Next Generation Sensor for the Turbin Engine Industry

Thermocouples are extremely important to the operation of turbine engines. While they are
the most rugged and reliable temperature sensors available, it is well known that
thermocouples experience de-calibration or "drift" while in service. There is no reliable
way to tell when thermocouple drift begins to occur or to determine its magnitude or
direction. De-calibration is not only a problem for turbine engine operators. The
uncertainties resulting from thermocouple "drift" cost industry millions of dollars each
year in off-quality product, less than optimum yields, underutilized capacity, unnecessary
emergency shutdowns, reduced equipment life and safety and emissions problems. Two
major improvements to thermocouple technology have been developed. A new Metal
Sheathed Mineral Insulated (MIMS) cable has been developed that is superior to that
commonly used to make the thermocouples used in turbine engines. Tests show that
thermocouples made with this new cable have greater signal stability and can give 3 - 4
times the life of standard thermocouples. Building on this technology, Dynamically Self-
Validating Sensors have been invented that eliminate unreliable readings altogether and
warn in advance of the onset of drift. This paper will focus on the development of the new
MIMS cable and also introduce the concept of Self-Validation. An example of the benefits
of applying these new technologies to a turbine engine powered electrical generation unit
will be discussed.