US 6,045,260 A · Switch for selectively coupling a sensor or calibration element to a terminal block

Abstract

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.

Claims3

Dependent claims

A system comprising a junction box coupled to a terminal block, a sensor, and a reference element, the junction box, comprising:

first connections configured to couple to four terminals of the terminal block of a transmitter in a process control system;
second connections configured to couple to four terminals of the sensor;
a calibration input configured to couple to four terminals of reference element;
the system further comprising a switch movable between a first position in which the first connections are coupled to the second connections through four separate parallel connections and a second position in which the first connections are coupled to the calibration input through four separate parallel connections.

1 more element

Dependencies are inferred from the claim text.

Facts

Application

09/177,414Filed 23 Oct 1998 · division

Priority

27 Sep 1994

Granted

4 Apr 2000

Term ends

Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01K 7/20
The element being a linear resistance, e.g. platinum resistance thermometer: in a specially-adapted circuit, e.g. bridge circuit
G01K 7/13
Arrangements with respect to the cold junction, e.g. preventing influence of temperature of surrounding air: circuits for cold-junction compensation
G01K 15/00
Testing or calibrating of thermometers
G01K
Measuring temperature

Switch for selectively coupling a sensor or calibration element to a terminal block

Life of this patent

Switch for selectively coupling a sensor or calibration element to a terminal block

Life of this patent

Abstract

Claims3