A magnetic force in dry-reed relays

Analysis of an effective magnetic field in a contact gap of a heavy loaded reed

“…As a result, the blades may be twisted, so that both the contact force and mode of blade vibration during operation can be changed. The effect can be further increased at elevated temperatures due to the Joule heat generated at the real contact area [7]. Correct operation of the standard reeds is accomplished by applying a relatively high magnetic field (at least 50% overdriving is recommended) so that their blades usually are in saturation.…”

“…One is the use of an electronic theory of magnetism which first was employed by Portnoy [9] to analyze the regulation of a magnetomotive force (MMF) pull-in value of a reed relay. It seems to be a useful tool for our purposes [7], [10]- [12].…”

“…The field contributions due to the solenoids (with current), equivalent to the upper and lower blade, were calculated, and the components were summarized with respect to the orientation of the axes of the Cartesian coordinates [7], [12]. As a result, the total contribution of the blades , and is obtained in the form…”

“…However, the presence of the current's magnetic field is of great importance at any current, particularly during increased value at transient states (inrush current, closure according to AC-15 category of utilization, etc.). It affects the attractive force of the blades, causing the reed dynamics to vary and can, as a result, lead to its rapid damage [4]- [7]. In order for the reed to work under heavy loads, there is a need to know the spatial distortion with the contact current of the effective magnetic field in the reed gap.…”