Eaton EDR-5000 Nstallation, Operation And Maintenance Manual page 586

How does the Zone Coordination work (within the upstream protection device)?
When the zone coordination function is enabled, it works similar to a normal autoreclose function with the same setting
parameters: maximum reclosure attempts, dead timer for each shot, initiate functions for each shot, and other timers for
autoreclose process, but with the following zone coordination features to coordinate with the downstream reclosers.
The corresponding dead timer for each shot will be started even if the breaker of the upstream feeder relay is NOT
tripped from the assigned initiate protective functions.
The dead timer begins timing once the autoreclose senses a drawback of the assigned overcurrent protection
pickup signal. This exhibits that the fault current was tripped by the downstream recloser opening.
The shot counter of an enabled zone coordination will be incremented after the dead timer elapses, even there is no
breaker reclosing command issued. Meanwhile, the »
If a permanent fault exists after the downstream recloser is reclosed, the fault current makes the upstream
overcurrent protection pick up again, but with the pickup thresholds or operating curves controlled by the
incremented shot number. In this way, the upstream feeder will "follow" the protective settings of downstream
recloser shot by shot.
For a transient fault, the autoreclose with zone coordination will not be initiated again because of absence of the fault
current and will be reset normally after the expiration of the reset timer » t-Run2Ready« .
EDR-5000
-R 2R « timer is started.
T UN EADY
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