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<DIV><FONT face=Arial size=2>Kent et al,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Regarding different earth ground
potentials, the local electric utility company recently participated
in the annual spring home show, this year's effort by that
utility continued the green hype labeled Pure Power, but the new event
was a high voltage safety demo aimed at adults as well as kids. What the
enterprising independent contractor (a
former utility lineman) presenting from the well
equipped three booth wide demo pointed out (among other
things) was, in the event of a down high voltage
transmission wire coming into contact with your car, the safest place was
(to remain) in your car. Only when the car was energized _and_ on fire
should you try to exit. Here is the key if you survived this far and a big
surprise to me: If you expected to survive exiting the car and "walking" away,
you should remember to "bunny hop" (keep your feet together) while you
hopped your way from out of the car to a good distance away. He pointed out
that the distance between your steps, should you choose to "walk" away, would be
between different earth potentials high enough to kill you. Sobering
stuff.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>How far to hop he did not define and I did not ask.
My take away-don't loose your balance while hopping or receive
the same unwelcome results as walking. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Bill Loesch<BR>Solar 1 - Saint Louis
Solar<BR></FONT></DIV>
<DIV><FONT face=Arial size=2></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=kent@coveoregon.com href="mailto:kent@coveoregon.com">Kent
Osterberg</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=Allan@positiveenergysolar.com
href="mailto:Allan@positiveenergysolar.com">Allan@positiveenergysolar.com</A>
; <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> Saturday, March 19, 2011 7:25
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [RE-wrenches]
Electromagnetic Pulse (EMP)</DIV>
<DIV><BR></DIV>Allan,<BR><BR>It isn't easy to find the rational info about
this topic amongst the mountain of irrational scare and hype.<BR>Consider
reading about solar disturbances on <A
href="http://news.nationalgeographic.com/news/2011/03/110302-solar-flares-sun-storms-earth-danger-carrington-event-science/">National
Geograpic News</A> and <A
href="http://en.wikipedia.org/wiki/Geomagnetic_storm">Geomagnetic storms on
Wikipedia</A>.<BR>Then read a little about nuclear blast EMP on <A
href="http://en.wikipedia.org/wiki/Electromagnetic_pulse">Wikipedia</A> or
many other places.<BR>Shake this together and you start to reach the scare and
hype that shows up on survivalist blogs.<BR>Yes, it is possible for there to
be problems. Power and communication systems have been disrupted by
geomagnetic storms before. Power and communication systems will have trouble
again. Homeowner inverter systems probably won't have any trouble at least not
any serious trouble. Yet you can't rule out the possibility that some of them
will experience some sort of damage. <BR><BR>Communication systems depending
on radio wave propagation will certainly experience interference. Some
frequencies will be worse than others. Since intense radio interference can
cause electronic devices to misoperate, inverters are potentially at risk
too. Since the corneal mass ejection, CME, arrives a couple days after
the visible solar flare, there is time to prepare and it would be wise to shut
things down for the arrival of the CME. IMHO, the risk to solar or battery
based inverter from a solar burst is not very great.<BR><BR>Wire based
communication systems, pipe line systems, and electric power systems are
exposed to telluric or earth currents, see <A
href="http://en.wikipedia.org/wiki/Telluric_current">telluric current on
Wikipedia</A>. To understand why these are a problem, a couple popular
misconceptions about earth must be corrected: 1) the earth isn't zero
resistance 2) the earth potential isn't the same everywhere. Even copper which
is a much better conductor than the earth has resistance! The earth is more
akin to large piece of inhomogenous resistive material that we make
connections to by poking electrodes into it; much like the doctor sticks
electrodes on your chest and back for an EKG. And current flows through this
huge resistor system: telluric current, galvanic current, current from
cathodic protection systems, current from some electric power systems. So the
earth can't possibly all be the same potential. Now take two grounding
electrodes that are many miles apart: they certainly are a different
potential. If connected by a conductor, current will flow through it - usually
just a small current. In an EMP event, the telluric current can suddenly and
dramatically change. Possibly change to damaging quantities but more often in
a manner that causes power system protection relays to trip lines off
