Enhancing thermocouple temperature measurement accuracy with local RTDs to compensate terminal temperature difference
US8996327B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 2012 |
| Grant date | Mar 31, 2015 |
| Priority date | — |
| Expiry date | Aug 17, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K7/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An I/O circuit for measuring temperatures uses multiple cold-junction compensation sensors permanently affixed near the terminals of the terminal block in order to compensate significant temperature variation across the terminals of the I/O module (up to 3° C.) that can substantially affect the accuracy of thermocouple measurements. The use of these multiple sensors is enabled by a compensation system that corrects for the distance between the built-in sensors and the terminals, a multiplexer that accommodates the additional signal burden produced by the sensors, and a compensation system that allows low-cost sensors to be used and calibrated to as little as a single high accuracy sensor. In one embodiment, a third temperature sensor with relatively higher accuracy is used to compensate for lower accuracy of permanently affixed sensors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.