Dead Break:

Open circuit condition, usually caused when actuating a switch slowly. Dead break results from low contact pressure, contact lift off or friction in the switch mechanism.

Contact bounce (Bounce):

The time during switching in which electrical instability (bounce) caused by the rebound of the contacts is observed. Relative mass of the contacts, forces and frequency of supporting members are all components that determine the extent of bounce. Total transfer time...

Detent:

A mechanism intended to hold actuator and contacts in a fixed position after the actuation force is removed or reduced to less than a specified value. Can also be referred to as tactile feel or feedback as it also identifies actuator position by means of tactile...
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