Research On Arc And Welding Characteristics Of AC Magnetic Latching Relay

Contact is an important part of AC magnetic latching relay,and it is directly affects relay's electrical performance.The contact welding is the main factor that causes the failure of relay,and the occurrence of contact welding seriously restricts relay's electrical life.The welding of relay is affected by many factors,such as arc duration,arc energy,contact resistance,contact material and contact structure,etc.the coupling of these factors leads to the complex welding mechanism of relay contact.In order to solve this problem,the arc characteristics experiment and welding experiment of AC magnetic latching relay under resistance and resistance load are carried out by using the experiment platform of AC magnetic latching relayIn the arc characteristics experiment of AC magnetic latching relay,the breaking and making characteristics of relay arc are extracted by using the obtained arc current and voltage waveforms.The making characteristics include the making arc energy and the arc duration,and the breaking characteristics include the breaking arc energy,the arc duration and the arc image.By analyzing the similarities and differences of arc characteristics under the two load conditions,it is found that the making characteristics of relay are stably distributed in a small range,and the breaking current determines the breaking characteristics,which are random.The arcing duration of resistive load is similar to that of resistive-inductive load.The results show that the evolution of arc shape are similar under the two load conditions,and the arc brightness under the resistive-inductive load conditions is stronger.In the welding characteristics experiment of AC magnetic latching relay,the contact resistance,breaking characteristics and making characteristics of the contact are analyzed.The making characteristics of the relay include contact making bounce,making arc energy and arc duration.The breaking characteristics include breaking arc duration,arc energy and voltage.The analysis shows that the contact resistance of the relays always floats up and down around a fixed value.The making characteristics have an obvious law of change,showing a trend of first stabilizing and then increasing,and the breaking characteristic are random.The erosion of relay contact is worse under resistive load,and its electrical life is far less than that of resistive-inductive relay.Based on the change rules of relay contact characteristics,the condition and mechanism of welding are analyzed.It is found that the contact making bouncing is the main factor leading to the failure of welding of AC magnetic latching relay,and the welding of AC magnetic latching relay has accumulated effect and randomness.