A temperature calibrator is a set of instruments combined to perform calibration. It consists of a stable temperature source capable of reaching the desired range of temperatures, a probe traceable to SI units, and an accurate way to read the temperature output from the standard and the device under test to compare the readings.
It is normal practice to use a reference PRT in conjunction with a bath or well for calibrating temperature devices such as PRTs and thermocouples. This PRT will generally have its own separate readout, although some portable wells and baths that are designed for field or plant use have a reference PRT readout built-in, in order to minimize the amount of equipment needing to be carried by the technician.
Sometimes temperature calibration equipment is automated to reduce time and errors while operating in the calibration labs. This also allows personnel to complete other tasks while calibration is occurring.