Process variable transmitter with thermocouple polarity detection

摘要

A process variable transmitter for measuring a temperature of an industrial process, includes a first electrical connector configured to couple to a first wire of a thermocouple, the first electrical connector includes a first electrode and a second electrode. The first and second electrodes are configured to electrically couple to the first wire of the thermocouple. A second electrical connector is configured to couple to a second wire of the thermocouple, the second electrical connector includes a third electrode and a fourth electrode. The third and fourth electrodes are configured to electrically couple to the second wire of the thermocouple. The second wire is of a different material than the first wire. Measurement circuitry is coupled to the first and second electrical connectors configured to provide an output related to a temperature of the thermocouple. The measurement circuitry is further configured to identify polarity of thermocouple based upon at least one measurement taken between at least two of the first, second, third and fourth electrodes.

主权项

1. A process variable transmitter for measuring a temperature of an industrial process, comprising:
a first electrical connector configured to couple to a first wire of a thermocouple, the first electrical connector comprising a first electrode and a second electrode, the first and second electrodes configured to electrically couple to the first wire of the thermocouple; a second electrical connector configured to couple to a second wire of the thermocouple, the second electrical connector comprising a third electrode and a fourth electrode, the third and fourth electrodes configured to electrically couple to the second wire of the thermocouple, the second wire of a different material than the first wire; and measurement circuitry coupled to the first and second connectors configured to provide an output related to a temperature of the thermocouple, the measurement circuitry further configured to identify polarity of thermocouple based upon at least one voltage measurement taken between at least one of the first and second electrodes or the third and fourth electrodes and as a function of the first and second wires of the thermocouple being of different materials, wherein the first and second electrodes comprise different materials and the at least one voltage measurement has a value which is different when the thermocouple is connected with a correct polarity than when the thermocouple is connected with a reversed polarity.