GE C60 Instruction Manual page 445

CHAPTER 5: SETTINGS
Autoreclose pause
The pause input offers the possibility of freezing the autoreclose cycle until the pause signal disappears. This can 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 freezes all four dead timers. When the 'pause'
signal disappears the autoreclose cycle is resumed by continuing the shot timer it was left at when paused.
This feature can be also used when a transformer is tapped from the protected line and a reclose is not wanted until the
transformer is removed from the line. In this case, the reclose scheme is "paused" until the transformer is disconnected.
The input forces a three-pole trip through the
AR PAUSE
Evolving faults
1.25 cycles after the single pole dead time has been initiated, the
the scheme is reset or goes to Lockout. This approach ensures that when a fault on one phase evolves to include another
phase during the single pole dead time of the auto-recloser the scheme forces a three-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 is started. If the
AR 3-P DEAD TIME 1
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
that sets the
AR FORCE 3P
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
that sets the
AR FORCE 3P
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 times out, returning the
scheme to the reset state with the shot counter set to "0" and 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
signal output from the dead time timers passes through the breaker selection logic to initiate reclosing of Breaker 1.
The Close Breaker 1 signal initiates 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 then
stops the transfer timer. After the 3-P dead time times out, the Close Breaker 1 signal closes the first breaker again
and starts the transfer timer. Since the fault is permanent, the protection trips again initiating the autoreclose scheme
that is sent to Lockout by the SHOT COUNT = MAX signal.
• Transient Fault — When the first reclose output signal is sent to close Breaker 1, the reset timer starts. The close
Breaker 1 signal initiates the transfer timer that times out and sends the close signal to the second breaker. If the
reclosure sequence is successful (both breakers closed and there is no initiating signal), the reset timer times out,
returning the scheme to the reset state with the shot counter set to 0. The scheme is ready for a new reclose cycle.
AR BKR1(2) reclose 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
the reclose process continues with Breaker 2. At the same time the shot counter is decreased (since the closing process
was not completed).
C60 BREAKER PROTECTION SYSTEM – INSTRUCTION MANUAL
3-P DEADTIME 2
AR 1-P DEAD TIME
AR 3P TD INIT
operand. Because the shot counter has reached the maximum number of shots permitted,
operand. After the second reclose, the shot counter is set to 2. Upon reclosing, the fault is
AR BKR SEQUENCE
is set to "Lockout," the scheme goes to lockout state. When it is set to "Continue,"
path.
operand is set and later resets only when
AR FORCE 3P TRIP
timer is started, while for the first multi-phase fault
signal is high, the
AR 3-P DEAD TIME 2
is "1-2" (reclose Breaker 1 before Breaker 2). The
CONTROL ELEMENTS
starts for the first shot.
operand
AR SHOT COUNT >0
operand
AR SHOT COUNT >0
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