Pilot relaying is the best type for line protection. It is used whenever high-speed protection
is required for all types of short circuits and for any fault location. For two-terminal lines,
and for many multiterminal lines, all the terminal breakers are tripped practically
simultaneously, thereby permitting high-speed automatic reclosing. The combination of
high-speed tripping and high-speed reclosing permits the transmission system to be
loaded more nearly to its stability limit, thereby providing the maximum return on the
investment.