[PSUBS-MAILIST] DNVGL

Sat Oct 21 21:49:32 EDT 2017

Scott,
earth can mean a common return path for electrical current, as
in a car. That is what I was referring to.
Didn't know you were going through the whole process. What fun!
I have kind of given up on it as I am building a lot of stuff myself, 
like lights, thrusters, solenoid ballast valves & electronic contents gauge.
All these would need to go through their type approval process.
I believe they have a list of DNVGL type approved items that you can 
choose from if you want something off the shelf.
Something I found amusing was that they said you need 4 days emergency
food. I asked them what they meant by this, "2 chickens in a chilli bin"
They specified seven oceans emergency rations!
Cheers Alan

Sent from my iPad

> On 22/10/2017, at 1:56 PM, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
> 
> I believe you mean there is no Negative or Positive connected to the frame. Earth is neither negative or positive. We are going through the full process and have been working with Jonathan Struwe from DNVGL. Our batteries are lead acid and are coincidentally the exact same as DSV Alvin uses. 
> 
> Thank you,
> Scott Waters
> 
>> -------Original Message-------
>> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>> Subject: Re: [PSUBS-MAILIST] DNVGL
>> Sent: Oct 21 '17 19:38
>> 
>> Scott, River.
>> I had a technical advice contract with DNVGL. The reason being so that
>> I
>> could build to their specifications without going through their
>> $100,000
>> process. Costs you about the same as an expensive lawyer, but it all
>> depends on how many questions you have.
>> The electrical rules for submarines over-ride the electrical rules for
>> ships.
>> If you were totally familiar with their electrical rules you could
>> wire up a
>> super tanker! A lot in there as they have to cover computerised
>> control.
>> Sean is right about no earths in submarines.
>> The electrical through hulls need to be constructed so that if the
>> cable is
>> sheared off, no water can ingress. I saw a lot of through-hull
>> fittings at
>> UI New Orleans & not all had this ability. I guess if you are building
>> for a
>> predominantly ROV market it isn't so necessary.
>> DNVGL normally have reps at UI. I spent quite a bit of time picking
>> their
>> brains when I went there.
>> They are flexible in some areas & have a golden rule that no one
>> failure
>> can result in a major event.
>> What sort of batteries have you got?
>> Deep Sea Power & Light have an ABS type certification on their oil
>> compensated
>> battery.
>> http://www.deepsea.com/?s=sea+battery
>> South West Electronics have a compensated lithium battery. They were
>> looking to get type approval from one or more of the big certifiers
>> but I don't
>> know if they did, or whether it's in process.
>> https://www.swe.com/seasafe-subsea-modules/
>> Alan
>> 
>> Sent from my iPad
>> 
>> On 22/10/2017, at 6:11 AM, River Dolfi via Personal_Submersibles
>> <personal_submersibles at psubs.org> wrote:
>> 
>>> Scott and I have been driving ourselves crazy trying to interpret
>>> the DNVGL rules on subsea electrical cables. We think that the
>>> essence of the problem is that DNVGL lacks rules specific to
>>> oil-compensated external battery banks (except being subject to
>>> "approval by the society"), and to the best of our knowledge DNVGL
>>> has yet to certify any submersible with external ambient batteries.
>>> 
>>> One rule in particular is making us scratch our heads.. UWT pt4 ch8
>>> sec2-1.3 states that "All cables in the outer area shall comply with
>>> (cargo ship cable rules section). All cables shall have an EARTHED
>>> braiding or screen around the conductors and be equipped with an
>>> insulating outer sheet." If this is applicable to the main battery
>>> cable, damage could potentially create an incredibly dangerous
>>> ground fault condition where high voltage is passed to the sphere.
>>> While this requirement makes sense for low-voltage electronics who
>>> require protection from electromagnetic interference, it appears to
>>> be nonsense when applied to a high-voltage DC power cable.
>>> 
>>> Thanks,
>>> 
>>> -River J. Dolfi
>> 
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>>> Personal_Submersibles at psubs.org
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>> 
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