| Being directed at the problem protector for monitor longitudinal rip of converyor belt had that low reliability, poor anti-interference ability, and inconvenient operation, then coulped with the status that large dust, special circumstances of invisibility and low degree of automation in coal mine, this thesis designed the new non-contact system for monitor longitudinal rip of belt conveyor which has infrared photoelectric sensor for monitoring, high anti-interference ability, high automation and convenient operation.Firstly, in order to promote the reliability and the anti-interference ability of sensor, and preclude the bad condition caused by the malfunction of sensor, this paper taken account the monitoring sensor, detect the object, reference standards and other factors.on the one hand,this thesis analyzes the infrared photoelectric sensor and its characteristics, upgrade the present sensor with infrared pulse modulation, and improve the penetration and anti-interference ability of ambient light of infrared sensors. On the other hand, using optical detection principle, achieve real-time fault diagnosis function of sensor, which could diagnose the situation of sensor that does not work which is caused by optical axis changes, dust, and oil of lens or other factors and then guarantee the safe operation for the conveyor belt.Secondly, in the course of design, after study the design theory of control system hardware of PLC, coupled with the design requirements of system for monitor longitudinal tear of conveyor belt, identified the overall structure which centered by siemens S7-200 PLC, this thesis designs the system control device and external alarm device, which complement the system hardware and developed system software and configuration the touch screen based on the process requirement. Besides, in order to satisfy the application requirements of explosion-proof, paper adopts the explosion proof design style and intrinsically safe explosion proof design to the hardware. In order to ensure the system security and reliability of signal transmission, this thesis adopts the reliability design approach form the perspectives of hardware and software respectively. From the design of hardware, the power supply isolation, signal input and output isolation, and system grounding are adopted; from the design of software,digital filter statement, analog filtering and fault detection procedure statement are designed.At last, the system prototype is applied to mine conveyor belt monitoring longitudinal tear after tested success on the ground. It is shown that this non-contact protector for monitor longitudinal tear of conveyor belt can monitor the accidence of tape on the condition of normal operation of conveyor, and make machine stop and alarm promptly. It is significant to promote the development of our country's belt longitudinal tear monitoring technology.
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