Physical and Chemical Analysis of Contact Points of relay on EMU

Abstract Electromagnetic relay is an essential part in electric control system on EMU. Because of frequent operation of on-off, external vibration, temperature rising and corrosive gas, etc when the EMU is in operation may cause wear and oxidation of the surface of contact points. Therefore, the electrical contact resistance increased, which cause contact electrical performance failure. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) was used to observe and measure the surface and section of contact points. The experimental result shows that the surface layer wear and contained phosphate and the section contained O, F, S, P, Ag, Ni elements. Thereafter the mechanism of efficacy losing of electromagnetic relay was discussed.