Study On Arc Characteristics Of High-Power Small DC Relay

Urban Internet Data Center(IDC)adopts a hybrid power supply architecture to ensure its reliable operation.The core of this architecture is the High-power DC relay which can realize high-speed switching of dual power supplies.IDC requires that DC relays should have high-power,small-size,and high-speed switching operating characteristics,while traditional products are difficult to meet the above requirements at the same time.From a technical point of view,there is a contradiction between the rapid breaking of high-power arc and the requirement of small size.The fundamental solution to this contradiction is studying the arc-related characteristics of high-power DC relays.Therefore,it is necessary to design arc-extinguishing chamber of the DC relay and study its arcing characteristics.This paper focuses on the design and arc characteristics of the arc extinguishing chamber of the high-power DC relay with fast action capability.A simulation model of arc-extinguishing chamber of relay based on magnetohydrodynamics(MHD)was established,and the development of the arc between the contacts of the arc-extinguishing chamber were simulated.According to the simulation results,this paper compared and analyzed the arc motion state and the effect of arc voltage rising under different chamber structure parameters;obtained the influence of each parameter on the arc development,and pointed out The structure of the small-size chamber has an optimal match for the diffusion and cooling effects of the arc.Finally,the parameters of the relay chamber were given based on the simulation results and requirements,.Based on the parameters of the arc-extinguishing chamber given above,several relay prototypes were made.Firstly,the arc was simulated and analyzed during the switching under rated load.Secondly,an experimental circuit was build to test the switching ability of the relay prototypes under the rated power load;the arc images and related parameters were collected.Comparing the simulation and experimental results,it can be obtained that the prototypes can meet the fast switching ability under rated power load;this arc model can describe the arc shape evolution process and the arc voltage and current parameters during the actual switching.It indicated that the arc model has a good guiding significance for the design of high-power DC relay chamber.According to the arc simulation results,the distribution of current density in the arc extinguishing chamber,the reason of arc-root evolution process were explained;the change law of the maximum arc temperature value was analyzed.The relationship between the arcing time and different loads was explored of the relay.Lots of switching experiments were completed under the same power load(different load resistance)or the same resistance load(different breaking power).The statistical analysis of the experimental arcing time points out that the load power is not the only decisive factor in determining the arcing time;the coupling effect of the arc current and the external magnetic field also plays an important role.Based on simulation and experimental arcing time data,the functional relationship between arcing time,load resistance and load power level was given.This function reflect the actual arcing time in the switching of this type of relay.It is significant for the prediction of the arcing time of this type relay under actual working conditions.Finally,several relay prototypes were used to conduct electrical life experiments under rated power.The results of experiments showed that the relay can reach the requirement of 22,000 times of switching life under the rated high-power.The results of this paper are of certain significance in guiding the research and development of related fast switching DC high-power relays.