Definitely mount it on the boat. Once you make a place for it to mount
wiring it up is simple but I wish I could find a Charles transformer for
less than $500. I need two and the best price I have found is $670 each.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"David&Joan" wrote in message
news:VQllg.104732$iU2.45028@fed1read01...
Whatever you do, don't install the isolation transformer at the dock box,
install it in your boat. That way you can easily take it with you. And BTW
a 30 amp Charles River isolation transformer is less than $500 bucks and
will take less than an hour to install it on your boat.

David

"Glenn Ashmore" wrote in news:tbnlg.112499$Ce1.112216
@dukeread01:

Definitely mount it on the boat. Once you make a place for it to mount
wiring it up is simple but I wish I could find a Charles transformer
for
less than $500. I need two and the best price I have found is $670
each.



Hmm....50A service at 120VAC = 6 KVA.

http://www.charlesindustries.com/main/ma_iso_bost.html
16" x 15" x 12" and weighs 155 lbs....about as much as one passenger.

Can't put it in the bilge where it'll rot in the wet, but try to keep it
as low as possible and near centerline so you don't lean over too far.

Here....justification!:

http://www.charlesindustries.com/main/ma_iso_bost.html

"The Isolation Transformer
The ABYC defines an Isolation Transformer as a
transformer installed in the shore power supply circuit on a
boat to electrically isolate all AC system conductors, including
the AC green grounding conductor on the boat from the
AC system conductors of the shore power supply.
If we are bringing AC shore power aboard to an
electrical panel on a boat, a marine grade Isolation
Transformer should always be used in the shore power
circuit where it comes aboard, and before it reaches the
AC distribution panel or any other device aboard.
The AC shore power current passes through the
transformer's primary windings only, and induces a
current in the secondary windings, which supply the
boat. Primary and secondary windings are insulated
from each other, and a ground fault on the shore side
will not involve our boat.
At its simplest form, a transformer consists of two
coils of wire in close proximity but electrically isolated
from each other, usually wrapped around a common
metal core to contain the magnetic fields produced. If an
alternating current is applied to one of the coils, it will
induce a similar current in the other coil.
Most transformers are designed to step voltage up
or down by having differing numbers of turns in the
two coils. An isolation transformer has the same number
of turns in each coil, serving only to isolate the boat
from the shoreside power, but to give the same voltage.
An Isolation Transformer is used because the shoreside
AC power is referenced to ground. If you are connected
to the earth and you touch the "hot" lead of a normal
shoreside AC service, you will get shocked.
The isolation transformer removes the ground
reference from the ship's service. Neither of the two
sides of an AC circuit on the boat is at ground potential.
Therefore you must contact both sides of the onboard
supply to shock yourself."

There is another issue that hasn't been addressed by the group. That issue
is in-rush current when connecting an isolation transformer. The problem can
be severe if the transformer is correctly sized. I use a transformer that I
had custom made for me in Ankara, Turkey. It is 10 KW and it can use shore
power from 100V to 280V on either 50 or 60 Hz so it is usable anywhere in
the world. The problem is how to keep the in-rush current from popping the
service breaker and one answer is a light bulb in series with the primary.
Once power has been applied, simply throw a shorting switch bypassing the
light bulb before using a load.
Steve

"Larry" wrote in message
...
"Glenn Ashmore" wrote in news:tbnlg.112499$Ce1.112216
@dukeread01:

Definitely mount it on the boat. Once you make a place for it to mount
wiring it up is simple but I wish I could find a Charles transformer
for
less than $500. I need two and the best price I have found is $670
each.



Hmm....50A service at 120VAC = 6 KVA.

http://www.charlesindustries.com/main/ma_iso_bost.html
16" x 15" x 12" and weighs 155 lbs....about as much as one passenger.

Can't put it in the bilge where it'll rot in the wet, but try to keep it
as low as possible and near centerline so you don't lean over too far.

Here....justification!:

http://www.charlesindustries.com/main/ma_iso_bost.html

"The Isolation Transformer
The ABYC defines an Isolation Transformer as a
transformer installed in the shore power supply circuit on a
boat to electrically isolate all AC system conductors, including
the AC green grounding conductor on the boat from the
AC system conductors of the shore power supply.
If we are bringing AC shore power aboard to an
electrical panel on a boat, a marine grade Isolation
Transformer should always be used in the shore power
circuit where it comes aboard, and before it reaches the
AC distribution panel or any other device aboard.
The AC shore power current passes through the
transformer's primary windings only, and induces a
current in the secondary windings, which supply the
boat. Primary and secondary windings are insulated
from each other, and a ground fault on the shore side
will not involve our boat.
At its simplest form, a transformer consists of two
coils of wire in close proximity but electrically isolated
from each other, usually wrapped around a common
metal core to contain the magnetic fields produced. If an
alternating current is applied to one of the coils, it will
induce a similar current in the other coil.
Most transformers are designed to step voltage up
or down by having differing numbers of turns in the
two coils. An isolation transformer has the same number
of turns in each coil, serving only to isolate the boat
from the shoreside power, but to give the same voltage.
An Isolation Transformer is used because the shoreside
AC power is referenced to ground. If you are connected
to the earth and you touch the "hot" lead of a normal
shoreside AC service, you will get shocked.
The isolation transformer removes the ground
reference from the ship's service. Neither of the two
sides of an AC circuit on the boat is at ground potential.
Therefore you must contact both sides of the onboard
supply to shock yourself."

"Steve Lusardi" wrote in
:

It is 10 KW and it can use shore
power from 100V to 280V on either 50 or 60 Hz so it is usable anywhere
in the world.

The modern way of creating a wide ranging, DC to radio frequency
isolation "transformer" isn't a transformer at all......

Whatever input AC voltage and frequency is available over a very wide
range is simply "consumed" by a full wave bridge rectifier and low
frequency DC filter, the same as the power supply in your desktop
computer. The resultant unregulated DC, now from 80 to 400VDC is fed to
a high-powered switching inverter, like your battery-powered inverter,
that feeds off whatever DC is available from the rectifier-filter. Its
output frequency is crystal-controlled, its output sinewave is sampled,
measured and the results are fed back to the inverter's control IC, which
determines the pulse width of the inverter's high powered, high voltage
transistor switching array. Over the range of loads from no load to the
capacity of the unit, output is a virtual sinewave at exactly 60 Hz,
voltage regulated to be rock steady. Because such electronics uses a
high frequency switching system with very lightweight toroid
transformers, unlike the old magnetic transformers, you don't need a fork
lift to haul them down the dock, even though they will create 10KW or
more of stable AC power, completely isolated from the power company and
ground.

This is exactly how the new inverter gensets, like my Honda EU3000i 3KW
work. The "generator" is a very high frequency, permanent magnet, 6
phase alternator built into the flywheel of a 6.5 hp, 1-cyl, computer
controlled by the inverter, engine. It looks just like the stator
windings on an outboard motor it was copied from. Being very high
frequency, in the kilocycle range, the size of the magnetic parts becomes
very small and lightweight. The inverter behind the power outlets merely
rectifies and filters it into DC to run the modified sine inverter from,
instead of rectifing the AC line in the paragraph above.

Switchers are very neat, very efficient pieces of electronic art....(c;