Research And Development Of Gas Distribution System Based On Expert PID For Flameproof Test

Explosion-proof electrical equipment refers to electrical equipment that is used in explosion hazardous sites and is structurally designed to prevent sparks,arcs or dangerous temperatures from becoming a source of ignition for explosive mixtures.It is widely used in coal mines,hazardous chemicals,and blasting dust sites.Among explosion-proof electrical equipment,the flameproof electrical equipment has the widest application range,and its explosion-proof performance will have an direct influence on the safety of the entire using site.In order to verify the explosion-proof performance of flameproof electrical equipment accurately and efficiently,it is vital important to carry out the research on gas distribution systems of explosion-proof test.In view of the problem of the low stability of gas distribution of the ‘Tests of the ability of the enclosure to withstand pressure' and the long time of gas distribution ‘Test for non-transmission of an internal ignition' in 1.6m flameproof test slot,this thesis had analyzed the principle and process characteristics of the existing gas distribution system on flameproof test,and proposes the overall design goal of the gas distribution system.Through the analysis of the flow distribution method of the existing gas distribution system on flameproof test,the gas distribution technology will be further improved.Combining the gas distribution method with the flow distribution method,and using expert's professional knowledge and incremental PID control algorithm,then the design of explosion-proof test gas distribution system based on expert PID was completed.Based on the overall design of the system,the hardware and software modules are planned according to the function of the gas distribution system.And the hardware and software has been designed according to the functional characteristics of the module.The hardware part includes upper computer monitoring unit,lower computer control unit and gas distribution execution unit.The software is based on the joint design and development of the lower level STEP7 programming software and upper computer LabVIEW software.It adopts the idea of modular programming,so the operations of gas distribution control,three-element gas flow control,gas compressor,cold dryer and vacuum pump start&stop control,PID control algorithm,data acquisition,and data recording had been completed.In order to verify the efficiency,stability,and other performance indicators of gas distribution system,the verification test of the gas distribution system had been performed in an explosion-proof test slot whose diameter is 1.6 m(hereinafter abbreviated as: test slot).The experimental results show that the flow distribution method based on expert PID proposed in this thesis can effectively improve the accuracy and the stability of gas distribution system of the “Tests of ability of the enclosure to withstand pressure”.The gas distribution technology based on the combination of the flow distribution method and the partial pressure distribution method can effectively save the time of gas distribution of the “Test for non-transmission of an internal ignition”.