NTC thermistor

[Simon-lee]

Hi Folks,

I’ve been asked to instrument a rig (Its an air conditioning mock-up). Pre-existing on the rig are several Leibherr P/N 764A000-03 temperature sensors.

I have included a photograph and wiring diagram – from my limited understanding these are NTC devices (negative thermistor).

Is it worth me trying to pick up on these devices (as opposed to dropping in a PT100).

Any suggestions how best to do it.

Regards

Si

[GerdW]

Hi Simon,

from this diagram I would guess it's a thermocouple-type sensor.

But why don't you look for some manuals or datasheets of the sensor at the manufacturer website or sales support?

Before exchanging them for other types of sensors you also need to verify the measurement requirements and your hardware equipment...

[Simon-lee]

Hi GerdW,

Thanks for your interest.

Its proven to be very difficult to find any sort of datasheet for this sensor. The original air conditioning system was lifted out of a scrap civilian airliner. (aircraft scrap yards are the best and yes, you can buy second hand jet engines).

Well understandably aircraft manufactures are very protective as to their electronics and why I’m struggling to get much information and would also explain two identical sensors in one unit (dual redundancy)

I tested your suggestion of a thermocouple and I’m not getting any continuity over the pins, this does point at a thermistor but I’m working from home and all my decent multimeter is in work locked down (my Costco one just isn’t up to the job).

So, I’ve put in an order for a professional multimeter and a solder station (the joy of expenses).  

As I don’t know the operating voltages of expected resistance I will just have to wing it.

I will let you know

Regards

Si

[Simon-lee]

Ok, so I believe I have managed to sort this problem out.

 The unit is as suspected a thermistor (NTC “negative temperature coefficient”)

It worked out at about 9.6kΩ, so a nominal 10kΩ thermistor or rather a pair of 10KΩ Thermistors.

Now because of quarantine I have no access to any professional kit, so I raided to kids toys and found an Arduino Kit – Hay presto I have a working temperature readout.

From these forums I guess I should be able to talk to the Arduino in LabVIEW, so that’s the next challenge.

Pic attached :-