Design Of Zero Crossing Switching System Based On AC Contactor

Modern development of coal preparation plant is more and more tend to be large and mechanization, management of technical personnel and production department staff not only with their experience and energy to produce. To maximize the use of automation instrument to monitor production and management. The realization of the production process automation must depend on all kinds of instruments and devices to construct a set of control system, such as all kinds of electric and electronic components, motor and so on. The low pressure electric appliance is a basic part of a factory automation system, is the foundation and guarantee to the safe operation of the power system. Has a number, targeted a wide range of features, application of the most widely in the production and living. In the production of electricity transmission and distribution plays a regulation control, detection protection role. Some of the low-voltage electrical appliances, such as the knife switch, switch, circuit breaker, relay, contactor, etc with the switch of mechanical contact. But in use process will inevitably have many problems, such as in the current on and off, especially on off large current, mechanical contact can produce arc, the high temperature could switch contact burned, moreover can lead to switch electrical explosion and fire.In coal preparation plant dust accumulation phenomenon is very serious, such as the coal pit, the original coal, raw coal screening crushing workshop, etc. If the switch electrical appliances in the workplace prone to arc, arc encountered dust is major accidents may occur. So, in these produce maximum is necessary to avoid the generation of electric arc.In order to achieve accurate arc extinguishing function, we to design of ac contactor, STC89C52 MCUAs the core components, including hardware circuit design and software design. The hardware design mainly includes the power circuit design, the voltage and current zero point signal acquisition and processing circuit, the driving circuit design and so on. The software design includes the design of the main program, the relay driver design, the voltage and current zero point acquisition program design, etc.. In both ends of the mechanical contact switch voltage zero crossing switch is closed, current pass through zero TB open contacts, to realize the true meaning of arcless breaking, so as to achieve the arc.