Magnetic Saturation

Magnetic saturation exists when an increase of magnetization applied to a reed contact does not increase the magnetic flux through.

In the case of a magnet actuating a Reed Switch, it is the point at which a Reed Switch attains maximum closure force and moving the magnet any closer will not decrease static contact resistance any further. In the case of a Reed Switch being inside a coil, it is the overdrive beyond which the contact resistance does not drop any further.