On Sat, 29 Nov 2003 12:02:41 -0800, Peter Bennett
wrote (with possible editing):

On Wed, 26 Nov 2003 14:28:34 GMT, L. M. Rappaport
wrote:


I think there are two kinds. One type uses a swinging core in the
transformer and works by adjusting the output voltage. The other uses
what is known as a "ferroresonant" transformer which works by
saturating the core at resonance with a non-polarized capacitor which
keeps the output steady regardless of input voltage swings. In a
marine environment, I'd opt for the latter as there are no moving
parts.

However, you can have problems when using a ferroresonant tranformer
or charger on a genset or other off-grid power sources, since the
ferroresonant transformer depends on the power frequency being very
close to 60 Hz. If the frequency shifts, the transformer output
voltage will also vary.

I haven't the experience, but you are probably correct. Resonance
would depend upon the "Q" of both the transformer and capacitor.
Another important consideration is that while ferroresonant
transformers might work for charging batteries, since they operate
using square waves (core saturation), they are usually not recommended
for running electronic equipment or anything sensitive to spikes.
Battery charging is ok, however, since the battery acts like a big
sink for spikes.
--

Larry
Email to rapp at lmr dot com