5-66 B90 Low Impedance Bus Differential System GE Multilin5.3 SYSTEM SETUP 5 SETTINGS5For example, assume that B90 IED 4 is used for isolator monitoring while IEDs 1, 2, and 3 are used for protection. Conse-quently, the B90 FUNCTION setting of IED 4 must be set to “Logic” while B90 FUNCTION on the IEDs 1, 2 and 3 must be set to“Protection”. Normally open and closed auxiliary switches of a given isolator must be wired to the IED 4, and the Isolatorfeature must be enabled and configured appropriately.Assume the isolator shown below is monitored by the Isolator 1 feature. The ISOLATOR 1 POSITION is the FlexLogic™ oper-and asserted by the isolator 1 monitoring element. This operand must be configured to drive a direct output in order to sendthe connection status to IEDs 1, 2, and 3 where the bus replica is being utilized by differential protection. Assume bit 12 ofthe message originating at IED 4 is used for this purpose. This is achieved by applying the following settings:For IED 4: DIRECT OUTPUT DEVICE ID: “4” (this is the originating device)DIRECT OUT 12 OPERAND: “ISOLATOR 1 POSITION ” (this operand drives output number 12)The above information is to be received by IEDs 1, 2, and 3. Assume direct input 68 is to reflect the isolator position.For IEDs 1, 2, and 3: DIRECT INPUT 68 DEVICE: “4” (message received from IED 4)DIRECT INPUT 68 BIT NUMBER: “12” (using bit number 12)Once received, the isolator 1 status (known on IEDs 1, 2, and 3 as DIRECT INPUT 68 On ) is used for bus configuration:For IEDs 1, 2, and 3: BUS 1E CT: “F7” (the current wired to the F7 terminal)BUS 1E STATUS: “DIRECT INPUT 68 On”Figure 5–28: DIRECT INPUT AND OUTPUT SAMPLE CONFIGURATION FOR DYNAMIC BUS REPLICAIn the case of a breaker (or a tie-breaker), a breaker closed position with a dropout time of 40 to 60 ms is typically used asa connection status to avoid over-tripping or dead zones, depending on the relative position of the breaker and CT. Refer tothe chapter 9 for more details on configuring bus differential zones.836758A2 CDRZONE 2ZONE 1ISO 1normally open and closedauxiliary switchesISOLATOR 1 POSITIONsent as bit no.12 from IED no.4Received as DIRECTINPUT 68 Onphase A current, wired to F7phase B current, wired to F7phase C current, wired to F7BUS 1E CT = F7BUS 1E STATUS = DIRECT INPUT 68 OnIED 4IED 1IED 2IED 3
