Online calibration of a temperature measurement point

• US 9,250,141 B2
• Filed: 03/09/2013
• Issued: 02/02/2016
• Est. Priority Date: 06/11/2009
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Engelstad, Loren Michael, Bauschke, Dirk Willy, Rud, Jason Harold
• Primary Examiner(s): Kaplan Verbitsky, Gail
• Application Number:
  US13/791,999
• Publication Number:
  US 20130182741A1
• Time in Patent Office: 1,060 Days
• Field of Search: 374/1, 374/163, 374/170, 374/179, 374/183, 374/185, 374/208, 374171-172, 702/99, 340/870.17, 327/512, 327/513
• US Class Current: 1/1
• CPC Class Codes: G01K 1/14 Supports; Fastening devices; Arrangements for mounting thermometers in particular locations
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 15/005 Calibration

Abstract

A method for calibrating a transmitter with measurement circuitry electrically connected to first and second input terminals includes connecting a primary temperature sensor to the first input terminal and connecting a calibrated reference device to the second input terminal. The measurement circuitry is calibrated with respect to the first input terminal according to signals received from the second input terminal while measuring temperature according to signals received from the first input terminal.

Claims

1. A method for calibrating a transmitter with measurement circuitry electrically connected to first and second input terminals, the method comprising:

connecting a primary temperature sensor to the first input terminal;

measuring temperature with the primary temperature sensor prior to connecting a calibrated reference device;

connecting the calibrated reference device that is external to the transmitter to the second input terminal, wherein the calibrated reference device is a reference calibration tool that generates a measurable electrical parameter with a predetermined value;

measuring temperature with the primary temperature sensor while the calibrated reference device is connected to the second input terminal;

calibrating accuracy of the measurement circuitry with respect to the first input terminal for transmitter drift according to signals received from the second input terminal while concurrently measuring temperature according to signals received from the first input terminal;

disconnecting the calibrated reference device from the second input terminal; and

measuring temperature with the primary temperature sensor after disconnecting the calibrated reference device,

wherein calibration takes place without interrupting measurement of temperature based on signals from the primary temperature sensor, and temperature is measured with the primary temperature sensor before, during, and after the calibrating step, without interruption.

2. The method of claim 1, wherein the measurable electrical parameter is resistance or voltage.

3. The method of claim 2, wherein calibrating comprises:

measuring the measurable electrical parameter and generating a measured value with the measurement circuitry;

transmitting an actual predetermined value to the measurement circuitry;

comparing the measured value to the actual predetermined value and generating a corresponding calibration adjustment; and

calibrating the measurement circuitry based upon the corresponding calibration adjustment.

4. The method of claim 1, and comprising:

initializing calibration of the measurement circuitry with a first user input; and

confirming calibration adjustment one or more trim values of the measurement circuitry with a second user input.

5. The method of claim 1, wherein the primary temperature sensor has a temperature detector inserted within a bore of a thermowell.