Lightning Protection [RE-wrenches]

[Blake Jones]

Wrenches,
 
First question:
I'm looking for some advice and/or comments about lightning protection.
We've installed lots of solar pumping and inverter systems in the hill
regions of Nepal where lightning strikes occur very frequently, especially
during the monsoon season.  We've mainly been using Delta Lightning
Arrestors on the DC array and on the AC side of the inverters;
unfortunately, we still find many systems with severe lightning damage.
I've heard that the lightning arrestors have a limited life which decreases
proportionally to how much they're called into action, so some of these
systems could have been left unprotected after the lightning arrestors gave
out over several seasons.  Other than that, does anyone have any
recommendations/comments regarding lighting protection and/or particular
experiences with this issue?  Anyone have any experience with lighting rods?
There seems to be a lot of debate about how to properly install and ground
lighting rods, and about what kind of protection they're capable of
providing.....
 
Second question:
Also with regards to lightning protection, what are the
advantages/disadvantages of having multiple grounding points in a system?
For example, we recently installed a solar water pumping system with a
grounding point both at the array AND at the pump house (which is a few
hundred meters from the array).  I've heard mixed advice about using only
one grounding point in a system, as nearby lightning strikes can cause huge
voltage differentials along the ground, which can in turn invite large
currents to pass between your grounding points and damage system components.
Was wondering what the wrenches would say about this?
 
Thanks everyone,
Blake Jones
 
 
Sent by:
Eng. Blake "B.J." Jones, Project Advisor
Lotus Energy Pvt. Ltd.  - "Solar and Renewable Energy Systems Manufacturers"
    PO Box 9219
    1249 Thirvam Sadak - 3          
    Bhat Bhateni-5, Kathmandu
    NEPAL
    Tel:  +977 (1) 4 418 203  (Time Zone=GMT+5:45)
    Fax: +977 (1) 4 412 924
<mailto:blake at lotusenergy.com <mailto:blake at lotusenergy.com> >
<http://www.lotusenergy.com <http://www.lotusenergy.com/> >
 

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