TABLE OF CONTENTS Most engineering design requires data for use in the analysis phase of the design process. This data must be obtained through measurement and these measurements must be obtained by means of instrumentation. The generic instrumentation system consists of the primary sensing device, that is the transducer, the lead wires and the secondary instrumentation.
A transducer is a device which changes one form of energy into another form. The final form of energy is usually an electric signal that is read and interpreted by the secondary instrumentation ie. read out device. There are many types of transducers such as thermocouples, strain gages, piezoelectric crystals, linear variable displacement transformers (LVDT) and a host of other types.
A thermocouple is a device which operates on the principle of basic material property variations caused by temperature differences. There are three so called thermoelectric effects caused by these temperature differences. Fortunately, the most significant one is the Seebeck effect which is the junction potential produced when two dissimilar are joined together. The emf that is produced is directly proportional to the temperature difference between the junction of the dissimilar metals and the junctions of the readout device or the reference temperature.
Q:
A simple thermocouple is used to measure the temperature of boiling water at standard conditions of the environment. Determine the emf output of thethermocouple in terms of the thermoelectric coefficient a, and the temperatures.
Figure 7-1
Answers
Q:
Since the electromotive force produced by the thermocouple is dependent directly...
