On 2013-02-06 9:22 AM, John Ferrell wrote:
> IMHO:
> Measurements of this type are best done with a balanced bridge for accura=
cy.
> However, the most useful information is collected under actual operating=
=20
> conditions.
> I suspect that when you order 5% resistors they are going to be 5% off.=20
> Fortunately, every time I have ordered a number of them they are close=20
> to being matched.

I don't really have a problem with 5% for high currents in the range of
2-10A. For smaller currents, I can swap out the 0.1ohm resistors with
some 1 or 10 ohm 1% resistors.

> Could it be that they do a production run and then sort them?
> On oil cooling:
> All oil cooling is not equal. In the distant past transformer oil was=20
> more efficient than what we use today. I believe it contained dioxin=20
> which is considered a carcinogen. The devices now commonly use mineral=20
> oil which requires more oil for the same application.
> Heat transfer is not a simple science.

I have good quality thermal compound whose thermal conductivity far
surpasses that of oil, and a bunch of large CPU heat sinks and fans
designed to dissipate hundreds of Watts each. And a very cold freezer if
it gets to that point, but I highly doubt that I'll have an issue here.

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.