Selectivity (circuit breakers)
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Selectivity, also known as circuit breaker discrimination, is the coordination of overcurrent protection devices so that a fault in the installation is cleared by the protection device located immediately upstream of the fault. The purpose of selectivity is to minimize the impact of a failure on the network. Faults in an installation are, for example, overload and short circuit.[1][2]
There are four ways in which selectivity is achieved:[3]
- Current selectivity: different breaking capacities
- Time selectivity: time delay before tripping of a breaker
- Energy based selectivity: analysis of the current waves
- Zone selective interlocking: communication between the breakers, forwarding a time delay instruction