GE L90 Instruction Manual page 275

5 SETTINGS
AR PAUSE:
The 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 fre-
quency, 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
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
input will force a three-pole trip through the
AR PAUSE
EVOLVING FAULTS:
1.25 cycles after the single pole dead time has been initiated, the
when the scheme is reset or goes to Lockout. This will ensure that when a fault on one phase evolves to include another
phase during the single pole dead time of the auto-recloser the scheme will force a 3 pole trip and reclose.
RECLOSING SCHEME OPERATION FOR ONE BREAKER:
• Permanent Fault: Consider Mode 1, which calls for 1-Pole or 3-Pole Time Delay 1 for the first reclosure and 3-Pole
Time Delay 2 for the second reclosure, and assume a permanent fault on the line. Also assume the scheme is in the
Reset state. For the first single-phase fault the
the timer will be started. If the
AR 3-P DEAD TIME 1
the first shot.
If is set to "1", upon the first reclose the shot counter is set to 1. Upon reclosing, the fault is again
AR MAX NO OF SHOTS
detected by protection and reclose is initiated. The breaker is tripped three-pole through the
and that will set the
AR FORCE 3P
mitted the scheme is sent to the Lockout state.
If is set to "2", upon the first reclose the shot counter is set to 1. Upon reclosing, the fault is again
AR MAX NO OF SHOTS
detected by protection and reclose is initiated. The breaker is tripped three-pole through the
and that will set the
AR FORCE 3P
fault is again detected by protection, the breaker is tripped three-pole, and reclose is initiated again. Because the shot
counter has reached the maximum number of shots permitted the scheme is sent to the lockout state.
• Transient Fault: When a reclose output signal is sent to close the breaker the reset timer is started. If the reclosure
sequence is successful (there is no initiating signal and the breaker is closed) the reset timer will time out returning the
scheme to the reset state with the shot counter set to "0" making it ready for a new reclose cycle.
RECLOSING SCHEME OPERATION FOR TWO BREAKERS:
• Permanent Fault: The general method of operation is the same as that outlined for the one breaker applications
except for the following description, which assumes
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 3-P 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 initiating the autoreclose
scheme that will be sent to Lockout by the
• Transient Fault: When the first reclose output signal is sent to close Breaker 1, the reset timer is started. The close
Breaker 1 signal initiates the transfer timer that times out and sends the close signal to the second breaker. If the reclo-
sure sequence is successful (both breakers closed and there is no initiating signal) the reset timer will time out, return-
ing the scheme to the reset state with the shot counter set to 0. The scheme will be ready for a new reclose cycle.
AR BKR1(2) RECLS FAIL:
If the selected sequence is "1–2" or "2–1" and after the first or second reclose attempt the breaker fails to close, there are
two options. If the
AR BKR 1(2) FAIL OPTION
is set to "Continue", the reclose process will continue with Breaker 2. At the same time the shot counter will be
OPTION
decreased (since the closing process was not completed).
GE Multilin
AR 3-P DEAD TIME 2
3-P DEADTIME 2
AR FORCE 3P TRIP
AR 1-P DEAD TIME
AR 3P TD INIT
operand. Because the shot counter has reached the maximum number of shots per-
operand. After the second reclose the shot counter is set to 2. Upon reclosing, the
AR BKR SEQUENCE
SHOT COUNT = MAX
is set to "Lockout", the scheme will go to lockout state. If the
L90 Line Differential Relay
5.6 CONTROL ELEMENTS
.
path.
operand is set and it will be reset only
timer will be started, while for the first multi-phase fault
signal is high, the
AR 3-P DEAD TIME 2
AR SHOT COUNT >0
AR SHOT COUNT >0
is "1-2" (reclose Breaker 1 before Breaker 2)
signal.
will be started for
oper-
5
oper-
AR BKR 1(2) FAIL
5-185