GE Multilin L90 Line Current Differential System 5-2315 SETTINGS 5.6 GROUPED ELEMENTS5c) 87L TRIPPATH: SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) SUPERVISING ELEMENTS 87L TRIPThe 87L trip element must be used to secure the generation of tripping outputs. It is especially recommended for use in allsingle-pole tripping applications. It provides the user with the capability of maintaining the trip signal while the fault currentis still flowing, to choose single-pole or three-pole tripping, to employ the received direct transfer trip (DTT) signals, and toassign supervising trip elements like the disturbance detector. The logic is used to ensure that the relay will:• Trip the faulted phase for a single line to ground fault, as detected by the line differential element.• Trip all three phases for any internal multiphase fault.• Trip all three phases for a second single line to ground fault during or following a single pole trip cycle.For maximum security, it is recommended the disturbance detector (plus other elements if required) be assigned to see achange in system status before a trip output is permitted. This ensures the relay will not issue a trip signal as a result ofincorrect settings, incorrect manipulations with a relay, or inter-relay communications problems (for example, extremelynoisy channels). The open pole detector provides forcing of three-pole tripping for sequential faults and close-onto-fault ifdesired. The open pole detector feature must be employed and adequately programmed for proper operation of this fea-ture. The 87L TRIP 1P OP and 87L TRIP 3P OP operands are provided to initiate single-pole or three-pole autoreclosing.If a direct transfer trip (DTT) is not required for the 87L trip scheme to operate, it should be disabled at the remoterelay via the GROUPED ELEMENTS SETTING GROUP 1(6) LINE DIFFERENTIAL ELEMENT CURRENT DIFFEREN-TIAL settings menu.• 87L TRIP FUNCTION: This setting is used to enable or disable the element.• 87L TRIP SOURCE: This setting is used to assign a source for seal-in function.• 87L TRIP MODE: This setting is used to select either three-pole or single-pole mode of operation.• 87L TRIP SUPV: This setting is used to assign a trip supervising element. The 50DD SV FlexLogic™ operand is recom-mended (the element has to be enabled); otherwise, elements like instantaneous overcurrent, distance, etc. can beused.• 87L TRIP FORCE 3-: This setting is used to select an element forcing three-pole tripping if any type fault occurswhen this element is active. Autoreclosure disabled can be utilized, or the autoreclosure counter if, for example, thesecond trip is required to be a three-pole signal. Likewise, any operand representing a change in the power systemconfiguration, can be applied. 87L TRIP87L TRIP FUNCTION:DisabledRange: Disabled, EnabledMESSAGE 87L TRIP SOURCE:SRC 1Range: SRC 1, SRC 2, SRC 3, SRC 4MESSAGE 87L TRIP MODE:3-PoleRange: 3-Pole, 1-PoleMESSAGE 87L TRIP SUPV:OffRange: FlexLogic™ operandMESSAGE 87L TRIP FORCE 3-:OffRange: FlexLogic™ operandMESSAGE 87L TRIP SEAL-IN:DisabledRange: Disabled, EnabledMESSAGE 87L TRIP SEAL-INPICKUP: 0.20 puRange: 0.20 to 0.80 pu in steps of 0.01MESSAGE 87L TRIP TARGET:Self-resetRange: Self-reset, Latched, DisabledMESSAGE 87L TRIP EVENTS:DisabledRange: Disabled, EnabledNOTE
