On 01/01/2013 20:19, wrote:
As part of another project, would like to take some High Current DC measurements.

I have a couple of multimeters ... but obviously not going to be any good for around 80-100A

Now going back to school physics lessons I could use a Shunt resistor ...
http://www.societyofrobots.com/robot...?topic=13900.0

The issue will be obtaining a suitable shunt ... assuming I use a 1 ohm shunt, anybody made one of these ?
The WEB ref page:http://www3.zetatalk.com/docs/Electr...Meter_2007.pdf
details using 12guage copper wire .. based on 1.619 ohm per 1000'

A 1R shunt will drop 100V at 100A and have to dissipate 10kW!
Even a 0.01R dropping 1V will need to handle 100W at 100A without
getting too warm (and so altering its own resistance). Forced air
ventilation on a chunky heatsink would seem to be the best bet.

You would be much better off buying a 10x high power 0.1R resistors and
a suitably large aluminium heatsink.

Are you absolutely sure you want to do this ? You don't sound at all
safe. 10 of these on a decent heat sink ought to just about hack it.

http://www.rapidonline.com/Electroni...sistor-62-8071

ISTR Zetatalk is a bunch of delusional nutters led by "Nancy" that
expected the world to end around 1996 when the "Radish" planet X
arrived. World ending cults go quiet for a while after it doesn't.

Yes.
Indeed it is the same bunch of delusional nutters see the home page:

http://www3.zetatalk.com/

Unless you want to be first in line for a Darwin Award you would do well
to ignore anything they say on that site!

Although maybe a resistance wire may be better eg Nichrome around 10.58" for 1 ohm.
Welcome to any better ideas.

http://www.rapidonline.com/Electroni...esistors-79897

But nothing with the sort of power handling rating you would want.

--
Regards,
Martin Brown