Influence of Interrupted Currents on Aging

Wear of fixed and moving contacts

Deterioration of contacts

Beyond the electrical-endurance limit, device temperature rise increases due to the greater contact resistance and a reduction in the pressure of contacts.

Wear of the arc chutes (insulating materials, separators)

Deterioration of insulation

Beyond the electrical-endurance limit, the insulation (input/output and between phases) is reduced, which results in a reduction of device suitability for isolation.

In this case, the safety of persons is not guaranteed.

I/In ≤ 0.4

This level of interrupted current corresponds to the mechanical durability (see Mechanical endurance).

I/In ≤ 0.8

This level of interrupted current corresponds to approximately 125 % of the electrical durability.

I/In

This level of interrupted current corresponds to the electrical durability at the specified voltage (see Electrical endurance).