Grounded vs. ungrounded thermocouples

ignatz · Apr 12, 2004

I have an ongoing problem with grounded vs. ungrounded thermocouples. I am confused as to when one is appropriate over the other. As a rule I find that I have less trouble with the ungrounded thermocouples and I ground the negative line at the control panel. Can someone provide an overview as to advantages/situations for each style of TC?

As a side note, is there any advantage of RTD over thermocouples? I have never used them.

Thanks for any assistance.

IRstuff · Apr 12, 2004

Platinum resistance thermometers are extremely accurate and are often used as secondary thermometer transfer standards.

TTFN

analogkid2digitalman · Apr 13, 2004

Grounded TC's with a sheath (as opposed to exposed junctions) have the junction in electrical and mechanical contact with the sheath. They are mechanically more rugged and have higher resistance to corrosion and oxidation.

Ungrounded TC's with a sheath have the same advantages as above over exposed junctions. Additionally they provide a better degree of electromagnetic shielding. But they are slower to respond and may have some error in measurement due to conduction and radiation.

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Grounded vs. ungrounded thermocouples

ignatz

Mechanical

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analogkid2digitalman

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