<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML xmlns="http://www.w3.org/TR/REC-html40" xmlns:v =
"urn:schemas-microsoft-com:vml" xmlns:o =
"urn:schemas-microsoft-com:office:office" xmlns:w =
"urn:schemas-microsoft-com:office:word" xmlns:m =
"http://schemas.microsoft.com/office/2004/12/omml"><HEAD>
<META http-equiv=Content-Type content="text/html; charset=gb2312">
<META content="MSHTML 6.00.2900.5764" name=GENERATOR>
<STYLE>@font-face {
font-family: Cambria Math;
}
@font-face {
font-family: Calibri;
}
@font-face {
font-family: Tahoma;
}
@page Section1 {size: 8.5in 11.0in; margin: 1.0in 1.0in 1.0in 1.0in; }
P.MsoNormal {
FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman","serif"
}
LI.MsoNormal {
FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman","serif"
}
DIV.MsoNormal {
FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman","serif"
}
A:link {
COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99
}
SPAN.MsoHyperlink {
COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99
}
A:visited {
COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99
}
SPAN.MsoHyperlinkFollowed {
COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99
}
P.MsoAcetate {
FONT-SIZE: 8pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Tahoma","sans-serif"; mso-style-priority: 99; mso-style-link: "Balloon Text Char"
}
LI.MsoAcetate {
FONT-SIZE: 8pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Tahoma","sans-serif"; mso-style-priority: 99; mso-style-link: "Balloon Text Char"
}
DIV.MsoAcetate {
FONT-SIZE: 8pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Tahoma","sans-serif"; mso-style-priority: 99; mso-style-link: "Balloon Text Char"
}
SPAN.EmailStyle17 {
COLOR: #1f497d; FONT-FAMILY: "Calibri","sans-serif"; mso-style-type: personal
}
SPAN.EmailStyle18 {
COLOR: #1f497d; FONT-FAMILY: "Calibri","sans-serif"; mso-style-type: personal-reply
}
SPAN.BalloonTextChar {
FONT-FAMILY: "Tahoma","sans-serif"; mso-style-priority: 99; mso-style-link: "Balloon Text"; mso-style-name: "Balloon Text Char"
}
..MsoChpDefault {
FONT-SIZE: 10pt; mso-style-type: export-only
}
DIV.Section1 {
page: Section1
}
</STYLE>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></HEAD>
<BODY lang=EN-US vLink=purple link=blue bgColor=#ffffff>
<DIV><FONT face=Arial size=2>Hello Matt,</FONT></DIV>
<DIV><FONT face=Arial size=2>All UL modules or panels with accessible metal
parts are rquired to be production line factory dielectric
voltage-withstand tested for 1 minute without electrical breakdown at 2
times maximum system dc voltage plus 1,000 volts (UL 1703, Section
43).</FONT></DIV>
<DIV><FONT face=Arial size=2>Joel Davidson</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=gilligan06@gmail.com href="mailto:gilligan06@gmail.com">Matt
Lafferty</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=re-wrenches@lists.re-wrenches.org
href="mailto:re-wrenches@lists.re-wrenches.org">'RE-wrenches'</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, April 28, 2009 12:48
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [RE-wrenches] To Megger or
not to Megger</DIV>
<DIV><BR></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Hi Bill,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>I so totally agree with your comment about the price
of these being a non-issue, all things considered. As long as we're getting
the features we need in the sub-$750 range, that is. When it comes
down to it, this is meaningful safety and reliability stuff. No slam to the
Bolinas crew, but the SunEye is a lettle less important than that. Unless, of
course, you shade a certain type of module and the bypass diode fails and the
thing ignites.... Then you could make a case for the SunEye being prudent for
Disqualification of location, which would mean there wouldn't be a need for
the megger on that non-job.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Perhaps you could address a couple of aspects that I have
questioned for a long time.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>First of all, is it or is it not true that megger testing
an array at 1kV may result in flaky-bias diodes <EM>(my
term)</EM> if polarity of test leads is incorrect relative the array
and/or the array wiring is grounded/not grounded during the test?
<EM>(The root of my policy to NOT megger arrays unless I have specific
procedure provided by the mfr... Me no wanna get in a "you meggered it so you
don't have a warranty" conversation if ya know of what I
speak.)</EM></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Which of the mainstream module manufacturers are
publishing a procedure for megger testing their arrays for use by
installers?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Are these being published for wet or dry testing?
