Phase Selection Excition Of Contactor And Its Detection Technology

Ac contactor is one of the automatic electrical components to make ac circuits frequently switched-on or switched-off in a long-distance. And it is widely applied in all kinds of low voltage distribution system and automatic control system, and it is a necessary component in electrical automatic device. The start-up process of ac contactor is closely related to the brake phase angle. Since the contactor control voltage signal of the ac contactor is ac alternating, the dynamic characteristic is different as closing phase angle is different, when contactor is closing in a different angle. Besides, they are all different, such as the bounce time of contactor, variation rule of the armature velocity, as well as the collision energy. The main harm of contactor bounce is making arcing chamber contactor wear more quickly, so it shortens the chamber electric life. Therefore, the bounce of the contact is important parameters of the contactor properties when it is switched-on.The paper uses one-chip computer C8051f120 MCU based on the analysis of phase selection excitation of contactor; and then it makes ac contactor phase-selection excitation detection system based on single-chip microcomputer system. The system can set the excitation phase angle in the man-machine interface and control excitation by computer operation; it also can show test results, making the detection of the contactor phase-selection excitation and contactor bounce intelligent and visual. The system contains hardware and software. Hardware mainly includes the detection circuit based on the one-chip computer C8051f120 MCU, the control circuit and the USB communication circuit between the single-chip microcomputer and computer. The lower level computer programs by C language. It designs the program of the voltage parameters, phase-selection excitation, data storage and USB serial communication etc, besides it designs the PC man-machine interface by VC ++ 6.0 programming.