A Three-Wire Insulator-Shunting Model for High-Temperature Thermocouple Errors

An equivalent circuit and computer solution were formulated for describing the output of a metal-sheathed bifilar thermocouple degraded by insulator shunting at high temperatures. This steady-state equivalent circuit model can be used for prediction of errors in thermocouple calibrations, for examining the effects of changes in thermocouple configuration or materials properties, and for examining methods for interrogation or surveillance of the shunting thermocouples.