Both?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Which of these manufacturers are supplying this
documentation in a publicly accessible manner? <EM>(Asked quite a few sales
reps over the years and only 1 ever produced a document... I have been
able to get some from engineers in the factory, but this was generally when I
had a big stick to pound on somebody's desk.) </EM></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Why don't most installers and distributors know this
documentation exists or understand the procedure at this
point?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Yeah, it's one of those thorny issues with me. Maybe
we can get our heads together to steamroll a solution to the above. Happy to
take the subject up off-list if you like.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>On to today's question regarding resolution....
</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>When you are measuring an array, why is the resolution so
critical?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>What value or value range do you believe constitutes
a Pass on a quality Csi product?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>How about Asi / CdTe with crappy
glass?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>How about Asi with Tefcel?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN><SPAN class=671005117-28042009><FONT
face=Arial color=#0000ff size=2>Wet? Dry?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Does your answer change relative the capacity of the
array portion under test?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Does the answer change with temperature &/or relative
humidity?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Does the answer change relative test voltage compared to
array VOC?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>What I'm getting at is, unless the minimum "Pass"
value is a very low number for the test setup, say 200K -
2M, or has a very narrow "Pass" range, </FONT></SPAN><SPAN
class=671005117-28042009><FONT face=Arial color=#0000ff size=2>a super-fine
resolution shouldn't be that critical. On the few occasions back in the
day when I actually meggered arrays, I used an analog megger. Top end
range @ 1kV was 250M. My recollection is that these things pulled 15M or
better, but I can't really testify to that... Fuzzy memory on the actual
values. I'd have to dig through some deep stacks of paperwork to find out if I
have any archives of the tests, and I'm not gonna do that for this post.
Had to submit the test results to SMUD (can't find them) and the mfrs. Nobody
ever said, "<EM>Hey. Close your other eye and tell me what it says."</EM> When
I asked what values would be appropriate, all I ever got was, <EM>"Just like
you got here. These are good."</EM> Never could nail them down and, frankly,
never got the idea that they were all-to-happy having installers owning
meggers.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>I'm with you on testing the array and module
interconnects for leakage. Really. But, if the arrays rings out as "faulted"
when it's really "OK", why bother? What are you looking for? If the resistance
is that low, maybe we should be using a "Kohmer" for the arrays and a Megger
for the wiring & equpment bussing. If you're getting such a low
resistance, aren't you picking it up with a "Static" test...
</FONT></SPAN><SPAN class=671005117-28042009><FONT face=Arial color=#0000ff
size=2>Would the Earth Bond Resistance function of the 1507 & 1503 be
sufficient for these situations? <A
href="http://us.fluke.com/usen/products/specifications.htm?cs_id=35391(FlukeProducts)&category=HMA(FlukeProducts">http://us.fluke.com/usen/products/specifications.htm?cs_id=35391(FlukeProducts)&category=HMA(FlukeProducts</A>)
This is basically a voltage shot like a megger, but measures resistance in the
<20k range. Resolution very nice there! </FONT></SPAN><SPAN
class=671005117-28042009><FONT face=Arial color=#0000ff size=2>This tester has
a gap between 20k & 100k (0.1M). </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>From a "reasonable resolution" perspective, I think the
gap is more like 20k to 2M. Anything over 2M, the 0.1M resolution should be
fine. If the array is that close to failing, fail it and tell the mfr to start
making some decent glass. They might understand it better this way:
<FONT face="Times New Roman" color=#000000
size=3>ÄúÎü</FONT></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Dunno. I think it comes down to figuring out what ranges
equal "Pass" for the application and going from there. Will look forward
to what you find in your side-by-sides later this week. Please do post back.
With a basic description of the glass-type, mounting, wire-management, test
results and findings, if you can.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>I'm gonna hang onto my 1520... If anybody wants to see
what one looks like with a 100% Battery Level, let me know... I'll hold it up
in front of my webcam for ya!</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009></SPAN><SPAN
class=671005117-28042009></SPAN><SPAN class=671005117-28042009></SPAN><SPAN
class=671005117-28042009></SPAN><SPAN class=671005117-28042009></SPAN><SPAN
class=671005117-28042009></SPAN><SPAN class=671005117-28042009><FONT
face=Arial color=#0000ff size=2>No Ground Faults!</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=671005117-28042009><FONT face=Arial
color=#0000ff size=2>Matt
Lafferty</FONT></SPAN></DIV><BR></BLOCKQUOTE></BODY></HTML>