GE Multilin B30 Bus Differential System 5-1715 SETTINGS 5.7 CONTROL ELEMENTS5Consider the following configuration:The source 1 (SRC1) phase currents are CTs and phase voltages are bus VTs. The source 2 (SRC2) phase voltages areline VTs. Contact input 1 is set as the breaker 52a contact (optional).The conditions prior to flashover detection are:1. ΔVA is greater than pickup2. IA, IB, IC = 0; no current flows through the breaker3. 52a status = 0 (optional)The conditions at flashover detection are:1. ΔVA is less than pickup2. VAg, VBg, or VCg is lower than the pickup setting3. IA, IB, or IC is greater than the pickup current flowing through the breaker4. 52a status = 0 (optional)The element is operational only when phase-to-ground voltages are connected to relay terminals. The flashoverelement will not operate if delta voltages are applied.The breaker flashover settings are described below.• BRK 1 FLSHOVR SIDE 1 SRC: This setting specifies a signal source used to provide three-phase voltages and three-phase currents from one side of the current breaker. The source selected as a setting and must be configured withbreaker phase voltages and currents, even if only three (3) VTs are available across the breaker.• BRK 1 FLSHOVR SIDE 2 SRC: This setting specifies a signal source used to provide another set of three phase volt-ages whenever six (6) VTs are available across the breaker.• BRK 1 STATUS CLSD A to BRK 1 STATUS CLSD C: These settings specify FlexLogic operands to indicate the openstatus of the breaker. A separate FlexLogic operand can be selected to detect individual breaker pole status and pro-vide flashover detection. The recommended setting is 52a breaker contact or another operand defining the breakerpoles open status.• BRK 1 FLSHOVR V PKP: This setting specifies a pickup level for the phase voltages from both sides of the breaker. Ifsix VTs are available, opening the breaker leads to two possible combinations – live voltages from only one side of thebreaker, or live voltages from both sides of the breaker. Either case will set the scheme ready for flashover detectionupon detection of voltage above the selected value. Set BRK FLSHOVR V PKP to 85 to 90% of the nominal voltage.• BRK 1 FLSHOVR DIFF V PKP: This setting specifies a pickup level for the phase voltage difference when two VTs perphase are available across the breaker. The pickup voltage difference should be below the monitored voltage differ-ence when close or open breaker resistors are left in service. The setting is selected as primary volts differencebetween the sources.• BRK 1 FLSHOVR AMP PKP: This setting specifies the normal load current which can flow through the breaker.Depending on the flashover protection application, the flashover current can vary from levels of the charging currentwhen the line is de-energized (all line breakers open), to well above the maximum line (feeder) load (line/feeder con-nected to load).842745A1.CDRVTsVTsLine/FeederBreakerCTsBusNOTE
