Glossary of Temperature Calibration Terms

10-31-2018 | Temperature
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Dry Well Calibrator:

A temperature calibrator that uses a precision oven to source precise temperature. This style of calibrator is often used for the verification of temperature sensors.

Excitation Current:

A constant current applied to an RTD probe to determine actual resistance for temperature measurement. Typical values are 2 mA or less to minimize self-heating of the probe.

IPTS-68:

International Practical Temperature Scale of 1968. A temperature standard adopted in 1968 that uses intrinsic standards to define the measurement of temperature.

ITS-90

International Temperature Scale of 1990. A temperature standard adopted in 1990 that uses intrinsic standards to define the measurement of temperature. This standard modifies the intrinsic standards of IPTS-68 with additional intrinsic references.

Lead Resistance Compensation:

A compensation method used with 3 and 4 wire RTDs and resistance measurement. This method negates the error associated with lead resistance when making an RTD measurement.

Reference Temperature:

The temperature at which a thermocouple temperature measurement is referenced. For Fluke Calibration tools, this is the temperature where the thermocouple mini-plug is connected to the calibrator.

Rφ:

The resistance value of an RTD probe at 0 °C. Example PT100-385, Rφ = 100 Ω.

RTD:

Resistance Temperature Device, a temperature measurement sensor that has predictable changes in resistance with a change in temperature. The most common RTD is the platinum PT100-385.

Seebeck Effect:

Thermoelectric effect in which the voltage potential increases with temperature (thermocouples) in a junction of dissimilar metals.

Triple Point of Water:

This temperature reference point is the intrinsic standard at which water is liquid, ice and gas. This reference point defines 0.01 °C.