Date: Wed, 10 Jun 2009 13:44:48 -0400
Reply-To: VW Doka <vw.doka@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: VW Doka <vw.doka@GMAIL.COM>
Subject: Re: Correct use of Dielectric grease?
In-Reply-To: <Pine.LNX.4.64.0906101256450.17312@goldenaxe.gpcc.itd.umich.edu>
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Good explantion.... but "springyness"?
IIRC, quite a few Japanese cars came with gobs of grease (a
brown/orange color) in the light sockets for the tail lights and turn
signals. I've seen this on a few other mfgs. as well.
It's a nice add-on for those pesky, love to rust, front turn signal
sockets on the Vanagons.
Cheers,
Jeff
On Wed, Jun 10, 2009 at 1:22 PM, Jonathan Farrugia<jfarrugi@umich.edu> wrote:
> dielectric grease is used in layman's terms to prevent dielectric
> corrosion. that is corrosion between two dissimilar metals that have
> different voltages of reduction (that is a physic/chemistry term). when
> dissimilar metals have different reduction voltages one can oxidize the
> other, oxidation is what is commonly referred to as corrosion. in
> addition to oxidation by other metals oxidation can occur from other
> atomic elements such as chlorine as is the case with salt compounds.
>
> if oxygen is excluded from the metals by the use of a coating whether that
> be paint or grease no oxidation can occur. that is why dielectric grease
> is used.
>
> okay onto the part of the question that asked about electrical connections
> being hindered by the grease. all electrical connections rely on physical
> contact ie pressure to work. the 'best' electrical connection in simple
> terms could be thought of as a bolted connection. that connection type
> gives very high pressures, most hight voltage stuff is of the bolted
> connection type. a bolted connection is not always practical in economic
> or physical terms. another method of electrical connection is a spring
> type connection.
>
> if you have ever been in a circuit breaker box that doesn't use screw and
> the breakers just pop in it is because a spring finger type connection
> system is being used. push type connectors used in the vanagon system are
> of the same spring design. lets take the case of a normal 1/4" male and
> female blade connector. the male part is of a fixed dimension. the
> female part is constructed from a spring type material. when you push the
> two together the female part made of spring material expands over the male
> blade. the connection here is made metal to metal with the pressure
> provided by the spring. the spring is the sole clamping force for this
> connection. if you have adequate force by design at your connection it
> will be strong enough to displace any grease and the metal to metal
> connection will be made.
>
> spring connectors are subject to problems when exposed to high heat. this
> is why it is bad to reuse connections that have been overheated
> electrically. the heating changes the springyness of the connector and
> thus the clamping force of the connection is reduced. this often can lead
> to a poor/loose connection and arcing at the connection site.
>
> those are my thoughts for what they are worth please take them as a
> starting point for your further research.
>
> jonathan
>
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