Hello Neil,

take a look here:

http://www.isabellenhuette.de/index3.htm

A company which produces 4-wire shunts for almost any application.
Hope this helps...

Regards
Thomas

-----Urspr=FCngliche Nachricht-----
Von: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] Im Auftrag =
von
PicDude
Gesendet: Sonntag, 17. Juli 2005 20:06
An: piclist@mit.edu
Betreff: [EE] Source for current-sense resistors?

I need to measure DC current up to 100A (at 12V) at multiple points and
planning to use the ZXCT1010 current monitor and a sense resistor for thi=
s.

A drop of 100mV or even a bit more is acceptable; few percent error/accur=
acy
preferred.

(a) Calculated ideal is a 0.001-ohm, 10W, 1% sense resistor, or .0005-ohm
5W, but can't find either at the usual sources (Digikey, Mouser, etc).

(b) I can use 4 sense resistors in parallel -- 0.005-ohm, 3W resistors, b=
ut
these add up to ~$6.  Replicating this a few more times adds up fast.

(c) Shunts are and option, but are really expensive ($19 ea. at All
Electronics).

(d) The other option is to use a couple inches of say 10-ga wire, but I'm
not sure how consistent this wire/resistance is.  Google hasn't found me =
any
info on this accuracy.  I do have the option of calibrating these
individually, but without any specific calibration equipment, I'd like to
avoid doing this. =20
I'm also not sure if I should be running 100A through a piece if 10-ga wi=
re.

(e) Finally, I thought of using a PCB trace for this, which is an elegant
solution, but some high-level calcs of 1oz or 2oz copper yield some large
trace sizes -- ~2 inches wide and 5+" long and really high temps.

Any ideas on this?  Or perhaps a source for the ideal sense resistor in (=
a)?

Cheers,
-Neil.


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