thermocouple checking methods

If it was me I'd go the the thermocouple manufacturers website...

But If I had a chart I'd use it...I'd put the thermocouple output into an Ato D converter implemented on a microcontroller, the write a lookup table to give a reading out in degrees c on a 16 charactre 1 line display... mind I happen to have a boeard which has this stuff on it already.

Del

Check Omega Engineering. They have a real good reference on T/C's

If you don't want to make a science project out of it, you can get a USB T/C DAQ module with display software from Measurement Computing inc for less than a bill. Or you can get Omega's smart T/C connector that has the linearization and scaling done in the shell of a typical T/C connector. All you have to do is hook up a DMM or LCD panel meter and read deg f or c or what ever. They are also under a bill.

Manimaran, you possibly mixed something - RTD measurement based on measuring the resistor which can be done by examining the voltage over a resistor when sending a precise current through it. The amount of volts depends on the temperature, the current through the sensor, the base resistance of the sensor at 0 deg C and the type of sensor which determines the tempco and linearity.

Platin sensors are the best because they are very stable and need no linearisation within 0-100°C when your accuracy requirements allow this.
T/C measurement based on voltage measurement of T/C working as an element independant of the line resistance. T/Cs are rather nonlinear so additional care is obligatory, either in hard- or in software.

I Googled thermocouple formulae and got this ar efunda.

Make sure you understand the cold junction concept.

Analog Devices make linearisation and amplification chips to provide a 10mV/°C response, if you need small and cheap.

I do not know why your are talking of RTD when the subject is thermocouple. Keep it aside.

Just visit TC.CO.UK and request for free thermocouple and RTD usage guide. Probably that is the best text book (Though they do not call it so) on thermocouples and RTDs.

This book contains all the info you want and much more than that.

Hi manimaran,

You can use an SPRT (standard platinum resistance thermometer) connected to an Agilent 34420A to measure temperature directly & accurately without calculations. This is not a cheap solution, but consider that time is money.

S