Section 5 1MAC309294-MB FControl functions344 RER620Technical ManualIn general, loop control scheme is implemented in three different configurations. These aredefined by the number of reclosers in a loop and their respective types. They are fiverecloser, three recloser and four recloser configurations. The three- and five reclosersystems are basic arrangements; the four-recloser topology is a hybrid of the three- andfive-recloser topology.5.4.5.1 Three-Recloser Loop ControlThe three-recloser system bridges two sources with a normally open TiePoint recloser.Between each source and the TiePoint is a normally closed sectionalizing recloser. Thereare two fault scenarios to consider in the three-recloser system. In one scenario, a line faultoccurs between a source and its Sectionalizing recloser. The second scenario involves aline fault between the Sectionalizing and TiePoint recloserFigure 182: 3-Recloser Loop Control3-Recloser Fault 1 ScenarioIn a 3-recloser loop control scheme, Figure 182, if there is a permanent fault between theS1 circuit breaker and the sectionalizing recloser B at F1, the S1 circuit breaker willrecognize the fault and go through its reclosing shots to lockout (for illustration purposeswe will assume 3 operations to lockout for all devices). Recloser B will recognize a lossof voltage after the first circuit breaker operation, and if the voltage does not return togreater than live bus threshold value level for the livebus timer setting, it will automaticallytrip after t1 seconds, per Figure 183, isolating the faulted zone on the source side of therecloser. The tie-point recloser T at the same instant will recognize a loss of 3-phasevoltage on the S1 side of its recloser PTs. After a delay time of t2 seconds from the initialfault at S1 the tie-point recloser T will close. This establishes service from S2, recloser Aand through the tie-point recloser T to the faulted sectionalizing recloser B. Figure 183 andTable 313 summarize the events.S1S2