unnecessarily. Consider two grounding electrodes a few hundred feet apart -
the telluric current isn't likely to be large enough to cause any
problem.<BR><BR>No electronic communication means no banking, no commerce, no
police or fire protection, no internet. By gosh it could be the end of society
as we know it. Sell the survivalist a spare inverter and charge controller
(all sales final - no returns allowed - because they will probably want to
return it after the solar maximum).<BR><BR>Kent Osterberg<BR>Blue Moutain
Solar, Inc<BR><BR><BR><BR><BR>Allan Sindelar wrote:
<BLOCKQUOTE cite=mid:4D84EEBF.1090507@positiveenergysolar.com
type="cite">For those of us less aware of solar flare issues and what we
might expect that relates to PV, could someone provide a good link to
educate us?<BR>Thanks, Allan<BR><BR>
<DIV class=moz-signature><FONT face="Times New Roman, Times, serif"><B>Allan
Sindelar</B></FONT><BR><SMALL><A href="mailto:Allan@positiveenergysolar.com"
moz-do-not-send="true"><FONT face="Times New Roman, Times, serif"
color=#000099><U>Allan@positiveenergysolar.com</U></FONT></A></SMALL><FONT
face="Times New Roman, Times, serif"><BR><SPAN
style="FONT-SIZE: 10pt">NABCEP Certified Photovoltaic Installer<BR>NABCEP
Certified Technical Sales Professional<BR>New Mexico EE98J Journeyman
Electrician<BR><B>Positive Energy, Inc.</B><BR>3201 Calle Marie<BR>Santa Fe,
New Mexico 87507<BR><B>505 424-1112</B><BR><A
href="http://www.positiveenergysolar.com/" target=_blank
moz-do-not-send="true"><U>www.positiveenergysolar.com</U></A><O:P></O:P></SPAN></FONT>
<P class=MsoNormal style="MARGIN-RIGHT: 722.25pt"><SPAN
style="FONT-SIZE: 10pt"><FONT
face="Times New Roman, Times,
serif"><ST1:PLACE
w:st="on"><ST1:CITY w:st="on"></ST1:CITY><ST1:STATE
w:st="on"></ST1:STATE><ST1:POSTALCODE
w:st="on"></ST1:POSTALCODE></ST1:PLACE></FONT><B><BR></B></SPAN></P><SPAN
style="FONT-SIZE: 10pt"><BR></SPAN></DIV><BR>On 3/19/2011 11:48 AM, R Ray
Walters wrote:
<BLOCKQUOTE cite=mid:2E505306-9D57-42A2-802E-95CA6C798920@solarray.com
type="cite">Hi Drake;
<DIV><BR></DIV>
<DIV>No, I don't have answers, just more of your same concerns. I had a
high altitude (12,500 ft) installation damaged recently, possibly by a
solar flare in Feb; we lost a C40 charge controller. </DIV>
<DIV>At this point, I don't know if the flare was the cause or not, but I
would expect more problems at higher altitudes.</DIV>
<DIV>So far, my internet research says that the panels and batteries would
be ok, but we might expect damage to electronics similar to the induced
high voltages caused by lightning.</DIV>
<DIV>Would grounding help? (I, too, also considered the Faraday
cage....)</DIV>
<DIV><BR></DIV>
<DIV>NASA is predicting the solar storm of a generation for 2012-2013,
and I read of a similar EMP incident in the 1800s that set telegraph
equipment on fire. </DIV>
<DIV>I think very long utility lines and transformers at the ends of those
lines are the most vulnerable, so this could be more of GridTie
issue?</DIV>
<DIV><BR></DIV>
<DIV>
<DIV><SPAN class=Apple-style-span
style="WORD-SPACING: 0px; FONT: 12px Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; border-spacing: 0px; orphans: 2; widows: 2">
<DIV>R. Walters</DIV>
<DIV><A href="mailto:ray@solarray.com"
moz-do-not-send="true">ray@solarray.com</A></DIV>
<DIV>Solar Engineer</DIV>
<DIV><BR class=khtml-block-placeholder></DIV>
<DIV><BR class=khtml-block-placeholder></DIV><BR
class=Apple-interchange-newline></SPAN></DIV><BR>
<DIV>
<DIV>On Mar 19, 2011, at 8:53 AM, Drake wrote:</DIV><BR
class=Apple-interchange-newline>
<BLOCKQUOTE type="cite">
<DIV>Hello Wrenches,<BR><BR>I had an inquiry concerning the effect of
EMP on photovoltaic systems. We are heading for a period of solar
activity that likely will produce this effect. According to a
local AEP (American Electric Power) representative, the utility is
spending a lot of money to counter this anticipated problem.
Additionally, nuclear related issues are moving back to the front
burner. <BR><BR>It is clear that the pulse would damage an
inverter, but possibly it could be put in a Faraday cage. But a
number of questions arise.
<UL>
<LI>Would the pulse damage the modules?
<LI>Could the large currents and voltages induced by EMP damage the
conductors in the cells?
<LI>Even if the inverters were surrounded by a Faraday cage, would
induced currents & voltages from the modules harm the
inverters?
<UL>
<LI>Would series fuses and surge protectors be adequate protection.
</LI></UL></LI></UL>Has any research been done in this area? Does
anyone know answers to any of these
questions?<BR><BR>Thanks,<BR><BR>Drake <BR><BR><X-SIGSEP></X-SIGSEP>
<P><FONT color=#0000ff>Drake
Chamberlin<X-TAB> </X-TAB>
<BR>Athens Electric<BR>OH License
44810<X-TAB> </X-TAB><BR>CO
license 3773<BR>NABCEP Certified
PV<BR></FONT></P></DIV></BLOCKQUOTE></DIV></DIV></BLOCKQUOTE><BR></BLOCKQUOTE>
<P>
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