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→13.4.2.1 Electrical Life
The making and breaking currents for tests IEC/EN 60947-4-1 are shown in Table 13.2 for the different use categories
The electrical life of a motor switch is influenced primarily by arc erosion which is generated during make and break arcs on the contact surface. During AC-3 testing, for which the make current is six time the nominal rated current, the arc erosion is mainly caused by the make arcs, especially if frequent contact bounces >2 ms occur. Therefore the bounce characteristic of switching devices primarily used for “normal” use in switching on and off electrical motors is of critical importance. If make and break currents are the same, as in the ultilisation categories AC-1 and AC-4, the break erosion dominates the arc erosion so much that make erosion can be neglected.
<figtable id="tab:Important Use Categories and Their Typical Applications for Contactors
and Power Switches">
'''Table 13.1: Important Use Categories and Their Typical Applications for Contactorsand Power Switches'''
{| class="twocolortable" style="text-align: left; font-size: 12px"
|AC-1
|Non-inductive or slightly inductive loads, resistance furnaces
|-
|
|AC-2
|Slip ring motors: starting, switch-off
|}
</figtable>
