| The accuracy of temperature measurement and monitoring has significant importance in ensuring the safety of operation for machinery, ships, and industrial equipment. Whether the temperature is accurate or not is mainly depends on the temperature sensor and the electronic temperature instruments. Electronic temperature instruments are kinds of apparatus which measure, display and control the temperature according to the output signal (i.e. voltage, current) of temperature sensor, and common temperature sensor contains thermal couple and thermal resistor. Due to the impact of working environment and incorrect operation, electronic temperature instruments may result in certain kind of inaccuracy or malfunction. The main task of this project is to design a portable temperature calibrator with high precision and lower price which can meet the requirements of materials'thermal processing. It can also simulate the output of temperature sensors, such as thermal couple and thermal resistance.This paper analyzed the common temperature calibrators on the market, describing the advantages and disadvantages of each. Combine with the requirement of electronic temperature instruments'needs for temperature calibrator in materials'thermal processing, this paper put forward the parameter of this instrument.After comprehensive consideration of both accuracy requirements and cost control, we set the design scheme for this program. The portable temperature calibrator mainly contains LED displayer, matrix keyboard, DA converter, temperature sensor for environmental temperature compensation, C8051F serials MCU.The calibrator can simulate the output of thermal couple and thermal resistance, it's convenient to operate. When power on, the LED displays"----", indicating the system is on power and it's available for the next to come operation. Set the target temperature through matrix keys, then press"start"button to start the conversion. Only if the signal on the output interface is within the allowed error range the LED will display the temperature selected, then lead the output into the electronic temperature instrument to be calibrated, this is the end of one calibration process. Waiting LED when it displays"----"again, and it's time for the next calibration.This paper gives detailed explanation for chip selection, hardware design, PCB layout, software design, and execute testing and analysis for the output, it has been illustrated that the calibrator can meet the requirements of calibrating electronic temperature instruments in industrial application. This calibrator is a low-cost, portable temperature calibrator with high accuracy and stable performance. |
