Eaton EDR-5000 Nstallation, Operation And Maintenance Manual page 569

Via the pre shot (fast trip), the AR-module is able to trip the breaker ahead
of the protection stage that has activated the AR-module. As a general rule,
a fast trip is either issued before the first reclosure attempt or after the last
permitted reclosure attempt.
1. At the beginning of the sequence, a "Pre shot" (Fast trip) is
executed before the time overcurrent protection element of any
device on the line completely times out. Purpose: to clear the fault
before any of the circuit protection trips or blows open. A short
time after the pre-shot occurs, the breaker can be re-closed into the
line and all circuits connected on the line will still be energized.
80%-90% of the faults are not permanent. After a period from 0.5 up
to 1 sec., the line is probably no longer faulty and the complete line
can be re-energized. If the line is still faulty, segments of the line
will be switched off selectively by the time over-current protection
module as a result of the system coordination.
2. A Pre shot (Fast trip) at the end of the reclosure sequence occurs
after the last permitted reclosure shot. Purpose: To prevent
unnecessary damage from the electrical equipment in case of
permanent faults. If the last reclosure attempt is executed and the
fault is still present, then the breaker can be tripped quickly before
the time overcurrent protection module has completely timed out.
EDR-5000
www.eaton.com
IM02602007E
569