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posted to rec.boats.electronics
chuck
 
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Default Isolation transformer and connection to ground

Thanks for the info. I was not aware of the product and as you can
imagine, I have no experience with it. My comments are therefore
necessarily abstract.

The two primary advantages of a switch-mode device are lower weight
(less iron) and a built-in capability to regulate output voltage (and
perhaps adjust for different input voltages) automatically.

Potential disadvantages, however, are numerous. The standard isolation
transformer is perhaps the most reliable electrical component we have.
Switch-mode circuits tend to involve many electronic components, some of
which operate under life-shortening stresses. While an isolation
transformer could easily outlast a boat, I doubt the same could be said
of the vastly more complex switch-mode devices.

Without examining the actual circuit, it is impossible to discuss the
degree of isolation achieved or the potential isolation fault modes of
the device.

No mention is made in the specifications about the purity of the sine
wave output. For some appliances, this may not be critical; for others,
it is very important. Possible electronic noise from the switching
circuits could also be troublesome. While modern switch-mode circuits
can be designed to deal acceptably with these issues, it is difficult to
evaluate the product to which you refer since no mention of them is made
on the website.

Other considerations are susceptibility to noise and voltage transients
(e.g., lightning) on the shore power line and radio frequency
interference from onboard radios, battery chargers, fluorescent lamps,
and radar.

It is unclear how the ABYC and various EU standards will view such a device.

Sorry I can't offer anything more specific. Perhaps others have had some
experience with switch-mode isolation devices.

Good luck.

Chuck



Daniele Fua wrote:
chuck wrote:
...snip


A short on either primary or secondary would trip the breaker, of
course, provided it has been sized properly.

...snip

Chuck



I am following your discussion with much interest as I am planning to
install very soon an isolation transformer in my boat.
I add a further question: I have just learnt that a firm is going to
commercialize a Switch-Mode Isolation Transformer (they claim is the
first in the world!) and, if you are interested, just make a Google
search. My question is: is it indeed equivalent to the ol' faithful and
massive isolation transformers?

Thanks for your help
Daniel