Send RE-wrenches mailing list submissions to
re-wrenches@lists.re-wrenches.org
To subscribe or unsubscribe via the World Wide Web, visit
http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org
or, via email, send a message with subject or body 'help' to
re-wrenches-requ...@lists.re-wrenches.org
You can reach the person managing the list at
re-wrenches-ow...@lists.re-wrenches.org
When replying, please edit your Subject line so it is more specific
than "Re: Contents of RE-wrenches digest..."
When responding to posts within the Digest, be sure to restore the Subject:
line to the original, and please edit out any extraneous lines from the quoted
message.
Today's Topics:
1. Re: calculating DC voltage line loss (Windy Dankoff)
2. Re: calculating DC voltage line loss (William Miller)
3. Re: calculating DC voltage line loss (Hugh)
----------------------------------------------------------------------
Message: 1
Date: Sat, 20 Feb 2010 14:05:33 -0700
From: Windy Dankoff <windydank...@mac.com>
To: re-wrenches@lists.re-wrenches.org
Subject: Re: [RE-wrenches] calculating DC voltage line loss
Message-ID: <f0fed95d-d30c-4595-aeda-3e551c634...@mac.com>
Content-Type: text/plain; charset="us-ascii"; Format="flowed";
DelSp="yes"
Marco,
Here's another method that you can print to a sheet of paper. I
published this in Home Power in 1989 and it's been widely used ever
since. So it's an unusual approach, but proven to be consistent with
published charts regardless of voltage. It applies to DC and "simple"
AC as you'll see.
http://www.conergy.us/PortalData/3/Resources/products/solar_pumps/pdf/wire_sizing_chart.pdf
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100220/0c2ad72c/attachment-0001.htm>
------------------------------
Message: 2
Date: Sat, 20 Feb 2010 13:50:14 -0800
From: William Miller <will...@millersolar.com>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Subject: Re: [RE-wrenches] calculating DC voltage line loss
Message-ID: <6.0.1.1.2.20100220134923.03b4d...@millersolar.com>
Content-Type: text/plain; charset="us-ascii"; Format="flowed"
Marco:
Installers world wide have commented favorably on the tool we
developed. It can be found
at: http://millersolar.com/resources/resources.html
William Miller
At 11:48 AM 2/20/2010, you wrote:
Content-Type: multipart/related;
boundary="----=_NextPart_000_009E_01CAB211.DC8DF740"
Content-Language: en-us
xmlns:ns0="urn:schemas-microsoft-com:office:smarttags">
Can anyone pass on a good website address that provides the means to
calculate DC line loss over distance?
The ones that I've come across don't allow for entering in whatever you
want as far as specified DC voltage.
Thanks,
marco
f11587.jpg
Marco Mangelsdorf, President
69 Railroad Avenue, A-7
Hilo, Hawai'i 96720
(808) 969-3281, 934-7462 facsimile
<http://www.provisiontechnologies.com>www.provision-solar.com
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.733 / Virus Database: 271.1.1/2699 - Release Date: 02/19/10
23:34:00
Please note new e-mail address and domain:
William Miller
Miller Solar
Voice :805-438-5600
email: will...@millersolar.com
http://millersolar.com
License No. C-10-773985
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100220/aea76463/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: f11587.jpg
Type: application/octet-stream
Size: 5935 bytes
Desc: not available
URL:
<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100220/aea76463/attachment-0001.obj>
------------------------------
Message: 3
Date: Sat, 20 Feb 2010 23:09:51 +0000
From: Hugh <h...@scoraigwind.co.uk>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Subject: Re: [RE-wrenches] calculating DC voltage line loss
Message-ID: <p062309acc7a616496...@[192.168.1.3]>
Content-Type: text/plain; charset="us-ascii" ; format="flowed"
Can anyone pass on a good website address that provides the means to
calculate DC line loss over distance?
I normally just use the resistivity of copper and make an estimate of
the operating temperature. Most of the standard tables that you find
in books assume that the temperature of the copper wire is at the
limit for PVC insulation (around 70 degrees C) but in reality you
will be working much lower (for energy efficiency) and thus have
lower resistance.
As usual it's a lot easier for us with metric units of measure (wires
are sold according to their cross section in square mm) but you can
also do this with AWG. Remember that increasing wire gauge by 3
halves the area, so #6 has half the sectional area, and hence twice
the resistance of #3.
Here are some resistances I worked out for an article in HP magazine
134 (back page basics) using "English" units. But here I am giving
you the figures at 3 different temperatures to emphasise the effects
of temperature:
FEET PER OHM OF TWIN CABLE
=== === === ===
#AWG 0 35 70 degrees C
=== === === ===
0 5,541 4,639 3,989
1 4,394 3,679 3,164
2 3,484 2,917 2,509
3 2,763 2,313 1,989
4 2,191 1,835 1,578
5 1,738 1,455 1,251
6 1,378 1,154 992
7 1,093 915 787
8 867 726 624
9 687 575 495
10 545 456 392
12 343 287 247
=== === === ===
The figures are FEET ONE WAY to make one ohm for a 2-core cable. For
example if you use #8 at an operating temperature of 35C then you get
726 feet of wire run (actually using 1452 feet of actual wire) to
make one ohm.
It's easy to use. Say your current is I and the wire run is L.
Volt-drop will therefore be
V = I x L / 726 (in this case).
Say 10 amps and 100 feet then you will lose 1000/726 = 1.4 volts.
No sense in calculating a string of decimals, since the temperature
is only estimated anyway.
Using this stuff you can build your own spreadsheet or even do the
calcs quickly in your head to a useful level of accuracy once you
have a bit of experience. As I say its a lot easier with metric
units where the wires sizes are multiples of 1 sqmm, and about 28
metres of that stuff is one ohm.
