GE Multilin C60 Breaker Protection System 5-2555 SETTINGS 5.8 INPUTS AND OUTPUTS5The FlexLogic operand response time to the contact input change is equal to the debounce time setting plus up to one pro-tection pass (variable and depending on system frequency if frequency tracking enabled). If the change of state occurs justafter a protection pass, the recognition is delayed until the subsequent protection pass; that is, by the entire duration of theprotection pass. If the change occurs just prior to a protection pass, the state is recognized immediately. Statistically a delayof half the protection pass is expected. Owing to the 0.5 ms scan rate, the time resolution for the input contact is below1msec.For example, 8 protection passes per cycle on a 60 Hz system correspond to a protection pass every 2.1 ms. With a con-tact debounce time setting of 3.0 ms, the FlexLogic operand-assert time limits are: 3.0 + 0.0 = 3.0 ms and 3.0 + 2.1 = 5.1ms. These time limits depend on how soon the protection pass runs after the debouncing time.Regardless of the contact debounce time setting, the contact input event is time-stamped with a 1 μs accuracy using thetime of the first scan corresponding to the new state (mark no. 2 below). Therefore, the time stamp reflects a change in theDC voltage across the contact input terminals that was not accidental as it was subsequently validated using the debouncetimer. Keep in mind that the associated FlexLogic operand is asserted/de-asserted later, after validating the change.The debounce algorithm is symmetrical: the same procedure and debounce time are used to filter the LOW-HIGH (marksno.1, 2, 3, and 4 in the figure below) and HIGH-LOW (marks no. 5, 6, 7, and 8 below) transitions.Figure 5–115: INPUT CONTACT DEBOUNCING MECHANISM AND TIME-STAMPING SAMPLE TIMINGContact inputs are isolated in groups of four to allow connection of wet contacts from different voltage sources for eachgroup. The CONTACT INPUT THRESHOLDS determine the minimum voltage required to detect a closed contact input. Thisvalue should be selected according to the following criteria: 17 for 24 V sources, 33 for 48 V sources, 84 for 110 to 125 Vsources and 166 for 250 V sources.For example, to use contact input H5a as a status input from the breaker 52b contact to seal-in the trip relay and record it inthe Event Records menu, make the following settings changes:CONTACT INPUT H5A ID: "Breaker Closed (52b)"CONTACT INPUT H5A EVENTS: "Enabled"Note that the 52b contact is closed when the breaker is open and open when the breaker is closed.842709A1.cdrDEBOUNCE TIME(user setting)At this time, thenew (HIGH)contact state isvalidatedThe FlexLogic TMoperand is going tobe asserted at thisprotection passThe FlexLogic TM operandchanges reflecting thevalidated contact stateTime stamp of the firstscan corresponding tothe new validated state islogged in the SOE record2 1 34 DEBOUNCE TIME(user setting)At this time, the new(LOW) contact state isvalidatedThe FlexLogic TMoperand is going to bede-asserted at thisprotection passThe FlexLogic TM operandchanges reflecting thevalidated contact state578Time stamp of the firstscan corresponding to thenew validated state islogged in the SOE record6SCAN TIME(0.5 msec)PROTECTION PASS(8 times a cycle controlled by thefrequency tracking mechanism)RAW CONTACTSTATEFLEXLOGICTMOPERANDINPUTVOLTAGEUSER-PROGRAMMABLE THRESHOLD
