Siemens SENTRON - Selectivity with Three Identical Incoming Feeders; Fault Within the Protection Zone of the Downstream Protective Device

Selectivity with parallel incoming feeders
5.2 Selectivity with three identical incoming feeders
Selectivity for 3VA molded case circuit breakers
60 Configuration Manual, 08/2016, A5E03603181010-01
5.2 Selectivity with three identical incoming feeders
5.2.1 Fault within the protection zone of the downstream protective device
With three parallel-connected transformers, effective current selectivity can be achieved
because the characteristic displacement factor for the incoming feeder circuit breakers Q1,
Q2 and Q3 is within the range 2 < K
t-I
≤ 3.
① Characteristic displacement factor
② Total short-circuit current