Analysis Of Contact Failure Model Of Electromagnetic Relays Under Different Kinds Of Load Conditions

Electromagnetic relay is widely used in automatic control circuit in the field of aviation, electrical, defense, industrial, rail transportation equipment and weapons, its reliability has an important position which is difficult to replace by other electronic switching devices in automatic control circuit. If the electromagnetic relay fails, it will affect the reliable operation of the entire circuit and even industrial systems.The most susceptible to erosion damage of electromagnetic relay components are contacts, contact failure rate accounted for more than 80% of the total failure rate of the electromagnetic relay. In recent years, a large number of scholars and researchers have made a lot of experiments and detailed analysis of electromagnetic relay contacts for failure mode with resistive load. However, few researchers have conducted studies on electromagnetic relay contact failure modes with the conditions under inductive and capacitive loads, few literature comes out for compare analysis of the failure modes of the electromagnetic relay with resistive load, capacitive and inductive loads these three load conditions. Therefore, reliability tests under different load electromagnetic relay is designed, electromagnetic relay failure modes under different load conditions are analyzed, which places great significance for improving product design and manufacturing process technology, improving product reliability,ensuring the safe operation of the relay service.Embarked on the analysis of failure forms from the electromagnetic relay,electromagnetic relay contact failure characteristics is the focus of analysis, the electromagnetic relay performance metrics are determined as: bounce time, pull time,release time, overrun time and contact resistance. In this paper, electromagnetic relay contact reliability life test with different load is designed, 12 CHNT electromagnetic relays of JZX-22F(D) 2Z are selected as the research object of life test, throughmicrocontroller chip MC1413 and drivers, each relay is sequentially driven, and the electromagnetic relay performance metrics are test and record again in each 1000 contact actions. 4 object in each reliability test group of the resistive load, inductive load and capacitive load to give the trend over the degradation parameters.The deterioration of performance measurement indicators of different loads are determined by statistical analysis. Identifying failure modes under three different load electromagnetic relay as conclusions: overrun time under inductive load decreases, the main contacts fail to wear failure; under capacitive load conditions the contact gap is reduced, the contact resistance is reduced, the contact bridge failure is significant; contact resistance under conditions of resistive load increases, due to air oxidation or contamination produced by electrical erosion, the contact eventually fall to pollution failure.