Ampere Turn (AT) Spec in Reed Switches

The Lower the Ampere Turn Spec the more sensitive the reed switch will be.

The numbers in the AT Spec represent the Pull-In range.

So if we were to look at two similar parts HE506-ND (AT rating 15-25) and part HE532-ND (AT Rating 30-35), and assuming we are using the same magnet the HE506-ND would be the first to sense the magnet as it approches and close. The HE532-ND would be less sensitive and would be the first to open as the magnet was pulled away from the switch.

See Also Switching Current vs Carry Current in a Reed Switch