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Szybka korekcja statycznych charakterystyk termometrycznych termistorów

Gołębiowski J., Gozdur R., Majocha A.

Pomiary Automatyka Kontrola

2012

R. 58, nr 1

19-22

W artykule przedstawiono metodę szybkiej korekcji statycznych charakterystyk termometrycznych termistorów. Zastosowano komputerowy system pomiarowy z wzorcowym czujnikiem platynowym oraz elementem wykonawczym w postaci pompy ciepła Peltiera. Zaprezentowano wyniki pomiarów. Przestawiono metodę wyznaczania zmodyfikowanych parametrów charakterystyki termometrycznej na podstawie przeprowadzonych pomiarów.

The paper presents a method for fast correction of static characteristics of NTC thermistors and a measurement-control system with dedicated software. The measurement system uses a high performance current source and ADC card with 16-bit converter and a USB interface. The control unit uses a three-stage Peltier heat pump that enables fast and simple stabilization of the temperature in the range (20 ÷ 85) °C. Using a software PID controller and a standard Pt100 temperature sensor the stability achieved was at the level of š 0.02°C over the full range. Corrections were carried out by classifying sensors to one of three categories (I, II, III) and then a specific set of coefficients was assigned for the static characteristics. The paper presents the detailed algorithm for the procedure including the method for determining the adjusted static characteristic coefficients. The coefficients were determined by the optimal value search method minimising along orthogonal directions. Approximately 20% of the test sample that contained 35 pcs sensors did not require correction. The accuracy of other sensors was improved three times at least by the correction applied.

Electrical properties comparison of NTC thermistors prepared from nanopowders and in mixed oxide process

Hosseini S. M., Ghanbari Shohany B., Azad N., Kompany A.

Materials Science Poland

2011

Vol. 29, No. 4

253--259

We have synthesized and studied the effect of cobalt doping on the electrical properties of NTC thermistors with the composition of NiCoxMn2-xO4 (x = 0.0, 0.4, 0.8, 1.2, 1.6). The electrical properties of NTC thermistors prepared from nanopowders by gel auto-combustion and mixed oxides processes have been compared. The measurement results indicate that the fluctuations of B value in the samples made from nanopowders are smaller than that in the samples prepared using mixed oxides method. The electrical properties of these ceramics depend strongly on their grain size. The sintering time and temperature were chosen the same for the samples made from the powders prepared by the two methods. It was found that the samples made from nanopowders have smaller grain sizes.