[PSUBS-MAILIST] DNVGL

[Scott Waters via Personal_Submersibles]

Sean,
On a DSV the batteries are in a separate compartment filled with oil. The cables go from the battery box to the hull. My interpretation of the rule is it did not consider this. 
Thank you,Scott Waters


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-------- Original message --------From: "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles at psubs.org> Date: 10/21/17  1:41 PM  (GMT-06:00) To: personal_submersibles at psubs.org Subject: Re: [PSUBS-MAILIST] DNVGL 
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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