Development And Application Of The Signal Isolation Safety Barrier In The Condition Monitoring Of Armoured Face Conveyor In Coal Mine

The project in this thesis is one important part of the project " condition monitoring and fault diagnosing system used in the conveying equipments installed in the fully-mechanized coal face ", which is the sub-topic of the project " a complete range of the equipments and key technology in the fully-mechanized coal face with capacity of annual production of10million tons ", sponsored by the National Key Technology R&D Program of China during the Eleventh Five-year Plan Period. The subject is proposed to solve the problem of signal transmission and intrinsically safe isolation in the condition monitoring of armoured face conveyor in coal mine. According to the special environment of the application site in the condition monitoring of armoured face conveyor in coal mine, the principle of magnetic isolation and the target of solving the problem of signal transmission between the sensor and the measuring instrument, two kinds of signal isolation safety barriers were developed for the system hazardous area which were used to isolate and transfer temperature, pressure, liquid level and flow signals based on simulation, circuit debugging, intrinsically safe explosion-proof and electronic product environmental tests in this thesis. The test results show that, the development of signal isolation barrier can isolate and transfer the danger signals of intrinsically safe side and supply intrinsically safe power, the main contents are listed as follows:After consulting of foreign and domestic references, function, classification and technical index of safety barrier were summarized and analyzed on the basis of signal transfer function demand in the condition monitoring of armoured face conveyor in coal mine. And according to the monitoring signal types, the overall schemes of signal isolation safety barriers in the thesis were proposed. Signal isolation safety barriers in the thesis include isolated safety barrier for measuring thermal resistance and isolated safety barrier for measuring4-20mA current signal, isolated safety barrier for measuring thermal resistance was used to acquisite and isolate temperature signal in the dangerous side, and another provided the intrinsically safe power for the sensors in the dangerous side and at the same isolated and transferred the pressure, liquid level and flow signals in the dangerous side.Considering the signal transfer safety requirement in the condition monitoring of armoured face conveyor in coal mine, the circuits of signal isolation safety barriers were designed, the design principle of intrinsically safe protection circuits were described, the isolation transformer parameters calculation were completed. The two kinds of isolation safety barriers through the power, signal processing, intrinsically safe protective isolation aspects to realize the monitoring signal collection, isolation, transportation and intrinsically safe energy control, the hardware circuits were designed simple and reliable, meet the design expectation of the safety barriers.The power conversion circuit, thermal resistance measuring circuit and signal demodulation circuit were simulated through Saber and Multisim two softwares, simulation models were constructed, the simulation calculation was completed. The simulation results showed that, the circuits were designed reasonably, the simulation models were true, the circuits were improved and optimizated, the simulation effect was achieved.The isolation transformers with independent research and development were used in the isolated safety barrier for measuring thermal resistance and the isolated barrier for measuring4-20mA current signals, and the development of signal isolation barriers could isolate and transfer the danger signals of intrinsically safe side and supply intrinsically safe power. Debugging results show that:the circuits were designed reasonable, the output was accurate and stable, and the expected design goals were achieved. It meet the actual needs of the condition monitoring system of armoured face conveyor in coal mine, and had high economic and practical value, and provided an important guarantee for the safe operation of intrinsically safe side.Considering the special environment of signal isolation safety barriers application, the intrinsically safe explosion-proof and environment tests were needed. The spark ignition tests of signal isolation safety barriers were passed successfully, the hazardous energy in the intrinsically safe side was controlled, the voltage withstand test of the isolation transformer with independent research and development was tested to be qualified, the expected technical indicators and the explosion-proof standards for isolation safety barriers were achieved. In the environmental tests of electronic products, signal isolation safety barriers were normal in a variety of harsh environment, the output was stable and accurate, the expected design goals were meet, safety barriers could be applied to the mine and other special environment.