GE L60 Instruction Manual

Also see for L60: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

5-194 L60 Line Phase Comparison Relay GE Multilin5.6 CONTROL ELEMENTS 5 SETTINGS5AR PAUSE:The pause input offers the possibility of freezing the autoreclose cycle until the pause signal disappears. This may be donewhen 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’ signaldisappears the autoreclose cycle is resumed by initiating AR 3-P DEAD TIME 2.This feature can be also used when a transformer is tapped from the protected line and a reclose is not desirable until thetransformer is removed from the line. In this case, the reclose scheme is ‘paused’ until the transformer is disconnected. TheAR PAUSE input will force a three-pole trip through the 3-P DEADTIME 2 path.EVOLVING FAULTS:1.25 cycles after the single pole dead time has been initiated, the AR FORCE 3P TRIP operand is set and it will be reset onlywhen the scheme is reset or goes to Lockout. This will ensure that when a fault on one phase evolves to include anotherphase 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-PoleTime Delay 2 for the second reclosure, and assume a permanent fault on the line. Also assume the scheme is in theReset state. For the first single-phase fault the AR 1-P DEAD TIME timer will be started, while for the first multi-phase faultthe AR 3-P DEAD TIME 1 timer will be started. If the AR 3P TD INIT signal is high, the AR 3-P DEAD TIME 2 will be started forthe first shot.If AR MAX NO OF SHOTS is set to “1”, upon the first reclose the shot counter is set to 1. Upon reclosing, the fault is againdetected by protection and reclose is initiated. The breaker is tripped three-pole through the AR SHOT COUNT >0 oper-and that will set the AR FORCE 3P operand. Because the shot counter has reached the maximum number of shots per-mitted the scheme is sent to the Lockout state.If AR MAX NO OF SHOTS is set to “2”, upon the first reclose the shot counter is set to 1. Upon reclosing, the fault is againdetected by protection and reclose is initiated. The breaker is tripped three-pole through the AR SHOT COUNT >0 oper-and that will set the AR FORCE 3P operand. After the second reclose the shot counter is set to 2. Upon reclosing, thefault is again detected by protection, the breaker is tripped three-pole, and reclose is initiated again. Because the shotcounter 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 reclosuresequence is successful (there is no initiating signal and the breaker is closed) the reset timer will time out returning thescheme 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 applicationsexcept for the following description, which assumes AR BKR SEQUENCE 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 Breaker1. The Close Breaker 1 signal will initiate the Transfer Timer. After the reclose of the first breaker the fault is againdetected by the protection, the breaker is tripped three pole and the autoreclose scheme is initiated. The Initiate signalwill stop the transfer timer. After the 3-P dead time times out the Close Breaker 1 signal will close first breaker againand will start the transfer timer. Since the fault is permanent the protection will trip again initiating the autoreclosescheme that will be 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 is started. The closeBreaker 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 aretwo options. If the AR BKR 1(2) FAIL OPTION is set to “Lockout”, the scheme will go to lockout state. If the AR BKR 1(2) FAILOPTION is set to “Continue”, the reclose process will continue with Breaker 2. At the same time the shot counter will bedecreased (since the closing process was not completed).