Experimental Study On Electric Life Of The Electromagnetic Relay With Double Contact Bridge

In recent years,with the wide application of high-power loads,the voltage and current levels switched by relays are becoming much higher than before.How to optimize the structure of the contact and improve the reliability of the relay has become a problem that the relay designers and manufacturers have to face.With the rapid development of communication technology,the power of communication base station is increasing rapidly,which puts higher requirements for the relay used in the matching power distribution unit.The relay with double contact bridge has four gaps when breaking current,which will reduce the arc erosion on each contact,to be easy to prevent the contact from failure.The factors affecting the electrical life and failure mechanism of the relay with double contact bridge have been paid much attention.In this paper,an experiment system based on model switch is developed.On this foundation,the action characteristics,degradation process of electrical performance parameters in life experiment and failure mechanism of relay are studied.Firstly,an experiment system based on model switch is designed and implemented.Through the designed model switch,the static pressure of the contact can be adjusted,and the contact spring system and magnetic blowing device can be replaced.The developed hardware test circuit realizes the real-time synchronous measurement of the electrical parameters of four contact bridges.The test software system based on Lab VIEW can realize the calculation,display and storage of the comprehensive electrical performance parameters such as arcing energy,bounce energy,breaking time and closing time.Secondly,the voltage and current waveforms of the double bridge under different static pressure combinations are compared,and the action characteristics of the relay in the switching load process are summarized.The influence of static pressure of contact and magnetic induction intensity of magnetic blowing system on the electrical characteristics of contact opening and closing process is analyzed.Then,the electrical life durability test is carried out under different static pressure combination and different magnetic induction strength of the contact bridge.The degradation process and variation regular pattern of the electric performance sensitive parameters such as arcing energy and bounce energy of each contact bridge are studied,and the influence of static pressure difference and magnetic field strength of the contact bridge on the electrical life of the relay is analyzed.Finally,the failure of the relay with double contact bridge is studied.Through the main changes of electrical performance sensitive parameters before the failure of the model switch,combined with the contact electron microscope topography and element analysis results,it is clear that the inconsistency of the double contact bridge is the fundamental cause of the relay failure.The results of the study can provide experimental means for the scientific evaluation and improvement of the relay with double contact bridge,and also has practical value for the structure optimization and life improvement of the relay with double contact bridge.