Design Of Surface Temperature Tester For PTCR

As a thermistor whose resistance rises steeply with temperature,PTCR main performance in industrial applications is resistance temperature characteristics,current time characteristics,and voltage current characteristics.This subject designs a set of PTCR surface temperature tester based on the above three characteristics.In order to design a set of convenient and effective PTCR surface temperature automatic tester,this subject is designed from two parts about system software control and hardware circuit.Our software control part mainly includes two modules,the upper computer program and the lower computer program.The upper computer program is based on Qt5,which mainly includes system initialization,serial communication,data processing and curve display functions.The lower computer program of the single-chip computer is developed with keil5,it mainly realized the functions of temperature acquisition and data filtering,test channel selection,overcurrent protection threshold setting or reset.The hardware part mainly includes modules such as overcurrent protection,single-chip core control,relay drive,temperature acquisition and data conversion.By adopting the design idea of combining software and hardware,we split the entire system into several modules and implement them step by step,it also improves the development efficiency of the system.Before starting the test of the whole system,the communication function between the upper and lower computers should be established at first,and system initialization and self-checking was carried out then.After that,the upper computer will send information such as the surface temperature test instruction,program-controlled power supply pressure instruction and each lower computer will respond after receiving the matching command and parsing it.Make the programmable power supply output a stable voltage signal,single-chip microcomputer control pressure channel,over-current protection,temperature detection and other modules began to work.Temperature detection module is divided into PT100 platinum resistance contact temperature measurement and Mlx90614 non-contact temperature measurement two parts.Through the analysis and comparison of the advantages and disadvantages of the two temperature measurement methods,it can be seen that infrared temperature measurement is more inclined in low temperature environments.In high temperature environment,platinum resistance temperature measurement is preferred.At the same time,using the relationship curve of surface temperature and time,combined with the rise time and fall time parameters,the aging characteristics of PTCR can be more fully analyzed,and providing a powerful test method and tool for PTCR reliability test.