| In resent years,the accidents on road transport of dangerous chemicals(RTDC)were on the rise,and the consequences were very serious.In order to reduce the property losses and improve the safety of the transportation,it is urgent to develop the safety monitoring system for the road transport of dangerous chemicals. The system can monitor the status of vehicles and chemicals.When the accident happens,the monitoring system can send the alarm information to the safety centre.Based on the new international function safety standard IEC 61508,this thesis assesses the risk of RTDC and establishes the simulation monitoring system with SIEMETIC S7-300F PLC module.First,the thesis introduces the concept of function safety and the profile of domestic and international RTDC.Aimed at the situation of RTDC in China,expound the necessity to monitor the RTDC.Second,briefed describe the principles of risk analysis and risk analysis methods in IEC 61508,compare the three methods of risk assessment which are recommended by the standard,the qualitative methods for risk assessment are performed to assess the risk of RTDC.Third,design and complete the RTDC monitoring system with the Siemens S7-300F PLC hardware module which meet the concept of function safety and fulfill the requirement of IEC 61508 standard.To test the state monitoring function and alarm functions of the PLC system,the limited program language-FBD is used to program the test software of PLC in the STEP 7 PLC program environment.At last,the PC configuration software WinCC is used to configure PC monitor screen.Through the MPI communications between PC and PLC,the monitoring informations are displayed on the screen,monitoring data and alarm data are recorded in the host computer.In accordance with the requirements of IEC 61508,the hardware failure rate was estimated by calculating.The safety functions of the system fulfill the requirements of SIL,so the design objectives are achieved. |
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