In applications where safety is of relevance the decisive issue is the availability of systems. While the contact life and the resistance to welding-up used to be in the foreground, it is now more and more the behaviour with small switching loads. So far the response contacts were primarily used for monitoring purposes. Today one relies additionally on the "load circuits" which have to professional switch less and less load in many applications.
Elesta takes the changed requirements into account with its notched-crown contact. The non-symmetrical contact system developed by this Swiss producer consists of a single contact (fixed contact) and a modified crown contact whose ring-shaped crown is divided into segments. The result is a ring featuring wedge-shaped protrusions, or "notches" between them.

From a physical contact point-of-view, two effects are taken advantage of: On the one hand the rising of the contact points leads to a higher contacting safety. On the other, the blade-like protrusions between the notches result in a very high surface pressure. A further advantage is that, unlike with bifurcated contacts, the contact spring isn't split at the expense of the force acting on the point of contact.

According to theory the switching reliability is increased nearly tenfold by twin contacts. Next to the reliability, however, it is also the economic efficiency which speaks for this contact system, particularly in long-term applications. Seeing that no additional coatings with precious metal are required, the notched crown is entirely self-financing for the user.