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From: JW on 8 Jul 2010 07:36
On Wed, 07 Jul 2010 11:40:15 -0700 John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in Message id:
<19i936d8s89amglk2ohfdgqei711nga6fg(a)4ax.com>:

>Shunts usually self-heat, which adds a nonlinearity to the power
>measurement. So it's worth getting ones with a low TC.

Why not use a 4 wire shunt?
From: John Larkin on 8 Jul 2010 09:54
On Thu, 08 Jul 2010 07:36:08 -0400, JW <none(a)dev.null> wrote:

>On Wed, 07 Jul 2010 11:40:15 -0700 John Larkin
><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in Message id:
><19i936d8s89amglk2ohfdgqei711nga6fg(a)4ax.com>:
>
>>Shunts usually self-heat, which adds a nonlinearity to the power
>>measurement. So it's worth getting ones with a low TC.
>
>Why not use a 4 wire shunt?

Sure. But that doesn't help the self-heating/TC problem. If you're
working with DC, you can have thermocouple potential problems, too.

John



From: AM on 8 Jul 2010 10:14
On Thu, 08 Jul 2010 06:54:49 -0700, John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>On Thu, 08 Jul 2010 07:36:08 -0400, JW <none(a)dev.null> wrote:
>
>>On Wed, 07 Jul 2010 11:40:15 -0700 John Larkin
>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in Message id:
>><19i936d8s89amglk2ohfdgqei711nga6fg(a)4ax.com>:
>>
>>>Shunts usually self-heat, which adds a nonlinearity to the power
>>>measurement. So it's worth getting ones with a low TC.
>>
>>Why not use a 4 wire shunt?
>
>Sure. But that doesn't help the self-heating/TC problem. If you're
>working with DC, you can have thermocouple potential problems, too.
>
>John
>
>

Use the "Z" alloy.
From: John Larkin on 8 Jul 2010 10:22
On Thu, 08 Jul 2010 07:14:10 -0700, AM
<thisthatandtheother(a)beherenow.org> wrote:

>On Thu, 08 Jul 2010 06:54:49 -0700, John Larkin
><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>
>>On Thu, 08 Jul 2010 07:36:08 -0400, JW <none(a)dev.null> wrote:
>>
>>>On Wed, 07 Jul 2010 11:40:15 -0700 John Larkin
>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in Message id:
>>><19i936d8s89amglk2ohfdgqei711nga6fg(a)4ax.com>:
>>>
>>>>Shunts usually self-heat, which adds a nonlinearity to the power
>>>>measurement. So it's worth getting ones with a low TC.
>>>
>>>Why not use a 4 wire shunt?
>>
>>Sure. But that doesn't help the self-heating/TC problem. If you're
>>working with DC, you can have thermocouple potential problems, too.
>>
>>John
>>
>>
>
> Use the "Z" alloy.

It's expensive and hard to get, and I don't think we could photo-etch
it.

John

From: Spehro Pefhany on 8 Jul 2010 10:33
On Thu, 08 Jul 2010 07:14:10 -0700, AM
<thisthatandtheother(a)beherenow.org> wrote:

>On Thu, 08 Jul 2010 06:54:49 -0700, John Larkin
><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>
>>On Thu, 08 Jul 2010 07:36:08 -0400, JW <none(a)dev.null> wrote:
>>
>>>On Wed, 07 Jul 2010 11:40:15 -0700 John Larkin
>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in Message id:
>>><19i936d8s89amglk2ohfdgqei711nga6fg(a)4ax.com>:
>>>
>>>>Shunts usually self-heat, which adds a nonlinearity to the power
>>>>measurement. So it's worth getting ones with a low TC.
>>>
>>>Why not use a 4 wire shunt?
>>
>>Sure. But that doesn't help the self-heating/TC problem. If you're
>>working with DC, you can have thermocouple potential problems, too.
>>
>>John
>>
>>
>
> Use the "Z" alloy.

This stuff looks pretty nice:
http://www.isabellenhuette.de/pdf/WIDER_LEG/ZERANIN-ISABELLENHUETTE-R.pdf


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