Influence of Characteristic Parameters on Contact Bounce in Reed Systems of Relays

The contact bounce of relays, which is the main cause of electric abrasion and material erosion, is inevitable. This paper presents an investigation of the parameters influencing the dynamics characteristics of contact bounce under different current loading. An experimental model system, which simulated the direct-driven reed systems of relays, was designed. The measurements of small bouncing displacement and dynamic contact force have been achieved separately by using a high-precision laser displacement sensor and a piezoelectric quartz sensor. Several results have been obtained: With driving force augmenting, the range of dynamic contact force variety, the maximum impact speed and over-travel of contacts increase, but the maximum bouncing displacement and time decrease, and the first coefficient of restitution tends to increase while the subsequent coefficients tend to decrease. With load current increasing, the over-travel of contacts increases, but the range of dynamic contact force variety and the maximum impact speed decrease, while the maximum bouncing displacement and time decrease at the first then increase. The coefficients of restitution have a decreasing tendency along with the current increasing. The experimental results would be helpful to the further study of the characteristic of contact bounce in DC electromagnetic relay.