contactless temp.measurement

[Dejan Durdenic]

I need to measure temperature of the bare copper wire. The wire
moves, so only contactless methods apply. IR pyrometers are not
reliable, due to surface reflections and (possible) small diameter of the
wire.
ANY suggestions wellcome...

regards

Dejan

 

[Spehro Pefhany]

I need to measure temperature of the bare copper wire. The wire
moves, so only contactless methods apply. IR pyrometers are not
reliable, due to surface reflections and (possible) small diameter of the
wire.
ANY suggestions wellcome...

Can you measure the resistance of the wire itself? Failing that, there
are more sophistimicated methods that use fluorescent material painted
onto the target and fibre optics. Not cheap. There are crude/cheap
melt stick methods you might be able to use (but you might have to
view the wire with some appropriate optics to determine the melting).

Best regards,
Spehro Pefhany

 

[John Woodgate]

I read in sci.electronics.design that Dejan Durdenic

I need to measure temperature of the bare copper wire. The wire
moves, so only contactless methods apply. IR pyrometers are not
reliable, due to surface reflections and (possible) small diameter of the
wire.
ANY suggestions wellcome...

Can you measure its resistance? You would need to establish some
calibration, using a non-moving wire and a thermocouple thermometer or
similar.

 

[CFoley1064]

I need to measure temperature of the bare copper wire. The wire

moves, so only contactless methods apply. IR pyrometers are not
reliable, due to surface reflections and (possible) small diameter of the
wire.
ANY suggestions wellcome...

regards

Dejan

Before you give up on contact-type measurement, you may want to consider either
swaging in and/or using thermally conductive adhesive to affix a 34AWG
thermocouple bead to the wire. The 34 AWG T/C wire could move along with your
copper wire, and would not be much of a heat sink if it was done carefully.
You could then use any standard handheld T/C meter (9V battery-operated,
electrically isolated) to read the temp of the wire. This works well for
measuring nichrome wire temp.

The only other method I could suggest would be to infer temp by reading the
voltage drop across the wire while also reading current, inferring resistance,
and then inferring temp -- full of approximations, not too accurate.

Good luck.
Chris

 

[Wieslaw Bicz]

"Dejan Durdenic

I need to measure temperature of the bare copper wire. The wire
moves, so only contactless methods apply. IR pyrometers are not
reliable, due to surface reflections and (possible) small diameter of the
wire.
ANY suggestions wellcome...

regards

Dejan

I would suggest to measure speed of sound in the wire. This depends on the temperature of the wire
and can be made contactless.
But requires some development work.



Wieslaw Bicz

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[Rene Tschaggelar]

:

I would suggest to measure speed of sound in the wire. This depends
on the temperature of the wire
and can be made contactless.
But requires some development work.

Unfortunately the speed of sound also depends on the tension of the wire.
Copper get harder when is is bent, this means the speed also goes
up with increased use of the wire.

Rene

 

[Wieslaw Bicz]

Unfortunately the speed of sound also depends on the tension of the wire.

Copper get harder when is is bent, this means the speed also goes
up with increased use of the wire.

This is partially true, but this (and many other) influences can be excluded
using many methods.
I have proposed this, because I have already some ideas and some experience,
that can be used here.

From my point of view such measurement is realistic, but this will be not a
simple project.

Wieslaw Bicz

---------------========== OPTEL sp. z o.o. ===========---------------
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[Dejan Durdenic]

To make the things more clear - the wire is moving.
Actually, it's the wire production line, where the wire
preheats before being covered with plastic insulation.
So, no contact can be made with the wire. It runs quite
fast - can be a few m/s.

regards

Dejan

 

[Wieslaw Bicz]

"Dejan Durdenic

To make the things more clear - the wire is moving.
Actually, it's the wire production line, where the wire
preheats before being covered with plastic insulation.
So, no contact can be made with the wire. It runs quite
fast - can be a few m/s.

regards

Dejan

I have assumed this and this was the reason, why I have proposed
acoustic method.
It requires development, but resulting device can be relatively simple.

--
Wieslaw Bicz

---------------========== OPTEL sp. z o.o.
===========---------------
------===== R&D: Ultrasonic Technology/Fingerprint Recognition
====------
ul. Otwarta 10a PL 50-212 Wroclaw Tel.:+48 71 3296854 Fax.:+48 71
3296852
--------==== mailto:[email protected] -=- http://www.optel.pl
====-------

 

[Spehro Pefhany]

To make the things more clear - the wire is moving.
Actually, it's the wire production line, where the wire
preheats before being covered with plastic insulation.
So, no contact can be made with the wire. It runs quite
fast - can be a few m/s.

