5-202 L60 Line Phase Comparison Relay GE Multilin5.6 CONTROL ELEMENTS 5 SETTINGS5The detection of the breaker flashover is based on the following condition:1. Breaker open,2. Voltage drop measured from either side of the breaker during the flashover period,3. Voltage difference drop, and4. Measured flashover current through the breaker.Furthermore, the scheme is applicable for cases where either one or two sets of three-phase voltages are available acrossthe breaker.THREE VT BREAKER FLASHOVER APPLICATIONWhen only one set of VTs is available across the breaker, the BRK FLSHOVR SIDE 2 SRC setting should be “None”. To detectan open breaker condition in this application, the scheme checks if the per-phase voltages were recovered (picked up), thestatus of the breaker is open (contact input indicating the breaker status is off), and no flashover current is flowing. A con-tact showing the breaker status must be provided to the relay. The voltage difference will not be considered as a conditionfor open breaker in this part of the logic.Voltages must be present prior to flashover conditions. If the three VTs are placed after the breaker on theline (or feeder), and the downstream breaker is open, the measured voltage would be zero and the flash-over element will not be initiated.The flashover detection will reset if the current drops back to zero, the breaker closes, or the selected FlexLogic™ operandfor supervision changes to high. Using supervision through the BRK FLSHOVR SPV setting is recommended by selecting atrip operand that will not allow the flashover element to pickup prior to the trip.The flashover detection can be used for external alarm, re-tripping the breaker, or energizing the lockout relay.Consider the following configuration:The source 1 (SRC1) phase currents are feeder CTs and phase voltages are bus VTs, and Contact Input 1 is set as Breaker52a contact. The conditions prior to flashover detection are:1. 52a status = 02. VAg, VBg, or VCg is greater than the pickup setting3. IA, IB, IC = 0; no current flows through the breaker4. ΔVA is greater than pickup (not applicable in this scheme)MESSAGE BKR 1 FLSHOVR SPV B:OffRange: FlexLogic™ operandMESSAGE BKR 1 FLSHOVR SPV C:OffRange: FlexLogic™ operandMESSAGE BKR 1 FLSHOVR BLOCK:OffRange: FlexLogic™ operandMESSAGE BKR 1 FLSHOVRTARGET: Self-resetRange: Self-reset, Latched, DisabledMESSAGE BKR 1 FLSHOVREVENTS: DisabledRange: Disabled, EnabledNOTE842746A1.CDRBus VTsLine/FeederBreakerCTsBus
