'K' type thermocouple wire connecting to meter - a question

C

Charlie+

Guest
I have a meter with K type thermocouple.
The wire welded blob at the measuring tip is discoloured from the
manufacture but apart from that there is no visible insulation at all to
keep the two different alloy wires apart in the fiberglass insulated
sleeve (about 1.5 Meters long) that then goes to the yellow plug that
fits the meter.
I dont understand how the voltage generated in the tip by the two
dissilar alloys can be measured at the meter when the two alloy wires
are touching probably multiple times anywhere along the length of the
connecting wire.
Can anyone explain this? It definitely works but I dont understand it,
the two individual wires definitely have no thin insulation but I
suppose separation could be hidden in the tight weave of the fiberglass
covering somehow but I cant see it! If you pull the fiberglass sleeve
back there is no visible separator of the wires. Anyone have an answer
to this? C+
 
On 4/14/2017 1:23 PM, Charlie+ wrote:
I have a meter with K type thermocouple.
The wire welded blob at the measuring tip is discoloured from the
manufacture but apart from that there is no visible insulation at all to
keep the two different alloy wires apart in the fiberglass insulated
sleeve (about 1.5 Meters long) that then goes to the yellow plug that
fits the meter.
I dont understand how the voltage generated in the tip by the two
dissilar alloys can be measured at the meter when the two alloy wires
are touching probably multiple times anywhere along the length of the
connecting wire.
Can anyone explain this? It definitely works but I dont understand it,
the two individual wires definitely have no thin insulation but I
suppose separation could be hidden in the tight weave of the fiberglass
covering somehow but I cant see it! If you pull the fiberglass sleeve
back there is no visible separator of the wires. Anyone have an answer
to this? C+
Click to expand...
The thermocouple is the fused tip. The wires going from there to the
meter need to be insulated.
 
On Fri, 14 Apr 2017 18:23:51 +0100, Charlie+ <charlie@xxx.net> wrote:

I have a meter with K type thermocouple.
The wire welded blob at the measuring tip is discoloured from the
manufacture but apart from that there is no visible insulation at all to
keep the two different alloy wires apart in the fiberglass insulated
sleeve (about 1.5 Meters long) that then goes to the yellow plug that
fits the meter.
I dont understand how the voltage generated in the tip by the two
dissilar alloys can be measured at the meter when the two alloy wires
are touching probably multiple times anywhere along the length of the
connecting wire.
Can anyone explain this? It definitely works but I dont understand it,
the two individual wires definitely have no thin insulation but I
suppose separation could be hidden in the tight weave of the fiberglass
covering somehow but I cant see it! If you pull the fiberglass sleeve
back there is no visible separator of the wires. Anyone have an answer
to this? C+
Click to expand...

They have to be insulated so there's probably some enamel on one or
both. I've got some with (obvious - blue colored) enamel.
 
On Fri, 14 Apr 2017 14:16:13 -0400, default wrote:

They have to be insulated so there's probably some enamel on one or
both. I've got some with (obvious - blue colored) enamel.
Click to expand...

Yes, the clear enamel is impossible to see and that's probably what
they've used.
 
On Fri, 14 Apr 2017 14:16:13 -0400, default <default@defaulter.net>
wrote as underneath :

On Fri, 14 Apr 2017 18:23:51 +0100, Charlie+ <charlie@xxx.net> wrote:

I have a meter with K type thermocouple.
The wire welded blob at the measuring tip is discoloured from the
manufacture but apart from that there is no visible insulation at all to
keep the two different alloy wires apart in the fiberglass insulated
sleeve (about 1.5 Meters long) that then goes to the yellow plug that
fits the meter.
I dont understand how the voltage generated in the tip by the two
dissilar alloys can be measured at the meter when the two alloy wires
are touching probably multiple times anywhere along the length of the
connecting wire.
Can anyone explain this? It definitely works but I dont understand it,
the two individual wires definitely have no thin insulation but I
suppose separation could be hidden in the tight weave of the fiberglass
covering somehow but I cant see it! If you pull the fiberglass sleeve
back there is no visible separator of the wires. Anyone have an answer
to this? C+

They have to be insulated so there's probably some enamel on one or
both. I've got some with (obvious - blue colored) enamel.
Click to expand...

Thanks folks for replies, these K thermocouples are OK up to 1300C so
enamel would probably not be best choice. I have taken an even closer
look, very difficult to see but they have wrappped one conductor in
glass weave and then wrapped the second conductor to that first one with
a second weave.
Problem solved! The conductors are not insulated in anything that might
be flammable or oxidize, meter tip runs up both bare conductors without
any surface resistance. C+
 
The gas hot water heater cut off about a year ago when there was no real reason to heat water as the cold water was already 30 C.

Nevertheless I pulled out the sensor, bent it away from the flame or scraped some crud off or something, and it worked!

Some rocket scientist at NASA claimed they had developed a material that "wouldn't accept heat" at a high enough temperature.

I'm thinking, that would really sell in The Valley.


Bret Cahill
 
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