Mjerenje temperature otporničkim osjetilima s negativnim temperaturnim koeficijentom

master's thesis

• Title (english): Temperature measurement using sensors with negative temperature coefficient
• Author: Marina Jozić
• Mentor: Damir Ilić (mentor)
• Committee member: Damir Ilić (predsjednik povjerenstva)
• Committee member: Ivan Leniček (član povjerenstva)
• Committee member: Mario Vražić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2015-07-08, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

U ovom radu opisan je princip rada kovinskih, PTC i NTC otporničkih osjetila temperature. Analizirane su i grafički prikazane njihove R(T) karakteristike, navedeni su materijali od kojih se izrađuju, te je opisana primjena pojedinih osjetila. U poglavlju 2.1. naglasak je na kovinskim osjetilima gdje je opisana i Pt-25 sonda koja je korištena kao referenca pri umjeravanju. U poglavlju 2.3. fokus je na osjetilima s negativnim temperaturnim koeficijentom, tu spadaju osjetila koja su umjerena u okviru ovog diplomskog rada. Opisana su dva načina na koja se mogu dobiti parametri aproksimacijske krivulje na temelju koje se iz izmjerenog otpora dobiva vrijednost temperature što je uspoređeno sa Steinhart-Hartovom formulom. Za određivanje nepoznatih parametara korištena je metoda najmanjih kvadrata. Glavnina rada je u poglavlju 3. Najprije je opisan set-up (mjerni postupak s mjernom opremom), nakon toga napravljen je proračun baziran na podacima iz poglavlja 2.1.2. i 2.3.4., te je na kraju napravljen prikaz rezultata i usporedba s rezultatima umjeravanja tih otpornika prijašnjih godina. Pokazano je da mjerna nesigurnost može biti na razini 10 mK ili čak i bolja za uži temperaturni raspon.

Abstract (english)

In this diploma work, the working principle of resistance temperature detectors and thermistors (NTCR and PTCR) is described. Their table data for resistance-versus-temperature dependence are given and analysed as well as the use of certain sensors.
In chapter 2.1. the emphasis is placed on the resistance thermometers, also called resistance temperature detectors. Afterwards, there is also a description of the Pt-25 probe, which was used as a reference during calibration.
The chapter 2.3. focuses on the sensors with a negative temperature coefficient, while also describing calibrated NTCRs and their characteristics.
Determination of two approximation curves is described: a three parameter one (AC1) and a two parameter one (AC2) which are compared with the three-parameter Steinhart-Hart equation by using table data of NTCRs and calculating unknown parameters by the least-square method. Temperature is therefore approximated using determined parameters and the difference from the reference temperature is calculated.
The main part of this diploma work is displayed in section 3. First there is an explanation of the set-up (measuring procedure with measuring equipment), after which a calculation based on data from chapter 2.1.2. and 2.3.4. follows. Finally, the results of calibration of these resistors from previous years are compared with the new results. It has been shown that the measurement uncertainty can be at the level of 10 mK or even better for narrower temperature range.

• Keywords: termistori; NTC; PTC; RTD; otpornička osjetila; umjeravanje; metoda najmanjih kvadrata
• Keywords (english): thermistor; NTCR; PTCR; RTD; resistance temperature sensor; calibration; least-square method
• Language: croatian
• URN:NBN: urn:nbn:hr:168:093850
• Study programme: Title: Electrical Engineering and Information Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije (magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2018-02-06 09:28:23