Michael Ross wrote:
Dielectric essentially means non-conductive. The whole point of NoAlOx is
to enhance conductivity and it contains zinc powder - some one said (I
haven't looked into it much).
Theoretically, why would you want to put a non-conductive material between
two current carrying members, when a conductive grease would do just as
well at protecting from moisture? I see no reason not to smear dielectric
all around outside, but it might end up in the current path just the same.
No "conductive" grease is even remotely as conductive as metals. Their
resistivity is many orders of magnitude higher.
Zinc is widely used as a sacrificial metal to protect other metals from
galvanic corrosion. The zinc corrodes before the base metal.
An electrical contact may appear smooth, but microscopically has many
high and low points. Only the high points touch. The purpose of high
contact pressure is to "crush" these high points, to get more surface area.
The purpose of contact "greases" is to seal the spaces between the
conductors that don't touch, so that water, air, and other contaminants
can't get in. If they do, they form corrosion products which are bigger
than the metals they replace. As the corrosion grows, it forces the
contacts apart, and connection eventually fails.
The pressure on the tiny points of actual contact is so high that it
squeezes out the grease.
--
Engineers like to solve problems. If there are no problems handily
available, they will create their own problems. -- Scott Adams
--
Lee Hart -- See my Xmas projects at www.sunrise-ev.com/projects.htm
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