GE D60 Instruction Manual

Also see for D60: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

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5-370 D60 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUALCONTROL ELEMENTS CHAPTER 5: SETTINGS5Coordinate the selected protection element (or elements in combination) with the selection of GND DIR O/C REV. For allforward external faults seen by an element set as GND DIR O/C FWD at one end of the line, the reverse-looking element setas GND DIR O/C REV at the other end picks up and provides a blocking signal. For greater security and to overcome spuriousdirectional element operation during transients, adding at least 0.5 cycles of pickup delay to the forward directionalelement is recommended.GND DIR O/C REV — This setting defines the FlexLogic operand (if any) of a protection element used in addition to zone 4 foridentifying reverse faults, and thus, for stopping the transmit signal and initiating the transient blocking timer.Good directional integrity is the key requirement for a reverse-looking protection element set as GND DIR O/C REV. Eventhough any FlexLogic operand can be set as GND DIR O/C REV, thereby enabling the user to combine responses of variousprotection elements or to apply extra conditions through FlexLogic equations, this extra signal is primarily meant to be theoutput operand from either the negative-sequence directional or neutral directional overcurrent element. As both theseelements have separate forward and reverse output operands, use the reverse indication (that is, NEG SEQ DIR OC1 REV orNEUTRAL DIR OC1 REV).Coordinate the selected protection element (or elements in combination) with the selection of GND DIR O/C FWD. For all theforward external faults seen by an element set as GND DIR O/C FWD at one end of the line, the reverse-looking element setas GND DIR O/C REV at the other end picks up and provides a blocking signal. For greater security and to overcome spuriousdirectional element operation during transients, adding a pickup delay greater than the pilot channel delay to the reversedirectional element is recommended.TRANS BLOCK PICKUP DELAY — This setting defines a transient blocking mechanism embedded in the directional comparisonunblocking scheme for coping with the exposure of both the over-reaching zone 2 and ground directional overcurrentfunction to current reversal conditions.The transient blocking logic applies to both operate (trip) and send (transmit) paths. Identifying the fault as a reverse faultprevents the scheme from both operating and keying the channel. If the reverse fault condition prevails for TRANS BLOCKPICKUP DELAY value, the blocking operation is extended by the transient blocking timer for the TRANS BLOCK RESET DELAYvalue. This allows riding through current reversal conditions.However, if distance zone 1 picks up during the transient blocking condition, the blocking action is removed. This is to copewith evolving faults when an external fault is followed by an internal fault. Without the zone 1 feedback, the trip is delayedunnecessarily.Do not set the TRANS BLOCK PICKUP DELAY longer than the fastest possible trip time for faults on an adjacent line so thatextended blocking action can be established. Take into account the pickup time of the reverse-looking elements of thescheme. To avoid locking up a spurious reverse fault indication that can occur during internal fault conditions, do not setthe delay defined by this setting too short.TRANS BLOCK RESET DELAY — This setting defines a transient blocking mechanism embedded in the directional comparisonunblocking scheme for coping with the exposure of the overreaching protection functions to current reversal conditions(see also the previous TRANS BLOCK PICKUP DELAY setting).Set this delay long enough to cope with transient conditions including not only current reversals but also spurious negativeand zero-sequence currents occurring during breaker operations (in the case when neutral directional or negative-sequence directional overcurrent functions are used). Consider the breaker failure time of the surrounding protectionsystems within the reach of the ground directional function used by the directional comparison unblocking scheme, tomake sure that the ground directional function is not jeopardized during delayed breaker operations.ECHO DURATION — This setting defines the guaranteed and exact duration of the echo pulse. The duration does not dependon the duration and shape of the received RX signals. This setting enables the relay to avoid a permanent lock-up of thetransmit/receive loop.ECHO LOCKOUT — This setting defines the lockout period for the echo logic after sending the echo pulse. This settingenables the relay to avoid oscillations of the echo pulses during an autoreclosure dead-time after clearing an internalfault.LINE END OPEN PICKUP DELAY — This setting defines the pickup value for validation of the line end open conditions asdetected by the line pickup logic via the LINE PICKUP LEO PKP FlexLogic operand. The validated line end open condition is arequirement for the directional comparison unblocking scheme to return a received echo signal (if the echo feature isenabled).When selecting this delay value, take into account the principle of operation and settings of the line pickup element, whichshould thus be enabled.