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 22:31:09 -0500
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 -----
From: Brent Hartwig
To: personal_submersibles@psubs.org
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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