Something that looks like a fuse - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #11  
Old 03-18-2003
Member
 
Join Date: Jul 2000
Posts: 91
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 15
jparker11 is on a distinguished road
Something that looks like a fuse

Gord,
Dissipation is an important function of land based LP systems. As a captive observer on the top of +800 structures at power plants I can report dissipation does occur (4-6" blue arcs at the tips of lightning points). Obviously, discharging a total strike energy does not occur as strikes do happen to these structures (and, yes, lightning does strike twice, three, four....). The LP systems have specific guidelines (for instance, no downcomer change in direction greater than 45 degrees) which are intended to direct the strike away from electrical conductors, motors etc and with eventual dissipation into the ground.

As the system Werner describes contains abrupt changes in direction and termimates at a dubious ground plate, I would be more concerned with blowing a hole in the boat at a most susceptible location!! Think I would dangle a chain around a shroud when things start crackling.

The land systems we install are UL certified and designed in accordance with National Fire Protection Assoc guidelines. But the science behind it is mostly empirical!! The marine designs are probably even more reliant upon witchcraft!!





Reply With Quote Share with Facebook
  #12  
Old 03-18-2003
Junior Member
 
Join Date: Mar 2003
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
wernervdw is on a distinguished road
Something that looks like a fuse

SOLVED....

I received from a colleague owner of a Dufour a part of the manual identifying the part…

“The entire rigging is grounded by a metal strap connecting the forestay chain plate to the keel. Under normal conditions this circuit is cut by a lightning conductor fixed on the strap situated on the hull behind the main bulkhead. … … The circuit is only re-established if there is an electric discharge of high intensity. This allows use of the rigging as antenna.”

OK… at least Dufour tried to do something about lightning discharge. As some of you already stated it is very doubtful that this might work, but it has been identified.

No… I did not contact Dufour about this. The main reason is that the currect Dufour company only bought the name Dufour. It’s not the same company, hence my doubt that they would know.

Next weekend I''ll make a picture of the "lightning conductor" as it has been identified by now. I only don''t know how to post it on this forum...

thanks guys for the feedback
Werner
Antwerp - Belgium

Reply With Quote Share with Facebook
  #13  
Old 03-19-2003
Senior Member
 
Join Date: Dec 2002
Posts: 552
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 12
GordMay is on a distinguished road
Something that looks like a fuse

Werner:
I''m still confused as to this device''s function.
Is it something like a Metal Oxide Varister (MOV) that only conducts at high voltages; thereby establishing a path to ground for (above threshold) lightning energy?

John Parker:
I knew I should stay "out" of this one - too complex to cover properly - BUT ...
The research (I''ve seen) FAILS to indicate that "Early Streamer (Ion) Dissipators" reduce the incidence of lightning strikes on land-based tall structures. The ground path DOES mitigate the dammage caused by lightning strikes.
For 2 good articles see:
IEEE Transactions on Power Delivery, Vol. 13, No 4, October 1998 (Abdul M. Mousa)
and
IEEE Transactions on Electromagnetic Compatibility, Vol. 33, No. 2, May 1991 (Ewan M. Thomson)
It would take thousands of words to describe the actual installation; but (in reply to yours):
45 degree change in direction: Straight conductors (to ground) are preferred; but a 90 deg. bend with a minimum radius of 8" can be accommodated.
Chain around a shroud: The (minimum #6 AWG copper)ground connection to (salt) water should present a minimum of 1 square foot of surface to the water - more is preferable, especially in fresh water. Would, rather suggest connecting a #6 AWG cable to a (min.) 1 square foot x 1/4" ground plate. This could be clamped to the bow chain plate (further from occupants),
Your concerns ("blowing a hole in boat) are well founded, and not simply addressed.
NFPA guidlines are under current review, and mostly address methodes of dammage mitigation, not prevention (which I, and others, believe to be impossible).
Witchcraft? You bet!
Thanks for all the good information & opinion from all.
Respectfully,
Gord

Reply With Quote Share with Facebook
  #14  
Old 03-19-2003
Junior Member
 
Join Date: Mar 2003
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
wernervdw is on a distinguished road
Something that looks like a fuse

Gord,

When looking through the glass tube at the inside of the "lightning conductor" I recognize 2 electrodes, about 3mm apart. I gues that they work as a kind of arc-lamp. When voltages rise above threshold a spark will jump from one electrode to the other, herby making a ‘plasma’ connection where current can flow through. Again as mentioned before it’s doubtful that it would work for real lighning...

The exterior of the device looks like a very thick fuse with terminal-leads.
It’s about 7.5cm(3”) long and 2cm(.8”) thick.

Best regards
Werner
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Truecharge 40+ fuse replacement cabo006 Gear & Maintenance 1 06-28-2005 12:52 PM
Raytheon Radar XX. fer@fer Gear & Maintenance 6 03-03-2005 03:32 AM


All times are GMT -4. The time now is 09:47 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.