GE Multilin L30 Line Current Differential System 5-1455 SETTINGS 5.5 FLEXLOGIC5Figure 5–57: FLEXLOGIC EQUATION FOR VIRTUAL OUTPUT 47. Now write the complete FlexLogic expression required to implement the logic, making an effort to assemble the equa-tion in an order where Virtual Outputs that will be used as inputs to operators are created before needed. In caseswhere a lot of processing is required to perform logic, this may be difficult to achieve, but in most cases will not causeproblems as all logic is calculated at least four times per power frequency cycle. The possibility of a problem caused bysequential processing emphasizes the necessity to test the performance of FlexLogic before it is placed in service.In the following equation, virtual output 3 is used as an input to both latch 1 and timer 1 as arranged in the order shownbelow:DIG ELEM 2 OPCont Ip H1c OnNOTAND(2)= Virt Op 3Virt Op 4 OnVirt Op 1 OnVirt Op 2 OnVirt Ip 1 OnDIG ELEM 1 PKPXOR(2)Virt Op 3 OnOR(4)LATCH (S,R)Virt Op 3 OnTIMER 1Cont Ip H1c OnOR(3)TIMER 2= Virt Op 4ENDIn the expression above, the virtual output 4 input to the four-input OR is listed before it is created. This is typical of aform of feedback, in this case, used to create a seal-in effect with the latch, and is correct.FLEXLOGIC ENTRY n:Virt Op 3 OnFLEXLOGIC ENTRY n:OR (4)FLEXLOGIC ENTRY n:LATCH (S,R)919293FLEXLOGIC ENTRY n:DIG ELEM 1 PKPFLEXLOGIC ENTRY n:XOR8990XORFLEXLOGIC ENTRY n:Virt Op 1 OnFLEXLOGIC ENTRY n:Virt Op 2 OnFLEXLOGIC ENTRY n:Virt Ip 1 On868788FLEXLOGIC ENTRY n:Virt Op 4 On85FLEXLOGIC ENTRY n:=Virt Op 499FLEXLOGIC ENTRY n:OR (3)FLEXLOGIC ENTRY n:TIMER 2969798FLEXLOGIC ENTRY n:Virt Op 3 OnFLEXLOGIC ENTRY n:TIMER 19495LATCHResetSetORORT1T2 VIRTUALOUTPUT 4827031A2.VSDFLEXLOGIC ENTRY n:Cont Ip H1c On
