Static Temperature-measurement Errors Using NTC Sensors

2006 ◽  
Author(s):  
J. Engert ◽  
B. Fellmuth
Keyword(s):  
Temperature Measurement ◽  
Measurement Errors

scholarly journals Correlation Between Insulation Resistance and Temperature Measurement Error in Type K and Type N Mineral Insulated, Metal Sheathed Thermocouples

2022 ◽  
Vol 43 (3) ◽  
Author(s):  
Jonathan Pearce ◽  
Declan Tucker ◽  
Carmen García Izquierdo ◽  
Raul Caballero ◽  
Trevor Ford ◽  
...  
Keyword(s):  
Temperature Measurement ◽  
Measurement Errors ◽  
Insulation Resistance ◽  
Monitoring And Control ◽  
Type K ◽  
Reference Type ◽  
Process Monitoring And Control ◽  
Resistance Breakdown ◽  
And Control

AbstractMineral insulated, metal sheathed (MI) Type K and Type N thermocouples are widely used in industry for process monitoring and control. One factor that limits their accuracy is the dramatic decrease in the insulation resistance at temperatures above about 600 °C which results in temperature measurement errors due to electrical shunting. In this work the insulation resistance of a cohort of representative MI thermocouples was characterised at temperatures up to 1160 °C, with simultaneous measurements of the error in indicated temperature by in situ comparison with a reference Type R thermocouple. Intriguingly, there appears to be a systematic relationship between the insulation resistance and the error in the indicated temperature. At a given temperature, as the insulation resistance decreases, there is a corresponding increasingly negative error in the temperature measurement. Although the measurements have a relatively large uncertainty (up to about 1 °C in temperature error and up to about 10 % in insulation resistance measurement), the trend is apparent at all temperatures above 600 °C, which suggests that it is real. Furthermore, the correlation disappears at temperatures below about 600 °C, which is consistent with the well-established diminution of insulation resistance breakdown effects below that temperature. This raises the intriguing possibility of using the as-new MI thermocouple calibration as an indicator of insulation resistance breakdown: large deviations of the electromotive force (emf) in the negative direction could indicate a correspondingly low insulation resistance.

The Selection of Thermistors for the Temperature Measurement Gear

1970 ◽  
Vol 111 (5) ◽  
pp. 59-62
Author(s):  
J. Leskauskaite ◽  
A. Dumcius
Keyword(s):  
Temperature Measurement ◽  
Measurement Errors ◽  
Numerical Data ◽  
Optimum Selection ◽  
Selection Of

The parameters represented on manufacturer datasheet are usually insufficient for the optimum selection of thermistors. Some manufacturers give generalized numerical data of R(T) dependences. Using this data it is possible to select successfully the most suitable thermistor and equation for describing of T(R) dependence. It is shown that by selecting four points in the generalized characteristic it is possible to calculate the coefficients of the approximation equation. By the application of these coefficients in the calculations the temperature measurement errors can be decreased by an order. The results of calculations and experiment are given. Ill. 4, bibl. 8, tabl. 5 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.357

Transient Temperature Measurement Errors in Heated Slabs for Thermocouples Located at the Insulated Surface

1961 ◽  
Vol 83 (4) ◽  
pp. 505-506 ◽  
Author(s):  
D. R. Burnett
Keyword(s):  
Temperature Measurement ◽  
Measurement Errors ◽  
Wire Diameter ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
Slab Thickness ◽  
Cold Side ◽  
Thermocouple Wire

A method is developed for estimating the error in “cold side” transient temperature measurements of slabs heated at one surface which is due to conduction of heat away from the junction through a thermocouple wire. Results are presented for a range of slab thickness/wire diameter ratios.

Pyrometric Temperature Measurement in Concentrated Sunlight With Emissivity Determination

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Nathan B. Crane
Keyword(s):  
Temperature Measurement ◽  
Measurement Errors ◽  
Low Cost ◽  
Random Noise ◽  
Temperature Data ◽  
Temperature Measurements ◽  
Solar Furnace ◽  
Surface Emissivity ◽  
Specialized Equipment ◽  
The Difference

Pyrometers are commonly used for high temperature measurement, but their accuracy is often limited by uncertainty in the surface emissivity. Radiation heating introduces additional errors due to the extra light reflected off the measured surface. While many types of specialized equipment have been developed for these measurements, this work presents a method for measuring high temperatures using single color pyrometers when the surface emissivity is unknown. It is particularly useful for correcting errors due to reflected light in solar heating applications. The method requires two pyrometers and is most helpful for improving measurement accuracy of low cost commercial instruments. The temperature measurements of two pyrometers operating at different wavelengths are analyzed across a range of sample temperatures to find the surface emissivity values at each wavelength that minimize the difference in temperature measurements between pyrometers. These are taken as the surface emissivity values, and the initial temperature measurements are corrected using the calculated emissivity values to obtain improved estimates of the surface temperature. When applied to temperature data from a solar furnace, the method significantly decreased the difference in the temperature measurements of two single color pyrometers. Simulated temperature data with both random noise and systematic errors are used to demonstrate that the method successfully converges to surface emissivity values and reduces temperature measurement errors even when subjected to significant errors in the model inputs. This method provides a potential low cost solution for pyrometric temperature measurement of solar-heated objects. It is also useful for temperature measurement of objects with unknown emissivity.

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