340
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CONTROL ELEMENTS
CHAPTER 7: PROTECTION
Figure 280: Autoreclose scheme shot counter logic
Autoreclose pause input
The autoreclose pause input offers the possibility of freezing the autoreclose cycle until the
pause signal disappears. This may be done when a trip occurs and simultaneously or
previously, some conditions are detected such as out-of step or loss of guard frequency, or
a remote transfer trip signal is received. The pause signal blocks all three dead timers.
When the pause signal disappears, the autoreclose cycle is resumed by initiating the
AR 3-P
DEAD TIME 2
operand.
This feature can be also used when a transformer is tapped from the protected line and a
reclose is not desirable until the transformer is removed from the line. In this case, the
reclose scheme is paused until the transformer is disconnected. The
AR PAUSE
input will
force a three-pole trip through the
3-P Dead Time 2
path.
Figure 281: Autoreclose multi-shot supervision logic
Dual breaker operation
The general operation for two breaker reclosing on a permanent fault is the same as that
outlined for the single breaker application, except as follows, which assumes the
Breaker
Sequence
setting is “1-2” (reclose breaker 1 before breaker 2). The signal output from the
dead time timers passes through the breaker selection logic to initiate reclosing of breaker
1. The CLOSE BREAKER 1 signal will initiate the transfer timer. After the reclose of the first
breaker, the fault is again detected by the protection, the breaker is tripped three-pole and
the autoreclose scheme is initiated. The INITIATE signal will stop the transfer timer. After the
three-pole dead time times out, the CLOSE BREAKER 1 signal will close first breaker again
and will start the transfer timer. Since the fault is permanent, the protection will trip again
and initiate the autoreclose scheme that is sent to lockout by the SHOT COUNT = MAX
signal.
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