Experimental Study On Electrical Performance For Contact Materials Used In AC Contactor

The contactor is a kind of switching devices which is used to control heavy loads. In terms of industrial production, daily life, transportation and power supply, the contactors are widely used. It has become one of essential electrical device in daily life. Due to the wild range and harmful consequences while the contactors are damaged, High reliability and long electric life are required. As the electrical contacts are the weakest part of the contactor. The research on electrical performances within the electrical contacts is the key approach to improve the AC contactors’ reliability and electric life.First, a test equipment is designed which enables of measuring the contact’s dynamic force, contact voltage, contact current, contact displacement and coil current. While also being able to adjust the contact gap, replace the contact material and alter the load type for the contactor. The PC interface is also designed to realize the experimental parameters setting, test data/waveform display and data storageSecondly, the movement process of contacts are analyzed. A typical waveform recording by the test equipment is used to calculating the electrical parameters, including closing time, impact force, static force, arcing time, arcing energy and contact speed. According to the contact time – displacement/speed curve, a mathematical model of speed- displacement is established. Taking into account the amount of arcing parameters, using a statistical method to establish the arcing time and the arcing energy physics models and discusses the arc energy dispersion.In addition, the relationship between the electrical performance and the factors, including contacts gap, contact material and load type is studied via the equipment. The arcing time and arcing energy are focused in the study. The regulation between the contact gap and contact force, closing speed are also discussed. Study on the electrical performance parameters influenced by factors will help to optimize the contacts.Finally, the contacts after experiments are observed with the electron microscope, optical microscopy and X-ray spectroscopy to analyze its electrical erosion degradation mechanisms. The causes and characteristics of contacts’ physical degradation are elaborated. The state of contacts’ morphologies effected by the arcing energies is also discussed. Electrical contacts’ morphologies with different materials are studied in conjunction with material properties.This study will provide a test platform for measuring the electrical performance of contacts within AC contactor. And also will provide guidance and suggestions for the optimization and selection of contacts according to the test results...