Main definitions

Learn more about selectivity: let's start with the ABC


There is selectivity between two circuit-breakers in series when, owing to an overcurrent flowing through both of them, the load-side circuit-breaker opens thereby protecting the circuit, whereas the one on the supply-side remains closed, thus guaranteeing power supply to the rest of the installation.

Total selectivity

Selectivity for any overcurrent value there may be in the installation.

Partial selectivity

Selectivity only up to a certain Is current value (ultimate selectivity value). If the current exceeds this value, selectivity between the two circuit-breakers is no longer guaranteed.

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