Research On New Switch Control Circuit And Its Reliability And Safety Analysis

Switch control circuit is used to control the turnout.Its reliability and safety have a greatimpact on the efficiency and safety of train operation. Currently in our country, the switchcontrol circuit can be divided into three types according to switch machine: the first one isthe four-wire circuit to control DC switch machine; the second one is six-wire circuit appliedto control DC switch machine; the last one is the five-wire circuit for3-phase AC switchmachines. After been used for a long time, All this three types of switch control circuit havequestions as following: firstly, indication of switch position is determined only by means ofthe polarity of the diode, which is a bit simple.Therefore, under certain conditions, the outsidecircuit can form the diode characteristics resulting to a "false" indication of switch position,affecting the security of train operation; Secondly, these three turnout control circuits do nothave a matching lightning protection, so the whole system always gets fault caused bylightning strikes; Last, these control circuits belong to the relay interlocking system whichmakes switch control circuit frequently fail because of its complicating match wiring andrelays of low reliability due to their making process、materiel and other reasons. Questionsabove greatly affects the reliability of switch control circuit, but the switch control circuit isrequired to have the the highest technical requirements and the strongest fault protection inthe field of railway signal control. In this background, this paper begins the research for newturnout control circuit-the fully electronic switch circuit.This paper completes works as followings: Papers analyses failure modes and reasons offive-wire control circuit, summarizes its existing problems, and comprehensively uses FMEAand fault tree analysis method to do quantitative analysis of its performance on above basics.Papers describes the composition and work principle of the control system of SiemensSiwes2, and puts forward a solution to problems of five-wire control switch circuit on thebasic of its characteristics. On the foundation of the full analysis of the functionalrequirements and performance requirements of switch electronic circuit, fully electronicswitch circuit is designed which uses the high reliability components as power electronicswitches instead of electrical relays and multiple failure to safety measures. This paper usesthe Markov model to calculate the reliability of switch electronic circuit according to Thecomponent failure rate and other basic data;on the other hand, hardware failure probabilityassessment method is applied to determine security quantitate of switch electronic circuit.Finally, according to the "Railway Signal electromagnetic compatibility testing of electricalequipment and its limits",it does the static electricity test, electricity fast pulse test on inputand output lines and lightning protection test on switch electronic circuit results. The result shows that the electromagnetic compatibility of switch electronic circuit can achieve therequired level.Fully electronic switch circuit integrates technologies as power electronics technology,communication technology, computer technology and other technologies.It has advantagesalike small footprint, no maintenance or less maintenance, automatic protection andautomatic alarm when circuit is short. The fully electronic switch circuit is being of highreliability and safety, and it can improve the efficiency of train operation, and better ensuresafety. The fully electronic switch circuit is able to meet future demands for signal system ofChina’s railway.