The Design Of The Circuit Test Platform For DC Locomotive At Energized State

Contactor and relay are frequently-used parts in the diesel locomotive.And they are indispensable electric devices of the diesel locomotive since they have the features of simple,cost effective and convenient control.The contactor and relay can take control the diesel locomotive to start and brake normally,adjust the speed regulation and protect the circuit.Therefore,the performance of the contactor and relay has a direct influence on the locomotive working system and the safety of passenger.However,the existing methods of overhauling for the contactor and rely are limited.Currently,there is no devices that can be used to overhaul and test the contactor and relay on the diesel locomotive.To fill in the gap of the contactor and relay overhauling,we need to design a completely original testing device,which can be used to detect the performance of contactor and relay at the energized state in DC-Drive locomotive.This device is designed to work at the voltage of DC 110V,meanwhile,it can detect the instantaneous voltage and current when the electric component of locomotive is at attracting state.In this way,we can make sure whether the device under testing is at right state,and save the testing data for future reviewing.This paper is based on the principal analysis of all kind of the contactor and relay used on the diesel locomotive,and the standard of overhauling.Combining with practical situation,I design to build a measuring and controlling system and develop a micro test platform to overhaul the contactor and relay of the diesel locomotive,by using programmable logic controller(PLC)and a touch screen.The main contribution of the research is on the following aspects.1.Various contactors and relays of the diesel locomotive and current methods of overhauling are studied in detail.Then I put forward the objective and significance of devising the circuit test platform of DC locomotive at energized state.Meanwhile,I define the development direction of the test platform.2.According to the development purposes and design requirements,I design the whole structure of the circuit test platform of DC locomotive at energized state and explain the operating principle,which includes the composition of the overall test platform,detailed design of various hardware pieces and the drawing of all circuit.3.The measuring and controlling system of the circuit test platform of DC locomotive at energized state is designed,which includes the man-machine interface and writing the PLC Program or code with ladder diagram.4.Finally,I test the performance of the test platform,verify the reliability,then conclude the paper and put forward the future research.