On the other hand, DTT for remote breakers can be easier
to engineer if the zone devices have the DTT capability in the
first place. However, we should notice that when issuing a
BFT, the Zone 1 IED needs to reach all remote breakers,
including remote breakers in Zone 2, and vice versa. As a
result, the built-in DTT signaling needs to be cross-wired
between the two ZPRs.