Study On Computer Measure And Control Technology Of AC Contactor Electric Life Test

As the basis apparatus components, which are use to switch on and switch off main circuit or big capacity control circuit, AC contactors are widely used in control of electromotor and other power load. The electric life of the AC contactors, which is generally 5%~20% of the mechanical life, is the critical factor of contactors life. The contactors test is the important way of testing the performance and quality of AC contactors.According to requirement of electric life test, the AC contactors electric life test equipment, which is controlled by industrial PC, is studied. Three part of the equipment: power supply, simulative load and computer test and control is introduced respectively. The conditions of voltage between contactors and current in main circuit under different using types are analyzed in detail, then designed the control sequences with working mode AC1-AC4. Using Advantech's PCL818HG DAS card, the equipment examines the voltage and current in the main circuit in real-time. Under operation system of DOS and Windows, control software is developed respectively. The wave of voltage and current as the AC contactors switch-on and switch-off is displayed dynamically, which make the equipment not only used as general electric life test instrument, but can apply test date for contactor study. The equipment has the function of self-check and precision checkout, which improved the automation level of test.Besides, digital signal processing technology in AC contactors electric life test is studied in this paper. Under the principles of digital signal processing, using FFT, the calculate process of power supply frequency and power factor is discussed. In order to satisfy the real-time measurement, we studied the fast arithmetic of virtual value of voltage and current, power factor.