High-temperature thermocouple indication issue
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I have seen high-temperature thermocouples with a range of 0-1800 that could display values properly, and the high-temperature thermocouples being used now have a range of 100-1600 and can also indicate values correctly. Why is the range not 0 but 100?
The display instrument shows the temperature based on the type of thermocouple set and the measured millivolt value; it has little to do with the set range, except in cases of temperature changes.
K-type thermocouple, with a transmitter in between.
Is this one of those thermocouples? ? It’s best to check the relationship between temperature and millivolts; in some cases, there are no millivolts below 100 degrees
Why does this happen? Why do some have a value of less than 100 while others don’t?
“A K-type thermocouple with a transmitter in between means that the 4–20mA signal output by the transmitter corresponds to temperatures of 100–1600°C. The advantage of this setup is that it makes it easy to detect a broken thermocouple; when the thermocouple is broken, the input terminal of the transmitter reads 0mV, and the transmitter’s output will be less than 4mA, resulting in a reading below 100°C, which allows for an initial determination that the thermocouple is broken.
For example, a Type B thermocouple has a thermoelectric potential of 0.033 millivolts at 100 degrees. It’s impossible to measure such a small value; what type of thermocouple do you have? ? ? Also, what components are used in the entire circuit: is it connected to a safety barrier, to a card, or through a 4-20MA transmitter? ?
It depends on the type. If temperature compensation is applied, it operates according to the range; if it’s simply incorporated into a template, then the range of the thermocouple doesn’t matter much