ABSTRACT
Pilot protection used for lines provides the possibilities of high-speed simul-
taneous detection of phase-and ground-fault protection for 100% of the
protected section from all terminals: the ideal primary protection goal. It is
a type of differential protection for which the quantities at the terminals are
compared by a communication channel, rather than by a direct-wire intercon-
nection of the relay input devices. The latter is impractical because of the
distances between the several terminals. Similar to differential schemes, pilot
schemes provide primary zone protection and no backup. Thus, they do not
require coordination with the protection in the adjacent system unless add-
itional backup is included as a part of the pilot scheme.
