Measurement of multi-channel cold junction temperature
AssigneeRockwell Automation Technologies, Inc.
InventorSteven Streicher
Life of this patent
Estimating the term…
Abstract
The cold junction temperature of the channels on a multi-channel terminal block are accurately determined for each terminal pair without affixing a thermistor to each terminal. One embodiment provides accurate cold junction measurement of a six channel device (12 terminals) by mounting or directly affixing only three sensors (e.g., thermistors). The present technique decreases cost by reducing the number of sensors to less than the number of channels or terminals, while providing for accurate cold junction measurement at each channel.
Claims27
A method of using thermocouples, comprising:
- disposing a temperature sensor at three or more respective terminals along a terminal strip having a plurality of terminals adapted to receive thermocouple signals;
- measuring temperatures at the three or more terminals;
- calculating temperatures of remaining terminals based on measured temperature values of the three or more terminals having the disposed temperature sensors;
- and
- calculating a cold junction temperature of the terminal strip of at least one thermocouple channel based on measured or calculated values of the terminals, or a combination thereof.
A method of measuring cold junction temperature in a multi-channel configuration, comprising:
- disposing temperature sensors at three respective terminals on a on a row of a multi-channel input device;
- measuring a temperature at the three terminals;
- interpolating or extrapolating, or a combination thereof, the temperature at the three terminals to give a temperature of remaining terminals on the row of the multi-channel input device;
- and
- combining terminal temperatures to determine the cold junction temperature of the respective channels.
An apparatus for measuring cold junction temperature, comprising:
- means for measuring temperatures at three or more terminals along a terminal strip having a plurality of terminals adapted to receive thermocouple wires;
- means for calculating the temperature of remaining terminals based on measured temperature values of the three or more terminals;
- and
- means for calculating a cold junction temperature of the terminal strip of at least one thermocouple channel based on measured or calculated values of the terminals, or a combination thereof.
A computer program, provided on one or more tangible media, for measuring cold junction temperature of a thermocouple, comprising:
- a routine for measuring temperatures of the three or more terminals along a row of a multi-channel cold junction block comprising a plurality of terminals;
- a routine for calculating temperatures of other terminals of the plurality of terminals based on measured temperature values of the three or more terminals;
- and
- a routine for calculating cold junction temperatures of channels on the row based on temperature values of the plurality of terminals.
An instrumented multi-channel input/output terminal assembly comprising:
- a multi-channel terminal strip for receiving inputs from a plurality of thermocouples;
- and
- at least three temperature sensors disposed at respective postions along the terminal strip, the temperature sensors being configured to detect a temperature at a respective postion along the terminal strip and to provide a signal representative of the temperature to a processing circuit.
Dependencies are inferred from the claim text.