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→13.3.2 Life Testing
===13.3.2 Life Testing===
Electrical life is defined as the number of operations under a defined load (make under load current, current carrying, breaking the load current). The total sequence of this switching cycle leads for the specific design parameters of a relay (bounce characteristics, materials, etc.) to the phenomena responsible for the later device failure, such as increased contact resistance, material transfer, arc erosion, and contact welding, for example ''<xr id="fig:Relation between the breaking currents of relays and electrical life requirements of switching systems"/> (Fig. 13.6)''.
As experience shows, failures during load switching are usually related to deterioration of the contact parts. Therefore the mechanical life must always be higher than the electrical life under the required load conditions. Typically the mechanical life is about 10 times higher than the electrical one.
