8
Discriminating time
and reclaim time
¨
Definete tripping of the circuit breaker can be
carried out by a trip signal of the protection or
by the final trip function (6) of the auto-reclose
module. The final trip function (6) has to be
initiated by the start of the protection and allows
final CB tripping to be carried out in a shorter
time than the operate time of the protective
relay module. In this case the fault is most
probably of a permanent nature, and waiting for
the protection relay to trip might aggravate the
damage further. For the final trip function (6)
the desired trip time can be selected separately
for the initiation signals.
The purpose of the DEF.TRIP alarm is to give
an alarm when, after tripping of the CB, further
auto-reclosures are prevented.
A DEF TRIP alarm signals is given:
- when the final trip function (6) has operated
- when a protection relay module has tripped
(the circuit breaker was opened, an initiation
signal was active and no auto-reclosing was
started)
- if one of the initiation signals AR1...4 remains
active for more than two minutes
The alarm signal remains active until the fault
disappears. However, the duration of the alarm
signal is always at least 0.2 s. Four different
output signals are available: one for each initia-
tion signal. Thus it is possible to distinguish
between the alarms, for instance, those caused
by earth fault and those caused by short circuit.
Should several initiation signals be active at the
same time, only one alarm signal will be given
(the smallest in number). If, for example, AR2
and AR4 are active at the moment of tripping
the alarm signal is provided by "DEF.TRIP
AR2".
Should the circuit breaker position status input
CBPOS not be in use and final tripping is to be
carried out by the protection, special arrange-
ments are required. In this case the CBPOS
input is connected in parallel with the opening
coil of the circuit breaker (SGF2/7=1 and SGF2/
8=1). Then the auto-reclose module gets infor-
mation about the CB opening via the CBPOS
input and uses this information to generate a
DEF.TRIP alarm signal.
When the last shot or the final trip function (6),
has been carried out, the shot pointer indicates
the value LOCK-OUT (7), which means that
the auto-reclose module does not respond to any
initiation signal during the reclaim time. In
addition, the shot pointer indicates the value (7)
in the following situations:
- the circuit breaker operation failed
- the circuit breaker maintenance monitor is
zero (determined by the setting of SGF2/7)
- the circuit breaker is manually closed during
an auto-reclose sequence
- the circuit breaker is manually closed under
normal conditions (determined by the setting
of SGF1/6...7)
- the external input for inhibiting and inter-
rupting auto-reclosing (ARINH) is active
- the auto-reclose programme has been set out
of operation
When the signal or situation that resulted in
lock-out resets the reclaim time t
r
starts. When
the set reclaim time t
r
has elapsed the shot
pointer returns to the value (1).
When the circuit breaker is closed by the AR
shots 1...4, a discriminating time t
d
will be
started. Should one of the initiation signals
AR1...AR4 be activated during the discriminat-
ing time, the AR shot pointer moves to the value
(6). Then further AR shots are prevented and
definite tripping will follow. This function is
generally used at inverse time operation in order
to limit the number of auto-reclosures when
reclosing aggravates a fault situation further (the
operate time of the relay module shortens). The
discriminating time t
d
can be set out of use by
selecting the value 0.
The reclaim time is always started or restarted at
the circuit breaker close operation. A new initia-
tion signal during the reclaim time will perform
the next shot if selected. When all shots are
executed the auto-recloser is locked-out. When
the reclaim time has elapsed the lock-out situa-
tion is ended and the shot pointer return to its
original value (1).
Final trip function (6)
DEF.TRIP alarm
Lock-out
Содержание SPAA 341 C /E351
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