates, could we guess that the DC current
would be 3 to 5 times higher than the peak AC current at
the VA rating of transformer?

I don't think it is even as high as that Win.

If you were to leave the Pri open circuit, connect a
voltage source to the Sec, and turn it up until the
current waveform had nice wide flat tops then the
measured Ipeak could be a reasonable estimate of the
polarising DC amps needed to saturate the core.

3 to 5 times the secondary magnetising current peak
is probably much lower than 3 to 5 times the peak
secondary load current.

The control power would then be the DC amps times
the winding resistances.... but see below on what
could buggerate that low control power.

Given that the DC winding resistance of the transformers is quite
low, the DC- control requirement doesn't look too bad. A fair
amount of DC control current, sure, but not too much voltage...

There could be a little ambush in the two-transformer
saturable reactor. Those two series'd secondaries
may not cancel completely, so there could be a
residual AC voltage at their terminals. I suspect
that the DC current source must have a high enough
compliance/supply voltage such that no AC current
flows in the secondaries.

When they are not saturated, and if they came from a good maker, the
match should be more than good enough to keep this current quite
small. When you start to saturate, you want a capacitor between the
windings to pass the AC that develops because one core saturates when
the other doesn't.

.

Relevant Pages

  • Re: magnetics design -- 60mJ energy impedance matching
    ... the Laplace transform and do it that way. ... doesn't saturate on the highest peak (which would be every peak for a ... then it certainly won't saturate ever ... energy into the primary's magnetic energy, ...
    (sci.electronics.design)
  • Re: What part of "unsupported"....
    ... or wire the "secondaries" of a 120:12.6 and ... and saturate the core of the second one when you give it twice the ... Does core saturation cause that line-frequency buzzing sound? ... That's what I was getting at with the "boost" thing. ...
    (alt.sysadmin.recovery)
  • Re: What part of "unsupported"....
    ... or wire the "secondaries" of a 120:12.6 and ... Does core saturation cause that line-frequency buzzing sound? ... when I was giving your mom twice the MMF she ... caused the core to saturate, ...
    (alt.sysadmin.recovery)