Fig. 13 illustrates an application where each relay takes
care of BF protection for all short-circuit trips that it initiates.
There are no external BFI signals exposed to spurious
initiation. In this configuration, when a relay is isolated for
testing, there are no BFI signals to be concerned with from the
human error point of view. When an individual relay is out of
service or has failed, there is no loss of BF protection.