Dynamic operation of magnetic reed relays

A model is developed for the dynamic operation of magnetic reed relays. From experimental data, it is found that the processes of dynamic magnetization and mechanical motion can be treated as separate and consecutive in time. Remarkable agreement was found between the experimentally determined static magnetic force and a force calculation based on an assumed domain structure inside the reed tips. The model basically assumes that the flux passes through the air gap in two areas near the tips of the reeds, each area equals half the cross-sectional area of the reed. The dynamic magnetization process is modeled with an improved version of Agarwal´s [7] model for eddy-current losses in laminations, and a differential equation for dynamic reed motion is derived. The very good agreement between theoretical and experimental results shows that this model gives a good representation of the dynamics of the system. Furthermore, the findings of the static force model based on domain concepts have basic application to the knowledge of magnetics in addition to the application here to reed relays.