Electronics > Beginners
Thermocouople thermometers.
schmitt trigger:
I also suggest that you read the white papers available at Omega.com.
They are an excellent information source.
Like every technical decision one makes, one has to make tradeoffs and therefore depending on the particular application, performance requirements and cost, one can make an informed decision.
IanB:
--- Quote from: ahbushnell on December 29, 2018, 04:23:24 pm ---
--- Quote from: Kleinstein on December 26, 2018, 03:11:20 pm ---The usual way is to use compensation with a different type of thermometer.
A special case is a type of Pt based thermocouple. This has very low thermal EMF around room temperature and thus does not care much about the cold junction temperature, but also only works from some 300 C up. So if the cold junction is not too extreme it can get away without compensation.
--- End quote ---
A Pt is not a thermocouple. It is a platinum resistor. They do an excellent job.
--- End quote ---
Why did you disagree with Kleinstein, when they specifically used the word thermocouple in their post?
See the link below and look at "Type B" thermocouples:
http://www.capgo.com/Resources/Temperature/Thermocouple/Thermocouple.html
--- Quote ---Good at high temperatures, no reference junction compensation required.
--- End quote ---
ArthurDent:
I think that the confusion here is that there is a PT100 platinum resistance temperature sensor. It has a resistance of 100 ohms at 0 degrees C and is very linear and accurate and usable to about 500 degree C. The PT thermocouple has two different alloys and does produce a voltage.
beanflying:
Edit removed quotes as I had them jumbled
Kleinsteins "Pt Thermocouple" isn't helpful as it could give the impression to some that it was a Pt only device (so not actually a thermocouple) and the most common of those is the RTD. The Type B, R and S Thermocouples are highly specialized and not common by comparison.
As Arther stated these are Platinum and Rhodium based thermocouples in the link above and as such generate a voltage as distinct from PT100, PT1000 etc. which are just Platinum and vary resistance. Both have pros and cons but that is outside the scope of what the OP was chasing information on.
Link just for information on Resistance Thermometer types https://en.wikipedia.org/wiki/Resistance_thermometer or the Omega site will have more in depth information.
ahbushnell:
--- Quote from: IanB on December 29, 2018, 08:04:34 pm ---
--- Quote from: ahbushnell on December 29, 2018, 04:23:24 pm ---
--- Quote from: Kleinstein on December 26, 2018, 03:11:20 pm ---The usual way is to use compensation with a different type of thermometer.
A special case is a type of Pt based thermocouple. This has very low thermal EMF around room temperature and thus does not care much about the cold junction temperature, but also only works from some 300 C up. So if the cold junction is not too extreme it can get away without compensation.
--- End quote ---
A Pt is not a thermocouple. It is a platinum resistor. They do an excellent job.
--- End quote ---
Why did you disagree with Kleinstein, when they specifically used the word thermocouple in their post?
See the link below and look at "Type B" thermocouples:
http://www.capgo.com/Resources/Temperature/Thermocouple/Thermocouple.html
--- Quote ---Good at high temperatures, no reference junction compensation required.
--- End quote ---
--- End quote ---
Because he was talking about a Pt basted "thermocouple". The Pt term is used for RTD type platinum temperature sensors.
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