x/EN AP/Na7
-36 MiCOM P74
A zone is defined from a CT to an other CT or an open electrical element (coupler CB or
isolator).
When 2 CTs are used in the coupling and the coupler CB is closed, a virtual zone is created
from each bar feeder CT to the linked coupler CT.
The zone between the 2 coupler CTs belongs to that virtual zone which is behaving as the
overlap of the 2 connected zones.
There is one zone for BB1 to CT3, one zone for BB2 to CT4 and one virtual zone from CT3
to CT4.
P0879ENa
CT 3&4 not taken into account
Coupling Open
Isolator Closed
Isolator Closed
Zone 1 = CT1
Zone 2 = CT2
Zone 1 = BB1
Zone 2 = BB2
CB Closed
CB Closed
Check Zone = CT1 + CT2
FIGURE 19: BUS COUPLER OPEN
A zone is defined from a CT to an other CT or an open electrical element (coupler CB or
isolator).
When 2 CTs are used in the coupling and the coupler CB is open, the coupler CTs
measurements are not taken into account and the zones are extended is created from each
bar feeder CT to that open coupler CB.
There is one zone for BB1 and one zone for BB2.
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