A self-validating thermocouple

Traditionally the sensor has been the system component neglected by control engineers, yet it has long been recognized that accurate and reliable sensor readings are vital for good controller performance. Self-validating sensors can improve reliability through self-diagnosis and by the provision of on-line metrics (measurement accuracy and its trustworthiness). One benefit of validation is the potential to sustain satisfactory loop performance even in the presence of sensor faults. This paper describes a self-validating thermocouple that can discover several types of internal fault, including the practically important aspect of loss-of-contact with the process environment, and shows how the associated uncertainties can be calculated. The operation of the device is demonstrated through a series of experiments.