Rosemount Inc.

Bradley N Schwartz

William R Kirkpatrick

Donald W Selg

Stanley Kugler

A transmitter in a process control loop measures temperature. A calibrator includes a known calibration element which is connected to the transmitter. Software in the transmitter compares a measured value of the calibration element with the actual value of the calibration element and responsively calibrates the transmitter. The calibrator includes a temperature calibration sensor for coupling to a terminal block of the transmitter. The temperature calibration sensor provides an actual temperature input to the transmitter. The transmitter measures actual temperature of the terminal block and compares actual temperature with a temperature measured by an internal terminal block temperature sensor, and responsively calibrates the internal temperature sensor.

Switch for selectively coupling a sensor or calibration element to a

Calibration of process control temperature transmitter

A temperature transmitter connects to a first conduit containing leads from a temperature sensor and also to second conduit which conveys the output leads of the transmitter to a remote location. A wall in the transmitter divides the transmitter into first and second compartments sealed from one another. The first compartment receives the leads from the temperature sensor and contains the electric circuit for converting the signal of the temperature sensor to an output signal representative of temperature. A feedthrough passing through the wall connects the output signal to the output leads in the second compartment. The arrangement blocks the flow of potentially hazardous fluid from the first conduit through the second conduit to a remote location such as a control room. The transmitter thus provides an integral seal between the conduits and use of an external conduit seal in the second conduit can be avoided.

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Lakeville, MN, United States of America

Bradley N Schwartz