Research On Electrical Life Testing System And Key Technology Of Contactor

AC contactor is a kind of low-voltage electrical apparatus, which is used to switch on and off the power load and control circuit. It has widely used in the Automation controlling and electrical load controlling. Electrical life is the most important factor affecting the life of the contactor. Electrical life testing is the direct and effective way to predict the state of the AC contactor.In this paper, the present situation and development trend of the electric life testing system are summarized and the researching status at home and abroad is described.According to GB and IEC(International Electrical Commission) standards, a new contactor electric life testing equipment is designed in this paper. The basic information of the AC contactor, the experiment conditions, the designing of the test circuit and the selection of the test equipment are described in detail. Then the working principle and designing scheme of the electric life testing equipment are analyzed. At the same time, the rationality of the experimental equipment is verified.The control system of electrical life test equipment is composed of touch screen and PLC. The overall designing of the controlling system for the electric life testing equipment is introduced in this paper. The experiment equipment uses Wincc flexible configuration software to control the software system and the Step-7 configuration software to control the hardware system. EM235 analog module is used to convert analog and digital, voltage and current sensor are used to detect the voltage and current in the equipment. This system can realize the function of the experimental process controlling and the system voltage and current monitoring and the test data recording and alarming and so on. Through this equipment, the automatic control of the experiment processing of the electrical life of the contactor can be realized.There is a problem in the testing equipment, the life of the accompany contactor is far lower than the tested contactor, the accompany contactor needs to be replaced during the experiment which making the testing process inconvenience. So the paper puts forward the viewpoint that a new kind of magnetic controlled transformer is used in the testing equipment. On the basis of the structure of the transformer, the using of the principle of saturated reactor can realize the change of the output voltage with the control current andavoid the using of the accompany contactor. Magnetic saturation transformer is a kind of special structure transformer, which is based on the saturated reactor. Increasing on both sides of the core with magnetic circuit control core to form a four-column structure of new transformers. According to the principle of magnetic saturation reactor with the change of control current, the output voltage can be changed along with the corresponding linear relationship.