Switching device
position/
position/
position/
position/
operation
operation
operation
operation
Bus sectionalizer
Disconnector
ON
ON
OFF
OFF
Interlocking lever
free
free
free
free
BZ1 earthing switch
OFF
OFF
OFF
OFF
Interlocking lever
blocked
blocked
free
free
BZ2 earthing switch
OFF
OFF
OFF
OFF
Interlocking lever
blocked
blocked
free
blocked
BZ1 disconnectors of
incomer / feeder panels
all OFF
ON
all OFF
all OFF
BZ2 disconnectors of
incomer / feeder panels
all OFF
all OFF
all OFF
ON
19
5.2.4.3 Bus sectionalizer
Usually an interlocking scheme
applying a mechanical (as per
5.2.3.1) and electromechanical inter-
locks using blocking coils (as per
5.2.2) is installed.
These blocking coils ensure safe
switchboard / bus sectionalizer ope-
ration if bus zones have to be sepa-
rated, reconnected or earthed.
They are mounted at drive
mechanism of:
•
Bus sectionalizer panel:
- busbar disconnector
- earthing switch bus zone 1
- earthing switch bus zone 2
•
Incomer and feeder panels:
- disconnector switch
a) Bus Zone Separation / Reconnection
BZ1
BZ2
BZ1
BZ2
BZ1
BZ2
BZ1
BZ2
blocking coil
Bus Zone 2 (BZ2)
Bus Zone 1 (BZ1)
Fig. 5.5
Principle of electromechanical interlocking bus
sectionalizer
^
^
BZ1 = Bus Zone 1
BZ2 = Bus Zone 2