Mailing List flyrotary@lancaironline.net Message #33936
From: Ernest Christley <echristley@nc.rr.com>
Subject: Re: [FlyRotary] Musings on the EM-2 connector P1
Date: Wed, 11 Oct 2006 08:50:52 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Bill Bradburry wrote:

I have been slowly building the harnesses for the EC and EM-2.  I now
have arrived at the P1 connector on the EM-2.  This supplied connector
is a solder connector to be connected to J and K thermocouple
wire....Hmmm.  You can not solder this wire....Hmmm.
I have considered buying a crimp connector, BUT there is going to be a
transition joint from thermocouple wire to copper at some place inside
this apparatus no matter what you do.
So what I am going to do is make up copper jumpers that solder to the
connector and terminate with crimped ring terminals for connection to
the thermocouple wires.  The connection will be inside the panel and I
think will introduce a minimum of error in the system.
Any comments or a better way to think of this?

Bill Bradburry

 

Thermocouples produce a voltage by having to dissimilar wires in intimate contact.  The polarity of the voltage is determined by the metals.  The size of the voltage is determined by the temperature.  Adding coppy wire introduces a third dissimilar metal, which screws up everything, BUT...

You connect the copper at one end and you produce a positive voltage change.  Then you put copper at the other end, and you produce a negative voltage change.  As long as the temperature of the copper junctions are the same, the voltage will be the same...but opposite. At least, that is how I understand it.

--
        ,|"|"|,              Ernest Christley       |
----===<{{(oQo)}}>===----    Dyke Delta Builder      |
       o|  d  |o        http://ernest.isa-geek.org  |
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