Patent ID: 7744276

Claim:
A method of determining thermocouple integrity with a measurement arrangement comprising a thermocouple, a controller or processor, a digital multiplexer and a test circuit; the method comprising: (a) the controller or processor taking a temperature reading from the thermocouple using a first circuit, (b) the controller or processor switching on or off the digital multiplexer, (c) the controller or processor receiving a signal utilizing the first circuit that is indicative of the temperature reading from the thermocouple, (d) the controller or processor activating the test circuit upon receipt of the signal in order to determine validity of the signal, (e) the test circuit, upon being activated by the controller or processor, sending an electric current to the thermocouple via a second circuit that is switched on and off to provide a test reading, (f) interrogating the test reading to check for the thermocouple being a closed or an open circuit to determine thermocouple integrity and the validity of the signal, and (g) accepting or rejecting respectively the temperature reading taken by the controller or processor by: predicting a result of the electric current passed along rails of the second circuit through the thermocouple and electrical resistances; interrogating the test reading; and if the result of the electric current is correctly predicted, the temperature reading taken by the controller or processor is accepted.