You don't say the diameter of the wire, but if you really need to do
this, I'd look closely at dual-wavelength infrared measurement.

In fact, you can probably get very good control of your process by
just applying a known amount of heat, at a known speed, for a known
diameter of wire.

Best regards,
Spehro Pefhany

 

[Dejan Durdenic]

Are you interested in some kind of co-operation on this problem?
If yes, we can discuss details over e-mail...

regards

Dejan

 

[Dejan Durdenic]

You don't say the diameter of the wire, but if you really need to do
this, I'd look closely at dual-wavelength infrared measurement.

It can be pretty low - and even stranded...

In fact, you can probably get very good control of your process by
just applying a known amount of heat, at a known speed, for a known
diameter of wire.

That's not the problem - the wire is pre-heated via HF inductor, but the
customer wants closed loop regulation of the wire temp. Sorry - the
customer is ALWAYS right

- Dejan

 

[Wieslaw Bicz]

"Dejan Durdenic

Are you interested in some kind of co-operation on this problem?
If yes, we can discuss details over e-mail...

regards

Dejan

Yes, I am interested. We can discuss the possibilities directly.

--
Wieslaw Bicz

---------------========== OPTEL sp. z o.o.
===========---------------
------===== R&D: Ultrasonic Technology/Fingerprint Recognition
====------
ul. Otwarta 10a PL 50-212 Wroclaw Tel.:+48 71 3296854 Fax.:+48 71
3296852
--------==== mailto:[email protected] -=- http://www.optel.pl
====-------

 

[Phil Hobbs]

Dejan Durdenic

It can be pretty low - and even stranded...




That's not the problem - the wire is pre-heated via HF inductor, but the
customer wants closed loop regulation of the wire temp. Sorry - the
customer is ALWAYS right

- Dejan

My suggestion would be to use the schlieren effect--as in mirages. Run
a beam from a diode laser just above the wire, and detect its wiggling
around via a quadrant photocell with differential detection. This will
be independent of the hardness and surface emissivity of the wire, which
the other suggested methods are not. Assuming the air flow near the
wire is laminar, the schlieren effect will depend on the temperature
gradient, which in turn will depend on the rate of conductive heat loss
from the wire. Thus for wire of a given diameter, you'll get a good
wire temperature measurement.


Cheers,

Phil Hobbs

 

[R.Legg]

To make the things more clear - the wire is moving.
Actually, it's the wire production line, where the wire
preheats before being covered with plastic insulation.
So, no contact can be made with the wire. It runs quite
fast - can be a few m/s.

Measure the temperature of the last hardware in contact with the
moving wire; minimize the difference by controlling the environmental
temperature.

RL

 

[Fred]

It can be pretty low - and even stranded...


That's not the problem - the wire is pre-heated via HF inductor, but the
customer wants closed loop regulation of the wire temp. Sorry - the
customer is ALWAYS right

- Dejan

What's the temperature range of interest for this wire?

 

[Dejan Durdenic]

"Dejan Durdenic @zg.htnet.hr>" <dejan.durdenic<remove_this> wrote in message

What's the temperature range of interest for this wire?

100-150 deg.C

- Dejan

 

[Dejan Durdenic]

Measure the temperature of the last hardware in contact with the
moving wire; minimize the difference by controlling the environmental
temperature.

RL

The subject was pretty clear - "contatcless temp. measurement"...

regards

Dejan

 

[Frithiof Andreas Jensen]

"Dejan Durdenic @zg.htnet.hr>" <dejan.durdenic<remove_this> wrote in message

That's not the problem - the wire is pre-heated via HF inductor, but the
customer wants closed loop regulation of the wire temp. Sorry - the
customer is ALWAYS right

Beware: Quite frequently, the customer thinks he/she "needs" something
without understanding the whole package of consequenses. There is
significant commercial risk involved in bastardising a proven product to
implement some "nice to have but only one guy ever wanted it"-misfeature
that the customer will quickly weasel his way out of once the costs become
clear!

 

[Mac]

You don't say the diameter of the wire, but if you really need to do
this, I'd look closely at dual-wavelength infrared measurement.

After reading your post I read up on this a little bit. It sure sounds to
me like the best bet mentioned so far. It is contactless, and doesn't
require the wire to fill the field of view. Emissivity is less of a
problem with the dual wavelength setup than with single wavelength
techniques. And I don't see why reflections can't be eliminated as a
problem with proper shading of the measurement area.

In fact, you can probably get very good control of your process by
just applying a known amount of heat, at a known speed, for a known
diameter of wire.

Best regards,
Spehro Pefhany

Mac