Design And Realization Of Temperature Rise Test System Based On LabVIEW

Low-voltage electrical equipments play a very important role in various industries of the national production, whose quality affects not only the security of the production process, but also the safety of our lives. In many quality tests for low-voltage electrical equipments, the temperature rise test is used to assess whether the heat of each part exceeds the allowable value under the specified condition. Therefore, obtaining data accurately in the temperature rise test is being of great significance for analyzing whether the low-voltage electrical equipments could work safely.In the context of "10KA temperature test equipments" project, this paper has made full use of the advantages of virtual instrument technology in the field of measurement. Besides, combined with field measuring equipments, this paper has designed a data acquisition system which based on LabVIEW for the temperature rise test of low-voltage electrical equipments.Firstly, according to the characteristics and requirements of low-voltage electrical temperature rise test, the hardware and software are designed for the data acquisition system, whose main contexts are data acquisition and analysis of main parameters in the temperature rise test,such as current, voltage and temperature. On one hand, data acquisition of voltage and current uses Siemens S7-1200 PLC as the data acquisition and processing unit, by applying OPC communication technology to exchange data with the host computer through industrial Ethernet. On the other hand, a 16 AI channels temperature acquisition card has been designed for the collection of temperature. The temperature acquisition card chooses STM32 microprocessor as the master chip to coordinate the work among processing modules and it integrates thermocouple amplifier MAX6675 chip to amplify temperature signals collected by K-type thermocouple and do the A/D conversion. STM32 microprocessor and MAX6675 exchange data through the configuration of SPI interface.Finally, it sends the temperature value to the host computer by using the Modbus RTU protocol via the serial interface.Secondly, the data acquisition system can be monitored based on the LabVIEW platform. It can display the voltage, current and temperature in real time through the VISA port and OPC service configuration. There are two display modes, one of which uses values and another uses curve. Also, it has information management functions of setting test parameters, temperature limit alarm, automatically saving data and so on.Finally, through the actual test of the system, it turns out that each module of the data acquisition system which based on LabVIEW works properly. The data acquisition system can complete the job of the data collection and recording in the temperature rise test. The design goal has been achieved.