GE L60 Instruction Manual

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

Contents

GE Multilin L60 Line Phase Comparison System 5-2835 SETTINGS 5.6 CONTROL ELEMENTS5BASIC RECLOSING OPERATION:Reclosing operation is determined primarily by the AR MODE and AR BKR SEQUENCE settings. The reclosing sequences arestarted by the initiate inputs. A reclose initiate signal sends the scheme into the reclose-in-progress (RIP) state, assertingthe AR RIP FlexLogic operand. The scheme is latched into the RIP state and resets only when an AR CLS BKR 1 (autore-close breaker 1) or AR CLS BKR 2 (autoreclose breaker 2) operand is generated or the scheme goes to the Lockout state.The dead time for the initial reclose operation is determined by either the AR 1-P DEAD TIME, AR 3-P DEAD TIME 1, or AR 3-PDEAD TIME 2 setting, depending on the fault type and the mode selected. After the dead time interval the scheme asserts theAR CLOSE BKR 1 or AR CLOSE BKR 2 operands, as determined by the sequence selected. These operands are latched untilthe breaker closes or the scheme goes to Reset or Lockout.There are three initiate programs: single pole initiate, three pole initiate and three pole, time delay initiate. Any of thesereclose initiate signals start the reclose cycle and set the reclose-in-progress ( AR RIP ) operand. The reclose-in-progressoperand is sealed-in until the Lockout or Reset signal appears.The three-pole initiate and three-pole time delay initiate signals are latched until the CLOSE BKR1 OR BKR2 or Lockout orReset signal appears.AR PAUSE:The pause input offers the possibility of freezing the autoreclose cycle until the pause signal disappears. This can 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 freezes all four dead timers. When the ‘pause’ signaldisappears 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 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 again