Guided by empirically developed arc-limiting graphs, typical switching processes can be distinguished. As <xr id="fig:Arc_limiting_graphs"/><!--Fig. 6.1--> illustrates, voltage and current determine if switching occurs without arcing, if it results in a glow discharge, short instable arcs are generated, or a fully developed electrical arc is created. The more exact current-voltage curve characte-ristics are depending on the electrical contact material used. They also depend on the contact gap and the atmosphere the switching occurs in; an ambient air atmosphere is assumed in the shown schematic example.

<figure id="fig:Arc_limiting_graphs">

</figure>

For the different requirements on the electrical contacts in various applications, it is useful to differentiate across the broad spectrum of possible load conditions guided by the arc-limiting graphs between four different partial ranges which result in typical physical effects:

The main characteristic of this load range is the presence of stable electrical arcs. Caused by the interaction between contact material and electrical arcs, the electrical life of contacts is limited by arc erosion or material transfer and in the case of higher make currents also by weld failures. For contact material selection the type of electrical load, i.e. resistive, inductive, capacitive, motor load, which determine the time function of the electrical current, is most critical.

<figure id="fig:Application ranges switching current and voltage">

information technology and transitioning into the power switching devices]]

</figure>