TI-30 70 S2 mystery temperature sensor

A

Andre Majorel

Guest
Found in a yoghurt maker whose heating element never turns off :

http://www.teaser.fr/~amajorel/ee/f/ti3070s2.jpg

Black plastic, 23.3 x 6.7 x 3.6 mm with two wires (red and
black) coming out of one end. Marked IT-30 70 S2.

From the shape, it could be a thermocouple or an RTD but I know
nothing about temperature sensors. Does anyone know what it is ?

Thanks in advance !

--
André Majorel http://www.teaser.fr/~amajorel/
It is difficult to get a man to understand something, when his
salary depends upon his not understanding it. -- Upton Sinclair
 
"Andre Majorel" <cheney@halliburton.com> wrote in message
news:slrnmms7n3.2aa.cheney@atc5.vermine.org...
Found in a yoghurt maker whose heating element never turns off :

http://www.teaser.fr/~amajorel/ee/f/ti3070s2.jpg

Black plastic, 23.3 x 6.7 x 3.6 mm with two wires (red and
black) coming out of one end. Marked IT-30 70 S2.

From the shape, it could be a thermocouple or an RTD but I know
nothing about temperature sensors. Does anyone know what it is ?
Click to expand...

I don't know what you have, but here is a quick lesson.

The RTD is a resistor that changes in resistance as it heats up. Almost
always they will go up in resistance as they heat up. The resistance is
around 110 ohms for some at room temperature.

A T/C will generate a small voltage and go higher as it heats up. Around 1
milivolt at room temperature. If you use an ohm meter it will show almost
no resistance. Just whatever the short wires are.

A RTD does not care about the polarity of the wires, a T/C will as it
generates a small DC voltage.
 
On 2015-06-02, Ralph Mowery <rmowery28146@earthlink.net> wrote:

I don't know what you have, but here is a quick lesson.

The RTD is a resistor that changes in resistance as it heats
up. Almost always they will go up in resistance as they heat
up. The resistance is around 110 ohms for some at room
temperature.

A T/C will generate a small voltage and go higher as it heats
up. Around 1 milivolt at room temperature. If you use an ohm
meter it will show almost no resistance. Just whatever the
short wires are.

A RTD does not care about the polarity of the wires, a T/C
will as it generates a small DC voltage.
Click to expand...

Got it, thanks. The fact that the wires are different colours
points towards a thermocouple but the resistance is much too
high (or so I'm told by the person who's trying to repair it).

I'll try my luck on sci.electronics.repair. Someone must have
seen one of those before.

--
André Majorel http://www.teaser.fr/~amajorel/
It is difficult to get a man to understand something, when his
salary depends upon his not understanding it. -- Upton Sinclair
 
On Tue, 2 Jun 2015 21:23:47 +0000 (UTC), the renowned Andre Majorel
<cheney@halliburton.com> wrote:

Found in a yoghurt maker whose heating element never turns off :

http://www.teaser.fr/~amajorel/ee/f/ti3070s2.jpg

Black plastic, 23.3 x 6.7 x 3.6 mm with two wires (red and
black) coming out of one end. Marked IT-30 70 S2.

From the shape, it could be a thermocouple or an RTD but I know
nothing about temperature sensors. Does anyone know what it is ?

Thanks in advance !
Click to expand...

It's an entire thermostat, made by Ka Wo in Dongguan China.

Differential is quite wide (10-35°C). maybe the 70 is the set
temperature. It will switch a few amperes at mains potential directly.

This looks more like an overtemperature cutoff device than a control
device to me, but then I have no idea how a yoghurt maker works.

I would be looking for a different kind of temperature sensor than
this part.

--
Best regards,
Spehro Pefhany
Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8
Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48
 
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