ABB REG316 4 Series Operating Instructions Manual page 325

REG 316*4 1MRB520049-Uen / Rev. F
Tripping delays t1 and t2
The tripping delay settings enable the BFP to be adapted to its
particular operating environment (e.g. circuit-breaker character-
istics etc.). Fig. 3.5.28.1 shows a typical timing diagram for
clearing a fault.
Fault
incidence (1) Start (2)
Tripping time
Fig. 3.5.28.1 Operation of the BFP/UT timers t1 and t2
Timing in the case of breaker failure:
(1) A fault has occurred and been detected by a protective de-
vice.
(2) A tripping command is transmitted to the circuit-breaker
after the unit protection operating time which also starts the
BFP. The tripping command can be either single (Start Lx)
or three-phase (Start L1L2L3). The redundant signals are
also activated at the same time.
(3) The circuit-breaker ruptures the fault current.
(4) After the reset delay t
BFP either detects that the fault current has been inter-
rupted and the protection function resets, or the fault cur-
rent continues to flow and a second attempt is made by the
BFP to trip the circuit-breaker.
(5) The second attempt to trip the circuit-breaker is successful
and the fault current is interrupted.
CB Repeat
open (3) trip (4)
t t + t
CB open Reset Margin
Delay t1
plus a safety margin t
Reset
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CB Backup
open (5) trip (6)
t t + t
CB open Reset Margin
Delay t2
, the
Margin
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