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Brent,
The problem with an A/C system in a sub is actually two
fold. Let me explain:
A/C is used for electrical lines because of the use of
ground (earth). Most A/C components have an external grounding point incase
something goes wrong inside and causes the whole component to become "live".
With a system in a submersible.....you would not only have to provide the two
wires to run the equipment, you would also have to provide the extra ground
fault system to ensure no power is being leaked into the water or the hull. The
electrical design could get pretty complex.
This is not the same as driving a three phased brushless
DC motor....this is much more complex.
Also you have to consider the ramifications to the marine
life if something does go wrong.....you could kill quite a few fish/animals if
your power were to get into the water.
I don't think you could ever totally isolate the interior
(from electrical inclusion from flooding) to prevent power absorption, it
would be nearly impossible. It would be much easier to place a ground fault
system in place to kill the power if it detected the situation.
The problem with A/C....you don't know which way the
current will go. It will take the path of least resistance.....which may not be
the direction you plan for it to go. An A/C power system requires very careful
planning......if you want to use it in a psub.
Also.....as in a previous message....you do not want your
hull to have any electrical potential for it causes
electrolytic problems.
James Long
Owner/Designer
Lil Brother LLC (Instrument Division)
----- Original Message -----
Sent: Monday, August 06, 2007 8:02
PM
Subject: RE: [PSUBS-MAILIST] Battery
Safety Issues
James,
You bring
up a point I was thinking about with regards to grounding the batteries
to the sub. Most paints don't have much if any electrical insulating
properties, so the electrical charge, if it's AC power, would just
migrate through the hull and then out to the surrounding water, and then into
the ground, right? If it's DC power then it's just going to keep mostly to
it's self between the negative and positive points or leads? So what I'm
getting at is that if a sub is built with syntactic foam and/or a heavy
coating of Rhino liner type coating, (of which one or both are likely
to be good electrical insulators) on the interior of
the sub, wouldn't the AC power then have a harder time getting out of the
sub, unless the power systems were grounded to the sub, so the power can get
out easier? I was just thinking that if the power has to leave through
the area where the leak is, and/or through the open hatch, or which your
trying to leave through, you would get a real nasty or deadly shock.
Especially since allot of leaks are jumped on by the operator(s) of the sub,
to fix them.
Regards,
Brent
Hartwig
> From:
lil_brother_llc@bellsouth.net
> To:
personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Battery
Safety Issues
> Date: Mon, 6 Aug 2007 14:07:56 -0500
>
>
Joe,
>
> I think that is a somewhat different type of issue.
Remember that AC doesn't
> require much to shock you. Just providing a
path to ground (earth) will get
> you shocked. On the other hand DC
will only shock you when you provide a
> path to it's opposing
pole.
>
> I can see why you wouldn't want your shore power
energized when cleaning the
> bottom on your boat. A/C is sometimes
"leaky"(motor cases, pump cases, etc.)
> and the leak would be finding
it's shortest path to ground(earth). If you
> got it that path.......it
would be a bad thing(depending on the current
> present). I refrain
from working with A/C as much as possible.....but there
> are cases A/C
is the best method.
>
> Being in a psub filled with water (with
submerged batteries) wouldn't be a
> joy ride, but I don't think it
would be much more than a tingling sensation.
> I don't think you would
be worried much about the tingling sensation anyway.
> You would have
more important things on your mind. But I also would try to
> have my
power leads pretty close to each other.....not separated on each
> side
of the hull. But the design requirements for most electrical systems
>
will have the lead close anyway.......wouldn't be much use if they were not
> connected to the same system. Also...I wouldn't connect my hull to
the
> negative side (as most craft are...like cars).......could present
a problem.
>
>
> James Long
> Owner/Designer
>
Lil Brother LLC (Instrument Division)
> ----- Original Message -----
> From: "Joseph Perkel" <joeperkel@hotmail.com>
> To:
<personal_submersibles@psubs.org>
> Sent: Monday, August 06, 2007
1:36 PM
> Subject: Re: [PSUBS-MAILIST] Battery Safety Issues
>
>
>
> James,
>
> Thank you for the info. I
remember reading an article once with respect to a
> "zone" while
cleaning your boat bottom dockside. I cannot remember the
> details, or
why it was an issue, something regarding stray shore power
>
currents.
>
> In any case, I will look over the electrical
details from a safety
> perspective in great detail.
>
>
Joe
>
> >From: "Lil Brother LLC"
<lil_brother_llc@bellsouth.net>
> >Reply-To:
personal_submersibles@psubs.org
> >To:
<personal_submersibles@psubs.org>
> >Subject: Re:
[PSUBS-MAILIST] Battery Safety Issues
> >Date: Mon, 6 Aug 2007
12:27:37 -0500
> >
> >Joe/Brent,
> >
>
>Yes...you will get some shocking effect, but it will not be severe.
The
> >kill
> >zone with the battery submerged (or breaker
box) will be in-between the
> >positive and negative poles of the
battery/connection.
> >
> >Remember there are underwater
welders that deal with this all the time. It
> >is an uncomfortable
thing to do....but is not life threatening, until you
> >enter the
kill zone.
> >
> >James Long
>
>Owner/Designer
> >Lil Brother LLC (Instrument Division)
>
>----- Original Message -----
> >From: "Joseph Perkel"
<joeperkel@hotmail.com>
> >To:
<personal_submersibles@psubs.org>
> >Sent: Monday, August 06,
2007 7:03 AM
> >Subject: RE: [PSUBS-MAILIST] Battery Safety
Issues
> >
> >
> >Brent,
> >
>
>This is one of those issues in the "back of my mind" as well. I figured
to
> >delve in further at the proper time but, perhaps someone can
elaborate.
> >
> >Joe
> >
> >
> >
>From: Brent Hartwig <brenthartwig@hotmail.com>
> >
>Reply-To: personal_submersibles@psubs.org
> > >To: PSUBSorg
<personal_submersibles@psubs.org>
> > >Subject:
[PSUBS-MAILIST] Battery Safety Issues
> > >Date: Sun, 5 Aug 2007
21:22:09 -0700
> > >
> > >
> > >
>
> >If you have one or more batteries in the pressure hull with you, and
not
> >in
> > >a sealed off area, how do you keep from
being electrocuted, if the inner
> > >hull floods? Will not the
batteries short out in fresh water, and even
> >more
> >
>so in saltwater? I would love to be enlightened. ; )' Perhaps
someone
> > >else wants and/or needs to know as well.
> >
>
> > >Even if the batteries are in pods, or another hull
section, will not the
> > >breaker box cause and other wire cause
your trouble?
> > >
> > >
> >
>Regards,
> > >Brent Hartwig
> > >
> >
> " I kind of like doing the impossible. "
> > >
> >
> ~ Walt Disney
> >
> >
> >
> >
>
>
>
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