Lightning arrestors [RE-wrenches]

Tue Mar 11 13:18:27 PST 2003

Robert:

I just wanted to clarify one point on the Sunny Boys and surge
arrestors.
The European Sunny Boys include fused surge arrestors on the dc input
side.
This was done to meet the requirements for a large European project.
Based on out testing we see no measurable difference in failure rates
for units with and without dc surge arrestors >>IF<< "the dc runs are
kept to a minimum".  This is why we suggest mounting the inverter near
the array.  

The US units do not include dc arrestors.  We have only seen a couple of
inverters with what we think are lightning damage and it is impossible
for us to say if the surge came from the dc or ac sides.  In lightning
prone areas we are more concerned about surges from the ac side and
suggest whole house surge arrestors mounted at the utility service
location.  WWSA's are manufactured by several major suppliers including
GE, Square D, Siemens, Crouse hinds, etc.  Take your pick based on cost,
the type of panel you have, and the "warranty for protected equipment". 

I would also suggest the WWSA for SW's since they have very minimal
filtering on the ac side, no surge arrestors, and a history of problems
with surges coming in on the ac side. The cost for these arrestors is
less than $200 and is therefore pretty cheap insurance (IMHO of course).

If you have any questions or if I may be of any further assistance,
please do not hesitate to contact me.

Best Regards,

John Berdner

SMA America, Inc.
12438-C Loma Rica Road
Grass Valley, CA  95945
530.273.4595 - Tel
530.274.7271 - Fax

-----Original Message-----
From: Robert Warren [mailto:robertwarren at mail.com] 
Sent: Monday, March 10, 2003 11:30 PM
To: RE-wrenches at topica.com
Subject: Lightning arrestors [RE-wrenches]

I just recently had to replace the AC control boards on two paralleled 
Trace SW4548E inverters because Xantrex would not warranty them, even 
though they were only halfway into their two year warranty period. This 
repair cost me nearly as much as the price of one new inverter! 
They said, "because the same fault was found on both inverters, it was 
likely an external cause." Now, both inverters were still working as far

as inverting: it was the battery charger mode which was bad. First clue 
was that the internal LCD meter showed 0 VAC output when the inverter 
was really putting out 228 VAC. So if the inverter didn't know if it was

producing any power, how could it synchronize to the generator when it 
started?
 I think it is really bad news for dealers that there is no internal 
surge protection inside these inverters. Sunnyboy inverters have a bank 
of MOV's and multi-path surge protection, as far as I know. 
  The technie I talked to on the help line said that the particular 
chip, T5, could have been damaged by a spike or a high demand. This 
could have been lighting, or could have been a spike from the gen set.
Since the Trace inverters have both software and hardware overcurrent 
protection, this led me to believe it was a spike. Further analysis 
before sparking them up again revealed a corroded through grounding 
clamp bolt. Everything was properly earthed to a single point grounding 
system when installed, but I think there was still a bit of ground-loop 
current between the house and the barn, where the generator sits, 
accelerated the di-electric effect on this brass bolt. Once the closest 
Earth to the generator was lost (even though it had another oversized 
grounding wire back to the main earthing rod for the inverters) the 
genny was likely throwing out spikes. 
 I just hate lifting those heavy Trace monsters up on the wall, and 
don't want to do all this again!  So I installed a couple of lightning 
surge suppressors parallel to the AC2 input to protect the inverters 
from the diesal generators, and another on the AC out circuit, just in 
case I get an induced lightning spike coming back from the house. 
Robert Warren
robert.warren at solarcentury.co.uk
www.solarcentury.c.uk

What will we do if there is another fuel shortage? 
Did you know that there is a pollution free, completely
renewable fuel which you can use right now in your own car? 
Don't replace the engine, replace the fuel.
Check out my website on making your own fuel: 
http://running_on_alcohol.tripod.com 
robertwarren at mail.com

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